PROCEEDINGS OF THE NATIONAL ASSOCIATION ADDRESSES DELIVERED AT THE CONVENTION OF THE NATIONAL SHELLFISHERIES ASSOCIATION Old Point Comfort, Virginia June 7-8-9, 1949, eK 2 RICK Driv victor Te_qhoosanofr, President James B, Engle, Secretary Dr, J,Nelson Gowanloch, Vice President, David H, Wallace, Treasurer, = Sa Le TABLE OF CONTENTS 1949 Addresses Ete What Can Science Offer the Oyster Grower, Dr, ThurlowsesiNetson Varying Characteristics of Oyster Bottoms, Aidan hy Soimers Variations in Intensity of Setting of Oysters in’ Long Island Sound, Dr, Victor b,, Loosanort Plans and Progress of Oyster Investigations in Florida, Robert MZ “ingle Invensity and Distribution of Oyster socusin Chesapeake Bay and Tributaries, Fred W, Sieling On the Culture of Oyster Larvae in the Laboratory, Harry C, Davis The Oyster Industry of North Carolina and Some of Its Problems, Dr A.W fo Chestnut Growth Observations of Oysters Held on Trays at Solomons Island, Md, G. Francis Beaven Fish and Wildlife Service Clam Investigations, John B, Glud The Spawning of Quahangs in Winter and Culture of Their Larvae in the Laboratory, ~ Dr, Victor L. Loosanorf and Harry C, Davis, Growth Studies in the Quahaugs, Venus mercenaria Dr, Harold H, Haskin Practical Problems of the Propagation of the Soft Shell Clam, Mya arenaria, Hasny Oeelurmer adi. A Study of Duck Farm Pollution of a Shellfish Area F; Dr. M, H, Bidwell and C, B, Kelly. Prelimimry Observations on the Predation of Commercial Shellfish by Conchs, Dr, Melbourne R, Carriker Toxic Effects of Oil Mixed with Carbonized Sand on Aquatic Animals, 14 20 28 33 39 43 ni 58 67 76 78 86 ( 93 Dr, Walter A, Chipman, Jr., & Dr. Paul S, Galtsoff, [ne nase a gtteasy PT ae) WAS Be a i eines Ot Ggee ice Wala, * re Opt pGS: yt ae 50 baS2..., 018 ae fer rig ye Met. CE Aaya pes iuLs pee. re : imag. HPO lG)! . «SC raph: awl ya Ieee a CL re CARS if bvelt ¢ cris! ah 3 Ps 5 Or) im ed ; ey. 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Professor of Zoology, Rutgers University, Biologist, New Jersey State Division of-Shellfisheries, In Charge, New Jersey Oyster Research Laboratory, INTRODUCTION As we gather here today on the shores of historic Chesapeake Bay to discuss the problems of the great shell-~ fish industry I am deeply conscious of the debt we owe to this area, It was here in Chesapeake Bay that the great biologist, the late Dr, William Keith Brooks of the Johns Hopkins University, undertook the first studies of the oyster in America, In 1878 he organized the Chesapeake Zoological Laboratory and during the following twenty- eight years during warm weather he was always at the seashore accompanied by a party of students, In keeping with the early traditions of the Johns Hopkins, the available money was mostly put into brains, not into buildings and boats, Starting with a vacant warehouse at Fort Wool* and three rowboats furnished by the Secre- tary of War, the group moved the next year into three barges of the Maryland Fish Commission at Crisfield, Maryland, In 1883 the laboratory was located in a build- ing leased from the Normal School in Hampton, Virginia, but a few moments drive from where we are now gathered, Thus we meet today in the very heart and home of oyster research in America, May we pause for a moment to pay tribute to this great scientist, As Chairman of the Maryland Oyster Commission Dr, Brooks submitted to the General Assembly of Maryland in 1884 a comprehensive re- port on "The Development and Protection of the Oyster in Maryland." If his recommendations had been followed there would be only one oyster problem for Chesapeake Bay today; where to find markets for the vast numbers of oysters pro- duced on the prolific reefs of this area, Of greater value to the country as a whole, however, has been the legacy Dr. Brooks left us in his students: Dr, James L, Kellogg long of Williams College Massachuset-~ ts whose work on molluscs has yet to be surpassed and whose student, David Belding, made such substantial con- tributions to the oyster, quahaug and scallop fisheries of Massachusetts, Dr, Caswell Grave for some years bio- logist of the Maryland Oyster Commission whose student, Dr, E, P. Churchill initiated the program of research on oyster larvae of the Fish and Wildlife Service, ‘tastly the even greater work and influence of my father, the late Dr, Julius Nelson at Rutgers, who lives on not only in your speaker but in William H, Dumont and in Jim Engle of the Fish and Wildlife Service, in Dr. C. A. Perry of the Maryland State Department of Health and Dr, C. Roy Elsey (-1-) BGsesel Sey veotwTodnl ot? £ 5 tse LY La —a fae — — * ' ns (vee weer Ald 0 J a Vi i : ‘ [ git erat 1s O's =) aw > SS is jvty sted aM a ies 4 f Sieg & be bet “ + é 5 si) 2 ah ft hy ay . ‘> Veer ‘ @ wn py ni a - aD . al : fl a ; y 5S iera j 2 4 : fl 2orees 31 favo ~ ¢. A (eaves gh sey pace Juats el). gS aepdiw yg i ie SOP LS v2 tmep% ats) Fecar v 797840 finelyieh ~ no WERIEMOS © ek Ay finstveal to +iditgy ak J erered: : 2 ba wEiesatosd tee Lean loved adt? no ip GS oF Ret icbléeimeaoowr sonahneds te asap A mah be oly coin ae Set! ict BH: foot “ag wif? 62 G08) sein RASS ght ez ay vial ie certekse te ee certainly wasn't dropped off an oyster boat! In Delaware Bay we have indirect evidence that in some seasons vast numbers of oyster larvae may be carri- ed upstream as much as fifteen miles from the planting grounds to set on the natural beds above, Where spawning sanctuaries have been set up we have repeatedly found much heavier sets up and down~ stream from the parent oysters, This would seem to support Prytherch's findings at Milford that larvae re- main close to their parents throughout the entire two weeks larval period, Another explanation, however, is possible, In 1921 I described and pictured 62 mature oyster larvae ready to set from the stomach of an adult oyster, Such larvae do not remain long in the digestive tract of the adult oyster, but are quickly carried out of the intestine, On emerging from their accidental prison they have frequently been seen to push out foot and velum and to swim away, Two years ago a group of large oysters were brought to Surf City, Barnegat Bay, from a distance of some eight miles, Less than two weeks later a heavy set approximately two weeks old was found on the oysters themselves and upon nearby gravel, There were no parent oysters in the area save a couple of bushels of small oysters in trays, The heavy set, confined to the shells of the large oysters and the gravel all within a few feet strongly suggests that ,there were larvae in the guts of the big oysters oysters liberated their load of captured young which promptly set in the immediate neighborhood. With hundreds of thousands cf oysters each pumping twenty, thirty or more quarts of water an hour vast numbers of oyster larvae must be captured and subsequently liber- ated, Absence of such capture by the adults may well be an important factor in the failure of-a depleted oyster bed to rehabilitate itself. It deserves much further study. Here is a field where radioactive tracer.elements can be used to great advantage, After twenty years experience on the Cape May shore of Delaware Bay we can give you the following as definite facts, During eighteen of these twenty years intensely heavy sets of oysters have occurred upon the flats within a few feet of our laboratory. Setting has taken place continuously night and day for from four to as much as ten weeks as determined from shells placed and removed each 24 hours, As high as 600 spat per concave surface of a quahaug shell have struck within a single 24-hour period, with over 100 ver shell each 2+ hour period for more than two weeks. Since the flats run bare each lo tide to a distance of 2500 feet, the larvae must be carried at least that distance with each flood tide, The only oysters seaward from our laboratory are on a small depleted natural bed -- the Drum Beds im the public quahaug area, We are forced to conclude there- fore, that the bulk of these larvae are produced on the (-i~) Liagd datete. ws tio beginners! 7 imaw pintedsen gt deat set f)on toes Pet 6. ey au aac citkatt at ake ou 34 4 Geo? $3 S2uG Seti Wee SHRIEse seme abet stat Ter rin eras 9 ee is Se. yo phew he Voln wad tseusem oe te gee ef ahawotg ee vi? peo sy «' y 9 “~' see8 iy te 2 saraget + “eetott “Ty MCh? Lins } era ¢ ie im= Tits ict DS a vee [ ever P (pO Oe oa "Is Jno Ly be gor greive “ait = s hats: tig Fi Lt ¢ ae The Rares 2t “3; fraatity hel Ptogasre owd page 2.4 “Slane trie egiewey “tens of ‘geofo ten’ et ped! gaol eer aee at itt rigor £ atosw Sure se preyols, Sar fetbooupe F £80k «« elcbeacd PUES aS PS 1LORer S- Oty beig Soe od. [hawt Svea soseyo ovisie4 Sh eo Wet. (edt toned ahvced Hae . Soane PUA itis) Vil tp. eh Ci Setege slut adr to Jost Pesashtota Time what: arty rane mq. ,eatvearnt 9:13 to Cae ls i aay ee ees A mm Vieaa/ pect are ets foc 1q . *4 ites 2. ode erase ous \, cinescin: 4 Gne-mtev dee “WRG. FE gS Gee er to en} — Jatioc? Grew emis o_sel ~ ut cue Ges ee sts Ghote T¢: gamelan « wott DL ensovree giuiiestaa yes Peo ‘vest Beesial aionw Vise Roe GMs GoTiomnS esereGo 5 i). Ge S063 env WVAE 4o%m at? gt gcelayo tnetay a7 v av ey Lavery doe to sonandh. ,fete ~ ~*~ tozatedh B to omwltat x ei “odor dnefiogmt na od deoe savienoh AI, Blostt wath Dtdadex ot bad sodeyo : sel iccol het aqertty hieFt « wk eel vcbess sedt wt ,s0aesrp Ssoty of Seu 6d ns> stnomele Te 0aT7 aed oft-no oocalthme ersoy ysnews dod OY oa! voy Svig née Sw Yat oxnweked ‘% stone ran “Siow? osérit 36 nootrgks yak .ciost ofintied 9 heVigese aval eretaxs 1 aon yvsed YLoamsint azaay ugrosbtodel avo to Jost wet « nhtyviv cialy edt cogs . i Ye leis —_ e Jaton ens per aonted batt a coe 7 - n 7 derines Ju 5 wlbav fet cq dots es 0) “Set mort uh tion Aneo ievamer baa booetig effeste 4 pump ae es | psi oN ARNIS ee Joga 00 Bs) ae hina hg By hog tum ae aan np 5 shinee vas mom scelt o otis =) ‘od tem ohee 200": BOE ‘ea . pel? Beal? de ire ip paris ae - pt ove prorat att ek md planted beds above us and are carried seaward during early development, By successively sinking on the ebb and rising on the flood they return to ow New Jersey shore, Due to the effects of the rotation of the earth they are carried tovard the Delaware shore during ebb tide while being borne toward the New Jersey side as the tide swings to the right with the flood. Outside the bar, situated some 3000 feet from the high water mark, and in 14 to 20 feet of water are hundreds of acres of oyster bottom which have been heavily shelled year after year. In the main these shells have caught fewer spat in an entire summer than attach to similar shells in one tide close to the shore, It is evident therefore that with each flood tide these larvae by countless bil- lions pass by these shells to attach to shells in shoal water on the flats, We have had excellent success moving such heavily set shells offshore in- to deeper water when the oldest are but 10 days of age, It is my opinion that no more important pro- blem faces the Chesapeake Bay area than to deter- mine the role of parent oysters in capturing their young and finding out how far the larvae ere carried, Here is a field in which radioactive’ tracer elements or even staining as used by Dr, Loosanoff could be employed to great advantage, It is understood that Dr, Chipman has recently completed the training required in handling radio~ active elements, May I urgently recommend the cine of oyster larvae for his early considera- ion, 2. Oyster enemies Much has been learned about the enemies of the oyster but so far scienee has yet to give us methods for the control of oyster enemies comparable to those developed for the eradication of insect pests, for example, Since boring snails are also molluscs, breathing through gills, they are so close to the oyster that it is very doubtful if any method of poisoning them can be found which will not harm the oysters or render them unfit for human food, The plan to kill oyster drills through corrosive sublimate, or bichloride of mercury, as recently proposed appears highly dangerous through the habit of the oyster loading up with heavy metals such as zinc, bismuth, lead, mercury or copper whenever these occur in appreciable quantities in the surrounding waters, The six year study of the oyster drill, Urosalpinx, carried on by Dr. L; "A. Stauber at our laboratory with the aid of W, P, A. and P.\/.A. (Se) y H, BORiuB baanaes eotiete oie ting mtr Ore e: bg te wheat Wie Se BARN HANES 3 is aire nae, ame oF © ess oy J yey nyt ou Be ih he sata sy Mis he | yet Shoe Si hi ta 74) hod sully - Geert Nera spat: SU Sra \od Seteice oR Ae, Men Oe byte 30 (Aries Bote Axle Lett Shes iiig- eel aoculs Fidei Bd) “os xoibae ii by “melons RhD -yweTSh aol a? Ogelt ots ten GOQE oe, Uae By ce a oie pore | ey ta. sG9% OS ot ir at Bis ie row dati wit? ba Site : gosta"; aha) ic Re ors ; ei “Thee «? re | é iva ‘ags} bo ery baer tea we ptdes a2 a. “ols oye tdgvao py Stigcte eenrkt Puy 2M af citede te biele cP cibedee ant? deere ; P ato nigih carbene At. 22 Oks sit oF e20f4 1, =bte Rie Wdu 3 na rev Aso ohh ‘Bodlt Nous sittv wie SEs = «: wee vot Gilet eted? vc oneg eal feetiste. qi attlecoe se7el> wilt he % ‘6 S 4 iD bade ae | , i Pate.) Y 4 al! Tara. 3 = > yy 2 wavy | | Cid Be =~ 7 , =r, ot “aan { : i ie t = nad ey * wa o cfaqnn Of 29" . : j ante | ot? conte 4 tear PeHy: ats mone Oot? of Siepltees ie =n ia’ ‘ Lea a ¥! 1 Zi ort fron - Jae «ug bial . Jor dL 2006, 90d) ,atit. ing iets pa teeta Ute no eters tq. baste ‘amis wore Blase oF col? eioge¢ aid nowhet ftiw sat 4 “22 wt? nt [otimes f29 tevrEO. 102 ego Sserd. Sm en! OE ol .fewec o to ato sD ‘a xo othe a. “eT ac? lo cotatgoatas evoteaun 33 2° ‘st%® Off al gablrow st sakeaare’ Bonk 4 ’ = ¢ e™ J i v me on tod Site tiv oata beawtel “ 4 ms vit mde’ au Tie? ity % ,anbfots) ait a ar - Ea o7Ts ayes Ta io rae ia 2oitnd ¢ of ‘a? CORE Ts s428¢ med oUF .at 5 é yb aeri eit Poon . ers wm) iy aan Saaremaa ge ngaed me. O30m Heerte a Peg daa - alee ow sa . ¥ ipwtae place among the states with a production of one seventh of the total oyster crop of the United States, With the onset of the depression new grounds were not taken up, three of the driest years of record plus a hurricane Look their heavy toll, with drills and the mud worm, Polydora, reducing the oyster crop by approxi~ mately one half, New Jersey slipped back into fifth place among the states, Return to our former position can only be accomplished through vigorous control of oyster pests; especially the drill. 3, Favorable growing and fattening grounds Here science has been of little help; the oyster grower has had to depend almost wholly upon his own experience and that of others, We do not yet lmow why oysters grow well on some grounds, poorly on ad- joining grounds. Even on the same ground, as every oyster grower well knows, growth and fattening may be good one year, poor the next, Much scientific work has been done in this field but as yet there is little that science can tell you of practical value, From our experience in New Jersey we know that when the diatom Skeletonema is abundant we have had fat oysters of excellent flavor, We have seen oysters increase in yield almost a pint per bushel in one week following a heavy invasion of this diatom, When associated with objectionable forms such as the "gremlin" Bicoeca in Great South Bay in 1943 oysters may remain thin and poor even in the presence of abundant Skeletonema, Our experience in New Jersey does not support the conclusion of Dr, Loosanoff and his coworkers that oysters in nature will not feed'in the presence of thick suspen- sions of food organisms, We have found oysters to feed actively throughout dense swarming of the dinoflagellate Amphidinium fusiforme, when the water had turned red and was a veritable soup of these algae and of their zobspores, Since Dr, Loosanoff's observations were made under laboratory conditions while ours were made in the open waters of Delaware Bay it is probable that poison- ous substances produced by the algae at Milforg were either not present in Delaware Bay or were quickly des- troyed in our open waters, I have to be shown before I will believe that oysters will starve and die in nature in the midst of abundant food, 4, Protection from industrial and domestic pollution Although in the past some oyster grovers have looked upon bacteriologists as their worst enemies, we must all agree that in the main sanitary standards have aided and protected the industry, It is encouraging to find the United States Public Health Service now engaged in active research looking toward new techniques for identifying objectionable bacteria and to sounder more reliable methods of determing the sanitary quality of shellfish. (7) a '& ia b ae, Cf ‘ “ — ‘ > } +) > _ , ° = a] w t i i } ; 4 j i Ml ( s j ' - > t ' 4 4°45) rit Bu L's , he . > oy = ne ss _ ah Pe 4 ¥ rift 7 La 7 a »©< a rs % he f - § b5fey pe iT We pf) s reac ? S rr r 7 ,aTa ¢ ta Ay — . ' : Yer { a) We . { ” Si \e . ar rem ft . : Ale - es - 2G »' 7 "TT Aeso 4)” Looe ap wots sm ~ [Se Bowe ad “0 7,4 = ' 7 : : aivl a - dey > 3 J 44 ee |! v) a. i - é I i a bo 5 Pie RIS me Seoit oer te yoe MIL thet +s eapb arog nas , Li EES Seat 0, r eget oe Fes 7 yea Se SANs Se st eee: ad G! giidet9-9u8’ ae oaptee w Ae beg 4 Vis + OW oo cat L [ PhS ders nl @¢cammitt Sicteyo rseoetat = “Pecl (aoe Be ‘Sthenigot weet ane at fores- nig: « Jawle heaby “a Taw ale tease aly Cote! , nornaval yvreed v . , ’ a0, ft 3 = & af 4aw - md ie i i « — es : uot ofdasriey S & in 6 Zonctoa! xt oonts- wroveqedog eens fw aqvlsiinos visosJetotal 4 j : E otews lad rq ated a - 6 aagle ort bp cathotm coonsiedia aap <6 “at etaweled nl tn }F fog tests © ‘tedt simbewde! a tat , oon fo x) Dre! mere a Do ate f Shiu Ms a g. 2 tee ones teks pe nt tr onath PB hel moa prt: Taeis. Se es sala: ts paved oka unde ¥°9020u Ho. ta dt. oat OBLVIAE slant Federal and state attack on aquatic pollution is being actively pushed in many quarters, industry is coopera- ting as never before, ready to spend money liberally for research on waste disposal. Noteworthy is the two million dollar project of the U, S, Public Health Service which will be launched July lst for the con- trol of stream pollution, Concrete evidence of improvement of the waters of New York Harbor. is seen in a group of oysters on exhibit in this room, The late Captain Will Elsworth told me in 1923 that he had caught his last oysters in the lower Hudson River in 1917 close to the Statue of Liberty. Exhibited here today is a group of ex~ cellent oysters dredged last December on Robbin's Reef within the very shadow of the Statue of Liberty, One is tempted to become sentimental, and to suggest that even the lowly oyster is enjoying the protection of our Goddess of Liberty, Finally we shall learn during this convention of the excellent progress made by Dr, Loosanoff and his associates in raisins oyster and quahaug larvae to setting size at the Milford Laboratory, Armed with such technique there is every reason to hope that through selective breeding we can obtain oysters and aquahaugs capable of attaining market size in half tha time now required, From the growth studies of Martin and ourselves in New Jersey and of Dr, Loosanoff at Milford we know that certain oysters in’ any lot will outgrow others by as much as ten to one, In my own studies of water pumpage by eysters it has been found that two year old Cape May oysters select- ed through rigorous competition in the heavy sets of that area, can out-pump eight year old Barnegat Bay oysters, grown from non-selected seed, by at least two to one, Since the oyster must obtain the mater- jals for growth and fattening from the water which it pumps, it follows that ability to pump water is probably the most important characteristic of a vigorous oyster, Unless the oyster is very dif- ferent from most other animals such vigor is inheri- ted in at least a portion of the offspring, Select- ion of the fastest growers in each succeeding genera- tion should soon give us an oyster comparable to the large Pacific oyster imported from Japan which has in eighteen months reached a size where eight of them will make a pint, This may sound fantastic but science has produced equally miraculous results with other domestic and game animals such as trout; why not with oysters? To accomplish our goal re- search positions in the shellfisheries field must be made sufficiently attractive in salary and in tenure to interest young men of ability and with adequate training, Above all they must have com- plete independence of, and protection from, politi- cal interference, Looking back over half a century it is clearly evident that bad politics has been a (-8-) - pare’ Ci ital phir Sksaupe ao. tontto-otets has fatebot . ‘et eer (iA. ghee tisk syne: met Aepclesaey, foe anid ; 22. Yene Uwe et Ykoay ,wtoted Yvert ee “ Cane cent Peseapald ateaw Ao. ceeeno » dae bist. ,& ett ta tooteni aefiok abi ; ts, athe ist Or yl tademel od Tilw Sain ontyrme : mitulifog mante to Lor i“ ee) ‘mit Le Jpitlortinnt Te wambates efe<9n0)D R 75t0 Wi. oon & et Shoe ot coc te slaol inf 2c 1S cleiqad ateliodt» e007 2b zl +idtitzs emer Git JAsivS Bel ef dats £°C¢L of on hlas > wate: qae - Hf Sevle mee ten mes ad? at ar a | eilini ovat (ezictxs - .vivedbt: to rol vi 4 fot retgu S simth esa3rvn tnosffeo s eke Veto +o. ar i? Gy Aedes Perv es mit de toon ; Oe Jarre ov a ier ah Pa aes 35 in ig 2? @L ond ——) ONTO lo # i: a0 aad e %) BP Wstac- cas mat oft! ove Fantd a ye - ; 270 «isu tie: ‘SY Steet aviseole: agoms saufs 7 ~ aalP a ptaiie.t ta te Sidayes enttetagn fie et te me fi SS awit) binary mot sat? «(3 7 “iste bald nt qorips ting Ey a2d etr-. saseto of} sesfnd ,cetevo avotogty O. SUS2¥ dove alanins gacie tcon mosk Jo078t epi 7s? ods to nobttod £2 jesel.da a? bse B gales ATs of aaawory Jasven? Sc) to. fo wfs or SP aidptigio IIAKO. me eu avd aes HIoote no aul Boge one mage. wart £02 sexe far worse enemy of the oyster than pollution, star~- fish, drills and all other 1.2tural enemies combined, You .Jny this industry have the political power to protect the scientists who are ready and eager to serve you; their fate is largely in your hands in a future that is bright with promise, (Se) eta sh, Ga uh log ley 2 BE? a YG a ¥! HL Ls, ius ey by, a? Varying Characteristics of Oyster Bottom = by= Allan A, Sollers, Commissioner Maryland Department of Tidewater Fisheries Annapolis, Md. 2 OK OK 2fs Kk OK An oyster, Mr, Chairman and friends, is the one thing in the world that I envy, The lazy rascal spends just about his entire life lying in bed, To complicate the matter further, this fastidious gentle- man is a bit particular about the kind of bed he lies in, If iteois..too,soft he,settles in and dies. If the bed is too hard and shifting he likewise is covered up and departs for the oyster spirit world, Hence we are compelled to take due notice of these eccentricities of our exacting bivalved associate; our personal eco~ nomic welfare is dependent on it, The uniniated, though otherwise well informed, might quickly ask, "Why haven't physical and chemical analyses been made of the submerged lands, the sever- al classes established, and these classes correlated with their capacity to grow oysters?" He would doubt- less substantiate his question by pointing out the work done by the agricultural experiment stations ashore and refer to the glib way that farmers speak of loams, clays and sandy soils, marls and the host of other classifications in that book, Such a classification might be useful; I have discussed the question with those qualified and have never discouraged such an attempt. JI have by the same reasoning never strongly advocated such an ef- fort for fear of oversimplification, There is more to the problem than would show in a simple physical analysis of the ground in question, I will discuss variations, complications and exceptions later, If an attempt were made to classify the sub- merged lands, the Chesapeake Bay would be a good place to make it; surely we have every combination in the world there, and maybe one over for good mea~ sure, Three general classifications would be immediate-~ ly apparent, The first to attract attention would be the sands along the shore lines, They feel relatively hard and firm to the bare feet of bathers but they lack any ad- hesive or cohesive qualities and shift about with the pounding of the surf, Their extent off shore is de- pendent on the degree to which the area in question is exposed to heavy seas, Second, just beyond the shifting sands, we again find sand, but something has been added, Mixed with the coarse grains of sand, are smaller particles that possess definite adhesive qualities, I am not sure C10) Ove “Ee pea soliogest emos As sis eal iiljalesive Io tap) t0% Jr0T ste >: i nl ~*e Gfuow suet sidow aie o vs ,tbideouy 2h bniozs 7 to aicvfena Ss AuGgisyuoxe hoa daokianllymoy samiiahtar ood ebet eyev dgametis na TT ; S aleeepaeto ty -tixal eae Yai Ow elegce yk eolem OF ooal ‘ro Bao sdyse hos .o 1: Ad Siiov end « oe $00¥ ake? You aoe ‘Span Ga? telca ayren 3 flew 3. , brio ae _ SE tii eee wives te od? ‘To pntonc > 7 t= Po Aa pot Ed aniag yatezg sity bax Sr on ak teed pmo oo : Mec: fi...) apr: 19 4%8 26 ¢. > # 26 r peie@ af}. 22 beret t1ot Yio’ bos SaalereM ; Bc Ges Velo edit eid? io atutainba oe Sor ito en of3 cai? tas‘ios dadwamoe aft notsveantd w Heels et puvdxls sil .taol zt roles ould _pebtesidnos sii ULI ROO Aaa ofies et bas + 90% afd To oflqe nt mossod te oi RYO jostfeoks o} caenk cia ad 52 tesqac bo TSO oo pisdathortt _ ie = poliesltivacio aloai2 o a9 saenow 5 bhsa! aT od to eland . : . ‘eros breagen! oF Totus ¥ 4 eulres a isis? % Gime ats |) § mek Stet a) Te5 >@¥ i TaatE 228 NOUBA =f Geateyo to Pe hedge A "het por. Olver & oR St Gunrseomib? 1 eased polbelo Ofint? deg a7 MS panei eT tie den axe Sais ; _ snatvecns cit falurinn> Hur ost —Ca0 wt goeties tq wi? fraiuet4t See exon i gent 1 Ste evasion tecers silf 14 a¢estaned ‘oS Vien Of Sbver B49 Mitel oat asiined bew0e oF eiisitows o¢ ESiw epmlrin iG mlisiwise wen a ine 4? GlEluqsoiet eke jot Oia yser cower ont tuwsety 7h gral 6 t galsere 7 HEC 20 Ne eee? GY al sok? eres ex Pact Sis} come te Enos. *zcfal eteer svlew 2845 off ata .contetiweven ,kcote =, fv fintcg Fan pew eeoc! argh ima hasoet gate l-QERL Hae ay, to 2Jaeee Goer Vitale mies vom mine SO. OGG vid te: F)- joettuewe uot geansdit =) 2 @el Vic dey sveres of) Pa emge canst ED eforvia —_ Me -Satizoe So erlemeral esneius? a ad . ; “93 G7 wisy of ,cetoeje yw fatt wel ev 1 — a ~bRy hast fo ‘gees FrelerTics a.evall rposte eovhory saibel> B= 0b eho¢ aloe 160 aww ctcovmt sh tos oF elas . =. - erntvers « don Jet? tootxe an dove of tatelq 7 Tis ot te@itosa ad Bives fou to Moal ,%mo20T4 etsw Toven tat, tidedois aid? ~tavewol oases dont Systia ats —— suniood s1etaw to nl betwood i < ' Q038 al eteteyo Wlihs io efodesd nofi{tn Leneves 1 paaatagcal eted = iives edd to aote edt 2 STOTSteny ,7omeo eW /etoenmwags “gon ; om aft ~aisearmaae: SaNE9 B&B atenwage bf Hoof efi? 268 to tonto o ~— Yo. stuftal edd 2aet egos wl ~ffet wid sot NoOenet a te foonsvba’ sd blue @s02 ni. dost To _aiiten - ah @teisxo Ic "en ; Wtav Todesh on Rb Tat? sone stan “aie ae _ $250 1.20 booe ee! eer Wal v | _ «eet teewrends tm 8 cia? fade seen aihM There is no reason why the oysters in Long Is- land Sound should not spawn annually, Our records show that the summer temperature of the Sound is always high enough for the development of gonads and for inducing spawning, In depths up to about 40 feet a temperature of 20.0°C. or higher is maintained from about July 20 to September 15 or 20, i.e., approxi- mately 55-60 days, a period long enough to permit the oysters to discharge their gonads completely, Even at the depth of 100 feet the temperature reaches 20,1 or 22,0°C, The mjority of the oysters complete their spawning by about the first of September, approximate- ly 15 or 20 days before the temperature begins to de-~ crease below 20,0°C, (Loosanoff and Engle, 1942), Thus, failure of setting in our waters cannot be at- tributed to the failure of oysters to develop gonads and to spawn, The failure of some aquatic species to propogate has been explained by the reason that a large number of the eggs discharged remained unfertilized and later perished (Thorson, 1946), This explanation can- not be applied to our oysters because, in their case, usually a large number of. individuals spawn simultane eously, and this mass spawning insures fertilization of the majority of the eggs, On several. occasions we observed spawning of oysters on the shallow bed of Milford Harbor, During the spawning the water over the bed was rendered milky with the discharged eggs and spermatozoa, Examination of the eggs showed that all were fertilized, thus indicating that there was no appreciable waste of eggs, A similar situation probably exists in the deep water beds, It is doubt- ful, therefore, that failure of fertilization is a cause responsible for the production of the small number of larvae, On the basis of the presented considerations we may conclude that in Long Island Sound a sufficient number of oyster larvae is produced each year, These larvae are planktotrophic with a long free-swimming or pelagic life which, in our waters, is about 18 days, Larvae of this type, as Thorson (1948) points out, are "Cheap" because the eggs from which they develop are small, containing little yolk and, therefore, they can be produced in extremely large numbers, However, the initial advantage possessed by the oysters in produc- ing a large number of eggs and larvae is counter- balanced by several disadvantages the first of which is, perhaps, the long larval period, During this period the larvae are exposed to the attacks of their enemies and are entirely dependent in their develop- ment upon the presence in the water of certain plank- ton forms which serve them as food, Furthermore, dur~ ing this period the larvae are also exposed to .con- tinuous changes in their environment some of which may cause heavy mortality or the complete disappear-~- ance of broods of larvae, (-15-) Tt i] i { rs uy ri : i? Po i ote ) iit W pons Divot a a! fir Gaeet ne ™ ' F + (43 ft 7 fy i etyrintti ty io f ' it =f i? San) © | ae» ? T 51 | tr a j n j ’ “ tae ey wo 1 a i | ae ? +n GO ij f ! + of¥arak _ ‘ a: Wo | Tei 3 ; Hl vl eo ‘ - ek oc 2 , watt Bem dolerd 0s etolyyo io 9 Flaster oa oy fs E vg ad l : “hia i i ’ iv art of t ietl > an i rei a if & baal l re Oy . | pile FO ecal j i : ie) hg 6% Sa 4 iT r Rood 2 ; oy mete f TO re r) fe, hp vii But ea 1 T= 7 J is ta 5- Dore 7 a4 vO@ Bottaess Lew wa ; vib rot =m ’ had wollte +4 . ) Tt lz t) TBI eu ts ant i 2 yaiqwd 2edtat Prot lin ‘ ee Ceneetstrh ate cs! tim Cotafirm, saw tnd ott . hi f Se € 7 a o _” ws A> “* - ar ‘hy + ; , > « ee aa: I é PEE;QGTGRE A. , > to ateaw eidetopitcqé on... St #2. sober gt Goeb ert). ot atetim yldadotg : ws me tt su te tert 4 + ar i, f. LAP : pwitnt iz e* wte7orl) 1 ah “fe Giese of) to tolvatbor 29 <5 oldhapoqeot ooveo “5 batt ar To " 5 COE - y 1 7 Pine 4 MWEnveblanve | Pro. ee'tey oc o @fead odd oO - ca SapSortiva « Grimgs bax [nd gam a2 Jad? ofc ‘foros A - ovat? (ae doe oudotm af pevtul totsyo To ted SSe-e0t) pool 6 dor otdgotie+ inala ote esytal i “ R eb Jeoce BE e197 bW I D ft sfotdy ot&l otgsisq 10 e906 edoteq. (OOL) noe rout gs ,o7yt eid? to osvial ol gotevs } Yer? dobdw mort tase ent guveved "qaad)" Rag OTe wed ins dAfoy si7vstl aniaistvaoo eee f 5 . ,teteeol te dost satel cfematdéee ct Forde 4 5 ov. “oulbotg ni ete ceye oy yd berese20q eyetnsvbs a “te tout: ¢t paviel bons ezye To reduua satel. s. > festt at eousomevboath Cateves ee a tye Reg to tedow alt nf Serer t: at bb tone sit zit ,too as mad r- 2 =@o0o. of t+ coqxe ese i Sarees acu a. a ‘o ex ‘selene sashes ws y ais Before proceeding to discuss the conditions that may, or may not, be responsible for the mass disappearance of larvae we should, perhaps, be-= come familiar with the major events of the pro- pagation of oysters in Long Island Sound, In the past a rather complex formula was offered for pre- diction of the time of the beginning of spawning and setting (Prytherch,1929). We find, however, that the situation is less complex than it ap- peared to earlier investigators, Our observations showed that spawning in Long Island Sound always begins either during the last few days of June or during the first days of July. The earliest date of spawning recorded was in 1945, or June 26, and the Jatest, in 1937, on July 3... Thus, dnjiwelve years the beginning of spawning was confined to a calencar period of only eight days, We may be justified, therefore, to conclude that in Long Island Sound the beginning of the oyster spawn- ing season should be expected on June 30 + 4 days, The beginning of spawning occurred at every lunar phase ranging from new moon to the last quarter, It was not related to definite tidal Changes and, therefore, to the changes in hydro- static pressure, The earliest beginning of setting was re- corded in 1941, on July 15, and the latest, in 1943, on July 23, Thus, in twelve summers the beginning of setting was confined to only about nine calendar days, Although it most often took place on July 17 we may, nevertheless, suggest that, for all practical purposes, in Long Island Sound the beginning of oyster setting should be expected on July 19 plus 4 days, The beginning of setting also happened at every moon phase and was not confined or even closely related to a definite tidal condition, The formulae offered are based upon our observations which, I believe, are extensive enough to justify suggesting them, They should be found correct in the majority of instances but, nevertheless, we do not maintain that they should remain forever infallible. Some extreme- ly abnormal conditions, not encountered thus far in our experience, may either hasten or retard Spawning, or shorten or prolong the larval per- iod to such an extent that the beginning of Spawning or beginning of setting would take place outside the limits given in our formulae, The setting season in Long Island Sound is of comparatively long duration, It usually ex- tends from the third week of July to the end of September, and sometimes even to the first days of October, However, the intensity of setting (~16-) F = , sea bo hina. ity fred ‘Wee ado Te ~y tal _ : ers § 7 a. ont eT pil itt i } vient ve! Oe Com pee LZ. aveh vetmeicn onta , eH oy eS Vint ao soaiq- eter 2 ui Lestinem Lf6 qot .fass | 6 Bidens wiihte- ave lo entantwed ont favod ~ \itiontead act uyeo # ng Iq er vil Do. batooqgxs bas St ihe avout erove 3% be acy etl Sele gnitios Ic » * at Metalot Ylonlo neve to Genftnoo fon e2aw iy oldthnoo Lshtd otintteb. tan nog i. o> eufpmieT ofT eno? te 8 dotdw enciteveseda brvorts veut mS ri alvges (tts aul. of mguens : 4 iy 4 Joorros hier + od pie joven ,fad 7 Nahata i te Se teanionces Ton . ar ee Sewwen eh to fb!emt toftioa vie inen we «2s aie’ + event oi3 Atlee Lore ie t a to : yatboh ged we fond so0vay/ oiled Sirov jrtsves tp ait -Saliettol We al “ear “at Prot “Weaker patad -~3. Uf fauey sx; Bie) rt oy a are >, ee : er in time does not follow a rigid pattern from year to year but shows several variations, For example, in 1940 the first wave of setting was extremely heavy while the second wave was relatively light, In 1942, however, heavy setting came late in the season as part of the second wave, In 1944+ setting continued almost uninterrupted during the summer but again the first wave was much heavier than the second, Final- ly, as in 1948, there may be two waves of setting of almost equal importance, In the latter case two distinct waves with pronounced peaks or maxima were especially well demonstrated, The date of the peaks of setting showed no Tre- lation to the date of the beginning of spawning. In twelve years of observations the periods elapsing be- tween the beginning of spawning and the day of maximum setting of the first wave varied from 16 to 40 days and averaged 30 days, and the beginning of the second wave varied from 47 to 66 days and averaged 56 days after the beginning of spawning, In time the date of maximum setting of the first wave varied from July 19 to August 10 and the second wave, from August 25 to September 12, These variations show that it is difficult to predict with any degree of accuracy the dates of maximum sets, In search of signs of periodicity in the occur- rence of the peaks of setting the number of days elapsing between the dates of maximum settings of the two waves of each year were determined (Table 1). The number of days for the year of 19365 is not shown in the table because the late setting in that year was a complete failure, The longest period between the two peaks was recorded in 1937, when 53 days elapsed between these two events; The shortest per- iod of 23 days was noted in 1944, In the remaining years the period between the two peaks ranged be- tween 28 and 38 days. Thus, as can be seen, setting of oysters not only varies in intensity from year to year but the peaks of the setting also do not show a definite time pattern, What are the conditions responsible for the survival of larvae and, therefore, for variations in intensity and in the time of setting? Because our voluminous data are still not completely analyzed we can offer at this time only a general discussion of some factors without a complete evaluation of their importance, We hope, nevertheless, that later on, upon completion of a thorough statistical analysis of the mterial already available, we shall definitely establish the presence or absence of correlations between some of the ecological factors and intensity of setting. Temperature is the first factor that always comes to mind when considering oyster propagation. (17) 4 e AC (e600 OF meh Ge RHE? .eych JE fne SS opawt tmial ai seltay er . wer oid len ‘ ' ano rT Ph . he = “LS Sat 7 SP1sv at 7o'ted?, fe oavesl Yo fnetviaie® giv = a } a PL ASBM LSE anil: Number of days elapsing between the dates of maximum setting of first and second waves, Long Island Sound, 1937-1948 YEAR DAYS YEAR DAYS 1937 53 1943 --~ 1938 30 1944. 23 1939 36 1945 28 1940 31 1946 34 1941 38 194-7 32 1942 38 1948 37 es) It cannot be denied that low temperature prolongs the larval period, thus exposing the larvae for several more days to their enemies and other unfavorable conditions, However, we do not think that fluctuations in temperature in Long Island Sound during any particular summer or, as recorded dur-" ing different summers, may kill the larvae, The old conception that a sudden decrease in temperature of 2 or 3° would kill the larvae has been disproven by our field — observations (Loosanoff and Engle, 1940). Recent observations at Milford Laboratory by my colleague, Harry C, Davis, showed that if larvae kept at a steady temperature of about 22,0°C, were placed directly in cold water of about 8.0°C., and after be-~ ing kept there for 30 minutes were again transferred back to 22,0°C.,, they would survive this treatment, even if it was repeated several times at two-day inter- vals, The work of Sparck (1927) also showed that the larvae of 0, edulis with- stood quick cooling from approximately 20,0 to 0,0°C,, and were even able to survive at the latter temperature for at least 24 hours, Obviously, small fluctuations in temperature, as obser ved in the summer time in Long Island Sound, should not result in mass mortal- ity of larvae, Although temperature may affect the larvae by prolonging their swimming peri- od or by affecting the quantity or quali- ty of their food supply, no clear-cut re- lation was found between the departure of temperature from the mean during the periods between July 1 and September 30 and intensity of setting, It is interest~ ing that the heaviest set of twelve years, which occurred in 1940, was during the year when the temperature departure was considerably below average, It is em- phasized, however, that a further and more detailed analysis of our data may indicate that although no correlation between tem- perature and setting was noticed when long periods were considered, certain correla- tions may be found when the data are ex~ amined on a monthly, semi-monthly or week-~- ly basis, The changes in salinity in Lons Is- land Sound are so small that they certain- ly cannot be regarded as responsible for the mortality of the oysters, Roughly, our salinity range is between 25,0 and 28.0 parts per thousand, Usually the changes in salinity of the water for the (-19-) * + coy z , os * = P . r ? ba SPF j 5 ; } a" Si r i ‘ ap 4 | } 2 i> f bt ‘ , vd vo: ’ & d r) is fig 4 . Vora sl Oterlen Y : 7 iy, 4 : a é XZ aves. 4+ 7 + 5s £ Tea P - _ Civ Oo it #4 — —_ a , ‘ “Ou ey oe Pris t , 4 mians. oseyv marred OF rn, .. ae - oy A wee { Ty i ey 17. %% maw |: ray : J oT ‘ iy 13 ~<«{3 1 “ 7 guy \ 2 . ¢ s~) 5 i; a a i = fm b en hyp] ya r re ‘ ! if Vi ’ 7 oe | 4. } é : mt aA rf aor. eT " J le : ui 1S a ST S's ‘ ‘ ol Th stimatoe Shears “kink tz val iadip a> od a * e -, 6" Jco~-terls Gn .ul midiegeh eee a ose re ivwtrs rhe 2 T60Y oviswd edt antorb Rew omitagoh “<% ¢2 3] egeitove otem Bae tedd tt a2 Parti : etJactihat ve SBy8D “WO 2 tie 7 ito wo 34 s gle ri i - ‘ pmol feaw Dbeotson aay ~efotven niafaee , tet -%¥S at8 ofnb ef rece ; we - —" ~ = ASS 3 af al imps > ; 5 = * of -“ cam ~fil afro c Je ofdiaande “idauell De: ” Faun 0, oT ATS o pancho i noitaletis5 ab vétaifee at este > yeriz sb aid lems o¢ s an totes aRwIeVO. oll foc 7 y s “+ } ' , wi - 12h 5 ro ‘ ; of a' s) hd 4 OM , ~ 1 b ou ev - iy dcods 7 LOO “at rus! 9 ast 5 eal f pana ho » H ’ er ue } ; : 2] ¥] avivrtite Ey 7 a i i! . 4 Tt ? »| >t a ba ‘ ry I ay 3 , iis « ) | } & > iT Ye - 4 ° Pal ae iy=3 f 1 qf } Pre Prowl ' { hey r? elo Pa tt st aot | ) 7" i? } Wz 4, in pototm- i osvral ad LiceTtia wd «9 Ba 7 wens 20 ) Oe rvo2 Trew riots al stiseteqn? To sevted bo Etaq to Vetanosiat boas Viet edd Jad? ant Lgl Seztvoso jhet ants fonw TASY . of ric istohlanse ‘ 122 | § boftstod das ; pustemes on a aivtives oy Re etow abolieq havo? od Ya ena a 2 Hort sekrtw ‘ i _«Doate aig efit? om & mo den! : -atend “ft rd - 5 same period of the year seldom exceed 2,0 parts per thousand, and not in a single case did we find that the salinity for the corresponding week in twelve years exceeded 3.0 p.p.t. However, although these changes are not great enough to cause mass mortality of larvae they may, nevertheless, reflect on the pro- duction of the food on which larvae exist, ‘This phase has not. been thoroughly investigated as yet, The percent of sunshine during the breeding per- iod of oysters should also be considered as one of the factors which may have an important influence on the survival of larvae, This, of course, does not mean that intensity of light itself may kill or stimulate the growth of larvae, Its effect is largely confin- ed to the growth of plankton forms which may serve as food for oyster larvae, Again, preliminary analy- sis of the data showed that in Long Island Sound the intensity of setting for the entire season was not correlated with the percent of sunshine during the period from July 1 to September 30, Nevertheless, it is possible that later on, upon a more detailed analysis, some correlation may become apyarent, Since, at present, none of the above discussed causes appears to be dominant in causing mass mortal- ity of larvae, one, naturally, turns to look in an- other direction for an explanation why larvae dis- appear in our waters, We shall discuss two of the possible reasons, the first being extermination of larvae by their enemies and the second, death of larvae because of lack of food, There is no doubt that a high percentage of larvae is eaten by their enemies, and that, in some cases, the presence of a large number of ene- mies may be the primary cause of failure of oys- ters to set, It is doubtful, however, that the failure of set in’ Long Island Sound is primarily due to that cause, Were we to assume that oyster larvae disappear because they are eaten, we would naturally expect to notice a similar disappearance of the larvae of closely related species of mollusks, such as clams, mussels, teredos, etc,, which live in the same environment with oysters and have the same enemies, Our observations show that this is not the case, During several summers, including that of 1948, while oyster larvae were relatively few in number, the larvae of all ages of the clam, Mya arenaria, and of some other lamellibranchs were numerous, Furthermore, while the oysters failed to set in extremely small numbers, heavy setting of Mya and mussels continued throughout the summer, Thus, since, regardless of the presence of common enemies, the larvae of many lamellibranchs survive in large numbers to the setting stage, we should expecta similar rate of survival among oyster larvae, This, however, was not borne out by our observations, (-20-) We all know that in the southern states the fouling |: of shells with various organisms presents a definite pro- = blem because these organisms deprive the larvae of set- ting space, Most of these organisms are also larvae eat- ers, Furthermore, in addition to the bottom forms there - are large numbers of jellyfish and other pelagic larvae~ . eating organisms, Yet, regardless of such a large vari- ety and the large number of larval.enemies heavy oyster sets occur rather regularly, ; In Long Island Sound, on the other hand, the bottom fouling forms are fewer in species and numbers than, for example, in Chesapeake Bay or in the Carolinas, Although a few of our shells, planted in early July, may be found Silted by the end of the season, very few of them would be encrusted with barnacles, ascidians, etc., as is al- most always the case in southern waters, Obviously, the larvae enemies in our waters are not as numerous as in some other areas where good sets are, nevertheless, pro-~ duced regularly. Thus, even if the larval period in our waters is longer than in the South, it still is improb- able that the failure of our sets would be due almost exclusively to the activities of the larval enemies, I can cite another example of the same type, In Connecticut waters the best and most consistant sets oc-=- cur in the small, rather well- protected area of the Thimble Islands, The slopes of the shore of these is~ lands are extremely heavily populated with different organisms which are plankton feeders, Large sections of the bottom are aiso heavily populated with larvae- eating invertebrates, Yet, regardless of such a pre- dominance of enemies the oyster larvae there survive and set in large numbers, while the Sound proper experiences one failure after another, Obviously, if larvae enemies were the chief causes of failure of setting, the Thimble Islands area should not be a good place for the propaga-~ tion of oysters, We may conclude after the above discussion that while the importance of larval enemies is understood, and while it is recognized that the damage they do to the popula- tion of oyster larvae is rather extensive, it still seems improbable that in our waters, where the larval enemies are not as numerous as in other oyster-producing areas, failure of sets should be ascribed mainly to the activi- ties of these enemies, The final cause which we wish to consider in this article is that of lack of proper food for the oyster larvae, At first the suggestion that under natural con- ditions oyster larvae may perish from starvation in large numbers sounds highly improbable, Several years ago I would not even have considered such a suggestion because I know that, as a rule, the waters of Long Island Sound are comparatively rich in plankton. Yet, during the last few years, especially since the work on cultivation and physiology of oyster larvae was begun at our labora- tory, more and more evidence is accumulating that oyster (-21~) ? ] > b 8 % “ eth ver ost ei oF "io- "20 OL? nigh She oe! — ety pha di : partes nas + eeahT To ‘Ser ‘. banet or de << larvae cannot utilize most of the forms of ultraplankton regardless of their small size, A more detailed discus- sion of this subject will be given to you by my colleague, Harry C, Davis, who did work on oyster larvae, while I shall limit myself to only a few remarks, It has been found that the addition of mixture of laboratory cultures of ultraplankton forms measuring from 2 to 5 microns in size, thus small enough to be swallowed by the larvae, will not make oyster larvae grow, Apparently the mixture of plankton given to the larvae did not contain forms which could be assimilated by them, Yet, the same food given at the same time to cultures of larvae of other lamellibranchs was readily utilized by them. Thus, while, regardless of the pre- sence of numerous ultraplankton organisms, oyster larvae refused to grow, the larvae of other species of lamellibranchs thrived on the same forms, This, of course, indicated the inability of oyster larvae to assimilate the ultra plankton forms which were present in the food cultures, I think this phenomenon is extremely well il- lustrated by the expveriment which I devised and which I asked my colleague, Mr. Davis, to perform for me, Last winter oysters and clams, Venus mercenaria, were made to’ spawn on the same day but in separate con- tainers, A day or so later, after the larvae of both species had reached the straight hinge stage, we placed the larvae of the clams and oysters in the same container and began to feed them with a mixed culture of laboratory-grown food culture containing a large number of ultraplankton, Three days later the clam larvae had grown in size to 1054while the oyster larvae were still 754, Five days after fertilization some of the clam larvae were already measuring 1254, while the majority of the oyster larvae were practically at the same stage as at the beginning of the experiment, After eight days the clam larvae were over 140 while the oyster larvae were still between 75 and 80the majority showing no growth whatsoever, At the end of the ninth day the clams were growing very vigorously showing almost no mortality and measuring about 160“while the oysters were dying in large numbers and those living were still measuring only between 75 and 80“, After 12 days the clam larvae were finishing their free-swimming period and were setting in large numbers while all the oyster larvae were dead or dying. None of the oyster larvae were longer than £04 Several variations of this experiment were run to be sure that the oyster larvae were not de- prived of their food by the larger and more vigor- ous clam larvae, To achieve this some cultures were composed of a large number of oyster larvae and relatively few clam larvae, Regardless of the (~22~) “== ¢ a i or 7 Ps ve fat tn Psy ~ ) in core Oo a 2 a? -* m46 povia % ~Gnogst) . a t-d in so] hi ne “iudtd To exe lhtagst ; P20! due ’ To nola. jolete mnt iat i, ti teysy Saot-aas GE LZGOr! Sao Yr ili eney yah it , ents » SARDOA, For rc IRR Leers! Los i lo ean9ae We 1° & ; : becvlet Savriel . sSewst Sane sa? no os). teigietd fifc ms fasiete to Yitildent eft? SJpalir?. ,ctwed : 960: Asa sade? coficata ellis of ever leruse Sets fis (et uilt oF a ek a chaos : amammonilits, | ¢ Rats c j - ara i ‘ *e , ' 9fe roi a ue rane Yr. ony ( S ae ot ; : . i i a Fi nivel 6 rue i L& v j I 7 Tx rp! r ¥ bd A | 7: ; ‘240 : iM aut, nd F ; > i Mf = ee - 3 ae ae 3 o¢ sf ar MR, ORT PERS es xb 30< Lav eavtal x: ,woty * O2RLA Pete if 1 yitie wie Belisosd i bets Sv ae taut bots: faaajne.. el sofa asia er anette outing te \ > ol ir: no Syiwaive "ns WoT 4 Soviet Seuse. “(90056 To saveel) any ses is ! ‘A & OT Mo as, rugs a} det foi ; ifr ao tl i vas sev itec? ath s fo Te Wiinvicw =f-oW < ETON .% WwW , . raf wmeignvy.! A) eel sedtat acl tt: | arora te tie ay Powe) Site sp’ P< 9/5 ey’ fet evo we pail ea TUDDL Taito 6° “pony . tant add we oe wee ims reth x - Fe SHeTeLO 4 ey ct cin ‘ys By , Fel a os 1S a fe 2 al aw .*? ai 3 Pay $204 Blade Site swchaxyr2-o10 le on womlateog aod Hebd Ge3a09 Be, $2 EES Br . ) peo Rtey to Willis eff at Etisal Bis ‘cm etc? APeW SAT ff bevot bot ad? » d 7 at Zep l Toot m Ons Airy * st Sofeaivecrnt vie ad ,cfquseco WT meg @tesyie Teele Jf Prime Panul'ei erer of ano®tslh. ; SOY teouls ote tauste Lfs te eevier fo elidw des tdiw weoqiseth of ames oAVERE sere . tects ons. grt wh - - -@2 sl” 95g Sad mort Sagat vse sotte wyeh wots wt 7 ost att oF gub ef o onatesggaetb Sidy ta: eee Go phi tdw boot s@t Jost erasev te sbotrs¢ : wont s aes pat * Tead tad JL soute foav7: of tofeyo yd | es bene: 5d ms9 a eintalteqas Yiorsisisl wo yd De Sorte b eit nafs Ser is Ws emtot urean etifiic of siden oth on tar taTEYO “ 2 of 7 a —_ 26 s0ngECcSs atid Jai Megha Mis) atwtt 7 on To Gal : I ogad nati¢oae of7 ot ays fC oF GriucS feetel po woe wont 0 notin 4GC art ft: rw 2si tot rioo iat li bas rei “aL pat videdo (a al Moot fo steel tart eslabdtt getn ortw (drer). atid to enolseudoult suit rot «€ rdteroge Tr oozaet sone & , aoe edt nt sole MOE : ape aim abt sokvetio or? 18% Urey axe Lite dy onauos 0° Pp tq Sond rogat kyvw tdeowint els 3 Teves ak 7 vera: st [fits 3t eee ve Saad ont a2 F, ft. We ‘ Be Sa bent Saale ie oi fio ; a2 £ 7 hig ; Vat only eseeags ed? , ¢fixroos rte aie mete’ iy ad: Many gta pot fav ' OTP, 86. Mund. ROTORS Las ooh a temperature, solar radiation, presence of certain nutri- tive substances, such as phosphates, nitrates, etc, These relations remain to be determined, and all the data should be more fully analyzed and studied, Nevertheless, I think we are now approaching the solution of the problem why the intensity of oyster sets in northern waters varies so great~ ly from year to year, _BIBLOGRAPHY LOOSANOFF, V. L. and JAMES B, ENGIE, 1940, Spawning and setting of oysters in Long Island Sound in 1937, and discussion of the metnod for predicting the intensity and time of oyster setting. U. S. Burj Bish,, Bull. 33, Vol, +9, pp, 217-225, LOOSANOFF, V. L., and JAMES B, ENGLE, 1942, Accumulation and discharge of spawn by oysters living at different depths. Biol, Bull., Vol, 82, No, 3, pp. 413-422, NELSON, THURLOW C,, 1928; Relation of spawning of the’ ene to temperature, Ecology, Vol. IX, No. 2, pp. a 5-154, PRYTHERCH, H, F., 1929, Investigation of the Physical conditions controlling spawning of oysters and the occurrence, distribution, and setting of oyster larvae in Malford Harbor, Connecticut, U, Ss, Bur, Bish? Bulls, Vol. 44, Doc. No, 1054, pp. 429-503. SPARCK, R., 1927, Studies on the biology of the oyster II, The feeding and growth of the pelagic larvae of the common oyster (Ostrea edulis), Rep. Danish Biol, Stat,, Vol. 33, pp. 46-56, THORSON, GUNNAR, 1946, Reproduction and larval develop-~ ment of Danish marine bottom invertebrates, Mecdslelser Fra Kommissionen For Danmarks Fiskeri - Os Havundersgelser;) Series »Plankton, Viole i, spp. Hae), (-24-) i) aye ‘} : ‘ é “Axacs ales or nents eohiathes. afew peceyetaqmed ‘ > ERY 0 pte soeite 1s ine , eoansiedua eves tf: : ; es hea edle cE ' a 4 ef, nis m7 yeleee ive =. Pbk evixzns i? atom ation aut Ae 5 Sale: oY OBIFu Teer anidosomgs word eB SW mi goer wiayo to yttenssat . etHOX oF te0y sort Tf r Te re ul hed dV UOWALDOL fi at gradaye to sat Tie anwar off to nolesioekd )nmeotae Taster Yooomts fra , SNS ES .@2.,08 .f6V ee 0S EM, Bae dk WY , TOMAZOOL “Avems . TS agtordoets baa & ov is | BEY 4 10g mn nitsy md acer, > Mle WoarIaen — ,2 4) nue: OF 197 Per APR ne { Wohets oplzenve: jeter ,.% 8 jimaiervas %6 ontowers sotraecatin =f. femmes 2 ! een Sae -moisedirsa hh HRTTEIe9 , iL fusliiooane eine = S2ontin #2 afi we ay PeOE oh , 208 yee ufar ievase ett y tiooss ton 9 sftegt gat mee 3 | - aRead. oa A ste qetele s,OLe datont tor /- Se ies bag Mpesoubotqes «3+: nae ‘ io ener rs dubosa'3 $a base a Parte 3 i” +) Teh ut ise gl tire oes 5 aah hat a eelands ‘TH a PLANS AND PROGRESS OF OYSTER INVESTIGATIONS IN FLORIDA ; = by- Robert M, Ingle, Assistant Director - Oyster Division, Apalachicola, Florida, ak ak akc akc ake 3k The great decline in oyster production of the State in latter years prompted the 1947 legislature to appro- priate $100,000.00 to begin the rehabilitation of the oyster bottoms of the State and to encourage greater — harvests, Dr. F, G, Walton Smith, Director of the Marine Labora- tory of the University of Miami was made director of the newly created Division of Oyster Culture to serve without pay, Mr, Robert Ingle, shellfish researcher of the Marine Laboratory; was appointed as Assistant-Director on a full time basis, Both men were given broad powers to make rules, regulate closed seasons, Although the money was appropriated in 1947, actual setting up of the new activity did not begin until February of this year (1949) when the above appointments were made by the newly nominated Superintendent of the State Board of Conservation, Mr, George Vathis, ; Progress thus far has been mostly in setting up a research program designed to establish some of the basic facts concerning the Florida Oyster, This survey will try to throw light on such subjects as these: (1) How long do oysters spawn within Florida waters? When do they start, quit? (2) If there are peaks in the spawning, can they be predicted, or do they follow any regularity? (3) What is the growth rate during each year of life? (4) What is the length of larval life? (5) How do the spawning seasons of competitors for setting space compare with oysters? (6) What are the optimum eclogical conditions, What extremes of salinity, temperature, etc,, can be tolerated by larvae and adults? In order to answer these questions a broad research program has been started with the center of activity located in Apalachicola Bay, A field laboratory has been set up and equipped in one of the local seafood houses, Nine stations have been established at which fall of spat, salinity temperature, turbidity and other hydrographic data are obtained each week, In addition, growth rate of young spa is being studied and at two of the stations (-25-) «at ae Pe aie fanart ae UETADTTOANEL RETO O ACsOOM MHL FARIS Poy * = Bt ‘ ie Pi i Se of ®@ hi 13 old *% 3s “2 Sur ee - yee, Pee jes Ee tik : rms, rt ome teal Croll 293 yuo! Size, 7 f ot ASM a@.( 3 4 et Ol gSid ot oA poesia! wv I . dq Oy ae x ) ww infhtel Yo wWikeieranl u: io. med Dy ems 3) sre\G \tG aitecv ee 726%: woo © 2% D? ~ Hotei lotls.« @arel waacod . TN ‘— ont ‘peo is bas 1 SFTP = ae 4 PeTOaG Rs os 697484 a) ' uel 4 ner SI0E 22206 BRia if : is i] sae. .tWfigd be ISPs = Sirow ode tf wOrlTtA ae ‘tan giegd Van Pir yriesss. | itd aq Sf wastes Oy mm eel se cw ft oo [Lik i? 29 Vs ws. 7 Ww Tree P4erO il 29'Ti- Pee ; wa ww F vast wo ,gttaveds oi, ob -ofeeg ota aiecr IF {Ss} fasluget wortol yedt @ siottieay’ | 4 20 tone sioea Pita) 4%e0t 4 OR ait- teil? Levtrel I wewodiongqnos | Wo 2068501 ‘¢ ve”. pavo id bw 6"! woo. I wo l7 26 tg the growth rate of larger size oysters is being care- fully watched, ; A weather station is located in Apalachicola which enables us to correlate facts obtained from the nine stations with meteorological finds such as air tempera~ ture, wind direction and intensity, precipitation, Metcorological data for a period of thirty-five years is available to us in judging the normaley of the weather during the investigation and, hence, whe- ther or not the findings of the investigations can be deemed typical. In addition the U, 5, Weather Bureau, maintains a river station at Blounstown, fifty miles up the Apalachicola River from the site of the investigation, Accurate data is obtainable from this’ station on flood stages, rate of fresh water discharge, Thus we can surround ovr studies of oyster biology, especially spawning, by quantitative data on a great muber of physical and chemical environmental factors, even to the amount of sunshine received by Apalachicola Bey. This information, as it is received, is translated into constructive measures for the rehabilitation of the oyster bottoms, For instance, the discovery that spawning occurred much earlier than was anticipated has enabled us to beging the planting of cultch at an early Gate with the assurance that it would attract a substantial number of oyster spat, Also, Since spawning occurs in a greater density in different parts of the bay at separate time we are able to adapt our cultch planting operations to the areas which enjoy an intensified spawning during any particular week or month, Coorelative studies are being carried out ona smaller scale in Cedar Key, Florida, a location at some distance from Apalachicola on the west coast of the State of a latitude of about 60 miles more south- erly, It is expected that there might be slight dif- ferences in spawning habits of the oysters of this region due to greater temperatures on an overall, year around basis, although this contention remains to be proven, Scveral experimental plots of seed oysters have been planted in the waters south of the Suwanee River to ascertain which of these areas hold the great- est potentialities for oyster culture, It will be interesting from an academic stand- point to compare the findings of this investigation with the knowledge already available on the same animal in other parts of the United States and Canada. (-26-) a . o — e a ateo. 4nind a) aist2yo oaie tw yicl ‘to odar diwote ed aan tetosew ylisr pete afodidor t basedoal si societu tertyrew A | in. a7 wrt lie pian? aoaleinng 42 2b er yer ¢ Oo wsret sébetet ARO OF HIECi Leve st erssy . = P » ba , - pet, a) uo Lanier. ot. (its tetteaw ets 9 IA > 7. 2@ na* vO at TE egal wait ais 2 » tox? bemes 5. 7 -~ > g ’ _ >» : i taale e,.g0t) ¢-! TLS Y vie ack ¥ is be Benth we wileeda-eene mast eifieniaice ef meh ptetiook.: ak adele a fst? To : gee Waclasd «as i watts s2 a6 Waintwape neo ev audT > | ; gen ae to hay. avg! yt ecw or wt Tot seatsa’ @ é mm ta = vy ggaevels On & i ee, 729 emcdcut {eonaun ete’ = Saotoscs weet 16 ta aboat: forge) “SI tee > i; s 30 Tne. ay oo fave Ll : IBS & Seyertulin<. ay « Ttaa col TT NGO ees ee 39 ny?iese SS wes Y yah auiteo d of fo teane: gad 4 Sarason tincy tk 3 “aes of() Oo LW otad eis [iva far: iz woes rade : Tisms $plpaty |r GS SVS 2 are Revi: onte~ oc fh co et4 ev auld sJoterpys f= ea inte ba) a | ‘ten taTtte: mE « ome ot BND LR gO ptsc@ hp, gar f> Hag or od aide wie snivwb gilneqge Ss lcregea? os youn dolnW spats goer 10 Meow elvolrrag Ss no Yio Extriso ycied. 2% BAlhors ovisaloroo9 te noljsasol 2 pa Pelt Ae gntas nd efnoe tofiena tq JELOS snow. oe no al todnaeal sc & tt Sodsteth gato -_ -GiUG6s" 070K ao lta mh Rafimr.) i i) etry tT ol a To ojath -) “2th tigtie sd sigtn ote Sat? poh shoet pt 3t , vite sid? te wretevc ort to eaidan gain weqe nt ceo ak 7 ‘Seay. .[letovo ns no evuttatogiey ts wieons oy oub swalge ed of caseees polimetnos tho saved Ea ae ts 2107?cyo tee< to etolg Faso ae’: 20%S cree aa |: po eenawih at? to divor ote daw ott ns P nate Vi “tao%5 ett iio neers analy > alunos ft di ate Se) [70 i] — -hnots olen hon. a8 mort bo HOT FL stad sgh ait? to egaes bart on baie wT oto eldeltove ehserct ebboes 5 nears tad pe "e *y & . aa P But more important will be the help these facts will provide in actual cultivation, In February 1949 ‘there were only 1738 acres of oyster bottoms leased to private concerns, By consultation with interested planters and by encouragement it is hoped that this acreage can be doubled within the next year, Closed seasons, management, (including the plant~ ing of cultch) and close observation are expected to increase the yield from natural bars, (=27=) INTENSITY AND DISTRIBUTION OF OYSTER SET IN CHESAPEAKE BAY AND TRIBUTARIES Fred W, Sieling, Oyster Biologist, Maryland Department of Research & Education, 3K AC OK Ber The intensity and distribution of the commercial oyster set in the Chesapeake Bay and its tributaries has been studied for some years now by biologists of the Department of Research and Education at Solomons, the Fish and Wildlife Service and recently by the Virginia Fisheries Laboratory, Setting of previous years has been reported at these meetings thus only the 1947 and 1948 oyster set will be described. Ob-~ viously it is important to know what number of spat has set, so that future production plans may be form~ ulated both for seed and marketable oysters, For the purpose of this report, the Maryland part of the Chesapeake Bay is divided into three distinct areas, each having its own particular characteristics, These areas may be defined as follows: The Upper Bay is that portion lying above Sandy Point on the Western Shore and Love Point on the Eastern Shore, The lower part of the Chesapeake Eay is divided by the ship channel into the western and eastern half, These two- are quite different in their physical characteristics, The Main tributaries of the bay react as individual units and will be treated as such, The seed areas are sharply defined and have certain distinct characteris- tics which will be described later, Very detailed observations are being taken on each oyster bar visited and a standard form filled in by the biologists of the several agencies working in the field, These forms have been developed jointly and all the groups working in the Chesapeake area are making uniform observations, so that information ob-- tained in different areas can be compared accurately. In this way, there is being built up records of actual populations and the physical characteristics of the oyster bars, Many areas are visited but once a year, so that it is important to have as complete a picture as can be made at that time. Other areas, notably seed areas, are under intensive observation and detailed informa= tion obtained at frequent intervals is available, pee ae be discussed in some detail later in this report, The counts of oyster spat used in this report were made on one half bushel random samples from the oyster bar, Usually several samples were taken on each bar and the counts averaged, (~28-) pou bs Aaa, beat the re ig RT gaat oan 09 P < = — 1 Son uae rf aes | : Melis « ies Bie shy Be acod hen fysalt 7 ‘ ad | : a 6 lke oo odt £8 geltoliesesh Gro yt iecectat: adT TieGi1) ofl ae Lot ae on) @h Sag ratevo te ae lobe yd wing Smee 20%: fal iede eed. part a sEnomolet J2 raleeeee Yor artepeol to too tae aiff oo Sit A ¢tiveted Mae wakvyel s*200F2N dns tht, cult aio t vec ® Yerocatodas setvenas§ dinigit? ; geo 7 befrc-794. pend nant ys, : ey Sek eatsxc Dual Eno tyo vane oo goat voant af 2 ‘eta waky A. BUnosy etudir Sad of 4 Jos aad ats eeiten bie Iooe mG) god bospry fe Pals exit oc ~eanget eit 26 e809 tig man eetns Gagt feotrytb at Vl onfoyre en Reveetwi«s “eli/aisiny av Br anivet since ; Se r.wital aa ie altoh’ ed vas Sania | waee ees PO Seto? "onas eweta gntyl peitwog 3 at? x eres Mtetied ody nn ralna aval iyie side ia ©. fp ed babies ns “Hi ¢ went) of? to T tag 7 eet | etLoal at? tac ctefsuv odf>etnt fennndo, ) wont fenis ~ te tliggld ak weepveTila.seiuo ah 2a rate vase day. to a2eltaziaiiw ela ect Se glint? dQ Satepts ec Liiv fas etiau fontads Poukl eid alciiee ever o twaktul “fcuade “suetol Latisesh ed Lliw daidv toty.. 3 wuotvavieada be tiesen wee nf HLERy an (bacdeat S Dow Delielty tod tefevo Moss Soret setempas Laiovwe atl I> ava wages alt yd entot Bedo. rg SV onoort wed Glory art? os 5878 odtegerago ons at galvienw equody ald ee aaa 2. ‘wGO colt currotitt wale 3 ameoiieyionde mpmtini pikes eUfetemoas betagico 3 tae beats Sostett{y ab bentalt APs, » , Soe Yo ebzocet qu Jifvd yated ci salt, vow eile al in edt. 48 pila tdcike min od Saale pty od San enotiatiqoy oa *) i a sated tedeyo . 5 Patterns ae fone tod pedtery o1s eden wa -\ | Ned’ ae aiurtak ese! poe rs tossioqur et 22. “Stee bese yidaion /ereis J fen? te eheat - -artdtnt baftesed fis ican oe evisnstnt toh at ,oidefltevs st eievisint Snovpes? o6 ber aC 7 that oh natal Liatotr eae atk bacanaud' , ie . ” : ' ae a eeeysty Sth a mo .aty Most of the Chesapeake Bay bars show a rétiarkably poor setting record for both 1947 and 1948, However, if the record is broken down according to areas, it will be seen that one area, the eastern shore of the Bay from Love Point to Tangier Sound had a rather consistent set- ting record, Several areas along this shore’show sett~ ing characteristics comparable to seed areas, ._One such area in 1948 had a set of 743 spat per bushel on natural culteh, The figure used in the following averages were de- rived by averaging only bars which were visited both in 1947 and 1948, The average set on the eastern shore side of the Bay for 1947 was 61;2 spat per bushel and for 1948 was 15.5 spat per bushel, This figure does not include the two high setting areas visited in 1948, These counts are too low to make good self-sustaining bars, The western shore of the Bay has an even lower setting record, The average set on bars visited in both years showed a set- ting average of cnly 2,2 spat per bushel in 1947 and 3,4 spat per bushel in 1948, The upper part of the Bay in which ten bars were’ visited both years showed in 1947 an average set of 5,5 spat per bushel, In 1948 this figure dropped to 0,3 spat per bushel, These figures show that the future populations of the upper and western parts of the Chesapeake Bay, barr- ing an unusually heavy set, will be of practically no com- mercial value, This low setting rate combined with the low population level presents a very poor outlook for the near future of public oystering in the Bay proper, The bars mentioned are all Bay dredging bars, In general, the 1948 setting record was even lower than the 1947 set, possibly reflecting the general lover-~ ing of the population level. The picture in the tributaries is not good, but it is materially better in most cases than in the Bay proper, One of the large producing tributaries is the Choptank River, This area has in the past been largely self- sustaining but the population, level is being gradually lowered, In 1947, the average number of spat per bushel was 28, In 1948 this figure fell to 9 spat per bushel. This set will not add materially to the production of the river, The tributaries of the Choptank are, however, rather heavy setting areas and can be expected to contin- ue to produce, Tangier Sound, one of the important producing areas, Still has a good population of mrket oysters, These oysters are predominantly of the 1945 set which was ex- cellent, This area in 1947, excluding the seed area of Holland Straits, has an average surviving set of 45 spat per bushel, In 1948, the set was slightly higher averag- ing 55 spat per bushel, Tangier Sound has many very ex- cellent tributaries which are heavy oyster producing (27—)) — iy guivtotiws me ,foe Terr ont nadt @ Mel rolieincsw; ect Ip snt iE dud 5 sf “09 Jon nt val Prt = ay re a | 7Olu eat pig “Yeh ety mic = te sao pean ne ceived vilatyetem at $qor) @ac et golresidiny satediety ecia! od? 3. end Tiss yisgiel mod tia] ont ef Saf toys elit. .tevih cube cy aiiod. Bt fovel pols alaqeg ats J 7 piintes ave 7 Mevd 6g Taxe Io tsduun syatove ont 3 Cl nl ,Sergwol eri aud | Tow Jeqe © oi rd Paha: 4 whit BvOr nl .8s- he nr "to pelos afd of Ufletrsdom BBE for Liv toa eta? 7 wod ,evs duetqod) et? In 29 orratad ees fv sravtt od? _ itsioe o7 bod ped: *® bo C55 be 2251S anr?? a ryYsed 7 oT. v. sosbotg of ot e t= Lhe Ts yelovrhetq Jnesroqul edt WW ono »bouse eS sat O200T ,ccatevo foxtta i ta sotéalugqoa bass a eat Sibta, "5G etv dotrw 700 Gr@l on? Ye. OT pergroey et a ‘) este tose’ esd gal Phi? S30 Veet nk sete 6 a to tos gaivivew: egecee om aye tetgld elon heed one ch Xt e Tet aay) se 2 ide ic tse areas and which may contribute materially to the set in the Sound, These tributaries receive good oyster sets each year and are good self-sustaining areas, Pocomoke Sound, a fine self-sustaining area, show- ed a great drop in spat per bushel setting in-1948, In 1947, the record was 308 spat per bushel on natural cultch and in 1948 it was 197 spat per bushel, There is, however, an excellent ponulation of oysters on the small area of natural rocks, The Potomac River, excluding the tributaries, presents a rather discouraging picture as the popula- tion level is low on nearly all the major bars and it has received a very poor set during the last two years, In 1947, the average set was 10,8 spat per bushel and in 1943 the average set was only 7 per bushel, The tributaries of the Potomac River, however, present an entirely different situation, Excluding the St. Mary's seed area, the average set in the tributaries was 178 spat per bushel in 1947 and 86 spat per bushel in 1948, These records, again, cover producing bars and not shell plantings, However, there was a drop in 1948 almost proportional to the drop in setting in the Potomac River, The Patuxent River, typically a poor setting area, continued its record of low setting with an average in 1947 of 15 spat per bushel, In 1948, the set was even lower, being 7 spat ver bushel, Unlike some of the rivers, the Patuxent lacks oyster producing tri- butaries, The Patuxent must depend on plantings of seed oysters from the State's seed areas to maintain its bars in production. There is a low level of marketable oyster present in the population now, so the outlook is not bright for next year, The three main seed areas of Maryland bear a rather striking resemblance in many of their physi- cal characteristics, They are all nearly land-locked, have heavy populations of adult oysters and typically are not deep, There are many smaller potential seed areas which have not been develoned and utilized but which are now excellent self-sustaining areas, Eastern Bay is perhaps the largest potential seed area in the state, At this time only a fraction of its acreage is being used for seed purposes, It has a consistent record of heavy setting. Close study of this area is being made by the Fish and Wildlife Service, Examination of the shells planted there disclosed that the surviving set was 2002 spat per bushel in the fall of 1947, In 1948, the catch was lower, being 776 spat to the bushel on planted shells, Slag which has been planted as cultch in the Eastern Bay seed area for several years was found in 1947 to have a surviving set of 2280 spat per bushel, The 1948 planting of slag had a set of 944+ Spat per bushel. These counts are higher than those 30-) exit edt Stivts wdist oss 9 Ina "ww e5e*s di eats fogs syseras est at + Z eit pt , = « s aioe 4 — * yn & ts (4 ein = Tris at 2S 4 | wef ol Pek Gs 9 {per ? p t - Lae OTK? ; 0c | 7Nie * gaonl =F Vu > = Jz2C0Ls wo O4 ef?" he In FHOo { r 7 aD | * tt ol? Sirsswe "6 Geet ad ovat gon OTs eis Aoldv on planted shells in the same area, There is how- ever, a higher mortality in moving the spat on slag than there is in moving the spat on shells, due to the rolling of the particles of slag in the dredge which crushes the small spat, The natural oysters bars in the Eastern Bay area annually re~ ceive a good catch of spat, This area probably will be used more in the future by the State as a seed area, Holland Straits is a large area which is not fully developed at present. It has had a some~ what more spotty setting record than Eastern Bay, but it is a good seed area, The last two years were below average in spat per bushel, In 1947, the surviving set was 153 spat per bushel and in 1948 the set was 408 spat per bushel. There is\ a possibility that too much, brood stock as being removed and that an area should be estab- lished in which the oysters would be left to mature and breed, Such a sanctuary might, it appears, increase the average set materially. This area will be studied more closely during the coming setting season, The area which has been studied most in- tensively by the Chesapeake Biological Labora- tory is the St, Mary's River, a tributary of the Potomac River, This river has a consis-~ tently good setting record, but there is not a very large area available for development, The area here is much less than that availabie either in Holland Straits or Eastern Bay, There is an abundance of adult oysters on it which do not grow to a large size becuase, presumably, of overcrowding. The average surviving set in the St, Mary's River seed area on planted shells in 1947 was 1807 spat per bushel. This figure in 1948 feel to 788 spat per bushel, The natural bars in the river also receive a good catch of spat, Many types of experiment-~ al cultch have been tried here, including slag of three different sizes, tin scrap, broken plaster molds and porcelain insulators, Also, intensive observations of oyster setting and of fouling organisms have been carried on from June until September and weekly records of salinity and temperature have been taken, This concludes an area by area analysis of the distribution and intensity of setting in Maryland waters of the Chesapeake Bay for 1947-1948, The year 1948 was below average for setting in most cases and in almost all cases (=31-=) “wor el eter? noc2 wo att mf aflons Satnely no ff Taw od? gatvon at vwiiatvaw teggtd 6 .,teve Tera is oo Pets of? antvom st ef erate cadd sete ody at wela. te sololi.aq orf o poitiotr siz of ov - are eet. . ea 2 mc? eaters retriw onhott “OT wezelves B's ni S7uRi Of) WR e1sd Be iszvo ¥iteve ms me eld ite Te ogoo boo, 2 sviss Ue ATA Gy) Yd ome? one ae etom bea od. [itv . cata tesa a : iter ek daltulw sore otal * et 29 ris ad2 feonlfor ? ' “Og hiet _¢ Se eb e271 77 a heuc faveo ¢iiv2 | “at gesur? «+ erect galsiree VaJeqs otor? tafw : Tries, wr 732 ff ‘-_ To bee2 fou,y » er Jt sud wees at anne nee Saye a) soute%e woled e'raw San fou sgn Te? Jeg?» ERE saw fear Bi Viv riz edz a ud eq Toqe Hor aux toa oi GlOC ot ee 3 ae Poorcd feta O07 wo Wisissteeog « 22 wigiee cf ifpode segs on ta%4 bas ever: . girdac! of Te, wt © furew Bysliro sr oo. fiw at Gedeti ee a ee eo aetts a T8748 tar sus% mre or SGeEse iam 3 “(459014 gk Qa apis effan. 52, : oa ‘liv eots olAt - : Lio4ed * us sees oa? + a teed tebint? oad aul det mse on * eae ie o¢-t-baT [a7 Z auc , ih aio va y rs avet oes * cy iawei 4 ,eovi: ater te ett ai tee -pelem-> S i745. wevi- ruts guano iot otf B Pon af eters gud: hiv 1, paltige: boo; eryoes _- elosts ave fu? wedi 2.205 oy 2t ovat aeta ‘ eisnT at pebiesd oi. ee wei) uni nf wadete OD doide 32 mm Bwreqo sfvt< ‘to Pon: mo ste at »tidsavie q. ,Sasinid 62!- ogre | st wytqg. ton saan Sivivoes aaaser: atfe VSiaiuc ova vo to - q 110 #078 ge “a tc off nt "qn tariane ‘eq Jege nD a aay Peel ot 2ffera ‘,fedend teq taae 8 t feet Ger nt otiatt @-evioret ovle * aio oot eh ease Incusan eat 7 . gafs guibyfont jetod bat=* ange @rad dotfvo fa ferotd .gatca aty,29255_ een aout to. oats etorn ivan? c#lalesteq wep efor rotsalg - ri entijee tai2vo to exeksevie!eds svisnaiat _ mort no Boirxco nad svad ageing smtivot To Yo sbhjoset yOlsew Ans pha in enw Mets? reed eyed etugateq@mes fio ysl sloviane nota YS eats os eefuTonas yitsten To-“thers ict Baa pg Tod Yad ornodasetO afd To exetaw bats “ot eyateea soloed auw GOL tosy oft ft Bees Ith tents nt. ‘bas eenad Jeo at ant 7 at + srastyeda bao? aidetisvl; Men wotel yrev. _ i aL ie. ped #A . tee to: tas Mgaltiera nt WHOL voted caw See Vie fF: Meat on? , FOCI SALCyo tO uly wert? sea - so OW etout srice. s of oea te. dere outs LAVeD ay aE meT266 Won ect ao onicveingag ems yy tlio’ ef alged wie ny g004( onftelinuey ads) weeIo! rt? MITC ee I "apgiay 2sore eee Ste a> ‘te Via rs TOL yod Stencils cox JE ate tted-« botiezcs =5 lt “Foval fe! scams OU wees Eity. vais tant: efacdh fav pin 7) Th apatannd Denied telay colssulany to | ON THE CULTURE OF OYSTER LARVAZ IN THE LABORATORY - =) dD ne Harry C, Davis, Aquatic Biologist Fish and Wildlife Service, Milford, Connecticut, OK 2K ok ok In a study of the effects of the various conditions which the oyster larvae may encounter in nature, it is desirable to be able to maintain cultures of the larvae in the laboratory during as many months of the years as possible, Observations on these cultures will undoubt- edly reveal many of the conditions responsible for the death of larvae in nature and may finally explain why the oyster set is a complete failure in certain locali- ties in some years, Using methods developed at Milford Laboratory for inducing gonad development out of season, it is now ~- possible to obtain larvae almost throughout the year, During the last year larvae have been reared to the setting stage not only in summer but also in winter get- ting sets as high as several hundred spat per 16 liter (approximately 4.2 gallon) culture jar at either season. The standard method for rearing oyster larvae has previously been described in detail. Briefly, it con- Sists of changing the sea water in the culture jars, every second day, through stainless steel screens that retain the larvae, The cultures are constantly aerated and supplementary food is added daily. Our experience indicates that this offers the larvae the best condi- tions attainable, at the present time, in the labora- tory. When more frequent changes have been made, ex-~ cept in rare instances, no improvement has been noted either in rate of growth or in survival of the larvae, They do not do as well if changed less frequently how~ ever, probably an accumulation of waste products causes the slower rate of growth and poorer survival of larvae noted in these cases, In using the methods for inducing gonad development out of season and rearing larvae in the laboratory ab- normal larvae were occasionally encountered, Some of these abnormal larvae were apparently due to immature eggs, obtained by induced abortive spawnings of females that were not fully ripe. In some cases such spawnings appeared to be quite normal and large quantities of eggs were released, more frequently, however, comparatively few eggs were released. If, for example, oysters were spawned after relatively short conditioning pericds at temperatures only slightly above 20,0°C,, the eggs some~ times developed only to the late gastrula or early tro. Chophore stages, At these stages they became so "sticky" that they adhered to each other and to the walls of the culture jar, particularly at the water line where they normally congregate in large numbers, After 24 hours in such a culture, a gummy ring was found at the water line and all the larvae were dead, With somewhat more advanced but still immature eggs, the larvae developed (Sey, Cal lait “etd ult 7 it ® « iiaa ¢ ‘ a i é "=e 'T)4 - Cc Ft i ded 4 J 4 ale Tat cL ie V © » VT St ‘ a . * 75) i Rin? mele - Wa ay) i a 9 } ; } é | : , a } a! ‘ } J _ Vv" e j ~ U — SkI bree ott? . i” " cit * ' sed f j j ii 4 aGy re! J ‘3 } ® - ——s | Y 4 + ( slds setrech en , - . _ acd . _ * ' a aseey et? tos oe qetaity wich: xk added mo LEI ens) 2 i: ing-m eholdavivedd) ,«fdtseca 2 ‘ , - . » “ pia * e CF ose mot obi deren wv ARID is iG ort J LDS “wil GERleee VY riadi* «¢ Sire - Stud oi. 4k oe TS otasa — oa : = ~~. TT ae » eer ' 2 Bod ° IG ‘ ; 4) ? ad _ ' a ® es 7 a bed \y i ’ Tl tatave oi a WF ; f (fra rs rs y rn r 4 vitoa twa? miles ane rt , =n jc “tere Boge 7n2 fet. i es} YIO > . Sree ww @8 se niet om ty «(CYS 4 e% TI 700. lee 4 : ) 1B Sohorg oteqw le ana? - ‘a vial % favivive 660g Bee Plots ‘to fut te +S g Se) 4 exqofeveb haniog antoubat mat eiertged ad? ante at % wtodatoda! odt pt savin gnitept Gas mmecee. to Ju0 omoc . Sere tiioons = sofenaos @i~w os ial Lawton bf ned os aub v fir ote sts Ocew CnvTal Lorton: ead? m2 Ww sarclowey< ety ro¢e beouvit wi Sealetds 3399 ai mwage come teens empe nt) = .rtt etEUt-don otew Gadd. ® to Seto tiseup agtsl Saa Loans eebsip oo) ng ic ote yp 7 vivetamos ,Tevevo ;vicnovert?t ee ,foresiat emsv ,. - Ww Stota YO s evn =) 163, s Td, may: wi! 4 rng ; Bane wot - 2, asoires BMLMOrs tbe o Prous viovesales eset: Innwaga © OF. Rage oi? .4270,0S avoda bet ah Ae yim sents ] t +30 tb hires saa otal ery 6s vine ‘feqolevah: oe cowoad va? esgnse akeit? th hOgsvt. 07 So efieu ers af Des tedte doa oF fete ond axed ontl seocv edt ss rhunlvoge 10%, wot 4 -aeo%k Lareteun egtet at eo age Btu m8 wag bag ad? ga tym? tew an er mou atau ,f shells more or less normally but were quite small measuring only 60 to 70%at the 48-hour straight hinge stage, A situation, which may have a similar explan- tion, was encountered with oysters from the natural beds in Milford Harbor and Long Island Sound in the summer of 1948, During the period of July 5-15 five groups of oysters from these beds were spawned with none of the five batches of spawn collected giving more than few very small straight hinge larvae, even though on July 1st and end similar groups of oysters had been brought into the laboratory ad spawned and the resulting larvae developed normally. Also on July 19 some of the oysters of the July 15 group spawned again and these larvae developed normally, Probably most of the oysters involved had spawned on the natural beds just prior to being brought in and possibly at the time of their first Spawning in the laboratory had not again accumula=- ted fully mature eggs, Overcrowding the larvae in the culture jars may also result in abnormal larvae, In most cul- tures that contained 500 or more eggs per cubic centimeter, if the larvae developed to the shelled stages at all, the shells formed were abnormal and the larvae soon died. In some cases, hcwever, using daily changes of water and the addition of large quantities of supplemental food, such cultures have been carried for 15 days and more, and the larvae have shown some growth, Another possible cause of abnormal larvae is the use of sea water in which adult oysters have been kept, Eggs collected from the conditioning tanks and trays after a mass spawning usually gave a poor percentage of shelled larvae many of which were abnormal in shape. Fewer abnormal larvae are obtained when large numbers of eggs are spawned in a small vessel so that the sea water containing the eggs can be greatly diluted with fresh sea water in preparing the cultures, Parallel cultures, one of which was diluted with fresh sea water, while the other was diluted with water from an aquarium in which adult oysters were being conditioned, showed that the sea water in which adult oysters had been kept gave a much lower percentage of shelled larvae and many of them were abnormal in shape, Regardless of the cause of the abnormality, such larvae rarely grow satisfactorily, even though the conditions causing it are later corrected and the larvae may live for several days, Healthy larvae, however, appear to be quite hardy and capable of withstanding many of the teme= porary changes in the physical conditions they are (-34~) ain 5 - t £a8)..%9 2 TOSI allots a fax . ri &.! ; at oy ¢ g ' h baad aniftiuesow seygere oyekrt Ip iii "FJ : 9 . Catt ail ' arg : ans ‘ MA > ' j shot = \ane cr, ig i lupe ‘ av? ove om evi $799 2 5 ay] mst T ILW grit fans {Is9 we is | 4 eB ber ona fel Th ‘ r te ; —_. rae sos . tay ont Fey lic f he = a Lf Van 4 vot suvital 3an83 Pt J Hag eu oc % veya o:t3 TO apie BiG oo eal ob onviash oteti Basa o a yeoty Ravictnt stetets G17 ty Seow ¢ie att ye j - TOL" , 74 z » fact Mf ak: o ape y if Pete? tis? Fo @erz-sn? te usc riayrd *h1SO Oe BSA StH Pail Ye 0 Al , £2 Sn Mie ; eh : S.A Fed etot ewriis. ofd of Ge7irt wt? sativoiste alo Jeon ot Arg . Teorond (weet oaffa vi . ald deg e936 21 ‘¢ 00C teqgiatnas Jat? 26a ‘betlede off of Laqoieveh oavial ott” ,totoutims -* fre Laictonga daa eitefin, oxi? © t@ tayate “pwevencd AAS Ghitid\¢ DelD Onoe seavtel ont : TO eo3-fPee vid : sf aso e330 “5 %9 ew ,2exstiine Jollee . seen: at? antis¢es tq ay iP ony effiv ,19dsy esa ies ailv fete ltd eew Aolidv wie clk wvltomyps mA moTt hs tw Modwf?d sew caida bewotle ,bencis}Arica anied atew ateleG Birbs sotdiv. feed Sef artovueve JLins beta #) ‘Fe gato 760 toJal bam GeVEL saviel stom) %%' ginor o> 08 witli lonos omdategnes fertntng ot: Dani? ; P%ote toi). ,ylowkEaw woce Sieow 0L 2 89. Fs a) Pyakraueso vuvntoueed nt enaiteuroult yaeetbro the tot Trwosde Esgerth Slivo esogew fotirica ene fee ton gSeyins jo WOT eri aida ans it yritioe yitavect 46 vbess Bist as ? Fader Oop bel waves! tel? tavepads bein? amo welweli, ort ,.0 80.95 of 3 5! Geet gictunee Sitgath welded DasiGditiy c/o ss 1ef Tada dnt ; y sce Gee? at Ofte eldnet+j.4 offs ass savtal Ete .fauley mots Meyforsht wot . | mee eid ac ele i mi Jab MSAL33q ehW ocvist - E Ogi) Joy , iolew c3a Yo Stiog | Or ee. onan vilieRt hes svila = i : eras Jit ie’ edt So temtnoe 7 , Os J everita ’ Pgiiities to svuel wWeea wyrat 6 -)o caifdone AT a arog reotee 2 teow Jaq oF Eettod oxte a iq ticed bas grils eo ed of yin WiBtw se Yo . ; ( @228 OF otcengeés yood-eta 4 dest gtevevod ,cormbivw eMpwhitno ef espat Jog ob t v sae o ' ; sTID TE nur be EAs vo Savialt pd Qo eavial ob ss shoot to Bteliav » ghiw ar eakleou etedeyo “alqatyi0 ont “xo rer SRBEY. «83 Staci ‘totost gnitvictl aay at ius Ch geet? / etodel nt tesel {4 ,saviel witeyo cm ve Rpg ee ae = 2s Tr a 2 mretesh wo td etud{uo IanoteggSo ce cyst ddiw oust=s antives oct? ov nog mead cod soviet eadeye of af ; rb ae 06 mad ow svat aso on’ nt , Biot (civemolqgim Zp0 “moS taiints robs s9in oF "aslo hradt ent Yo osviai Jeg . nosiiasiq bextm Istovae Io ¥ns ,238 vel ,anptvih fo 101 Hoot [sinegelyuque es Liew piiup msviez getuiiio | 4 © «hued “ovo ed? no ,enviel tsteyo Atiw stidw ,eavrel — ¢ $24) owsxte 5 jeg ct efde nosd ow evant yilsaoleero: otto, Joris geivestetct 2. 35. .estilvo neo ORRTA stolsolos ,setalle feats to senitiva ee ‘(iog ss asvix cad oben of ? a. bite ,caytsl aslo w swtsyo tentia Ag That clam larvae do utilize foods that the oyster larvae cannot has been demonstrated by mixed cultures of clam and oyster larvae in which their living condi- tions must be the same, Supplemental foods were used that permitted the clam larvae to grow normally and set in the regular 12 to 1-day period, The oyster larvae, however, grew very little or not at all, and eventually died, These results were not due to the clam larvae, which are larger, robbing the oyster larvae of food since the results were the same even when only a half dozen or so clam larvae were present in the mixture, Similar results were aiso obtained using parallel cultures of clam and oyster larvae that received the same food, The fact that cultures of clam larvae can re- gularly be reared to the setting stage, while many of our cultures of Eastern oyster larvae cannot ap- pear to be due solely to the ability of the clam larvae to utilize a much wider variety of supplemen-~ tal foods, Likewise, larvae of our Eastern oyster cannot utilize foods that larvae of the Olympia oyster can use, Cuitures of the Olympia larvae have been reared to the setting stage, while parallel cultures of our Long Island Sound larvae receiving the same food grew very slowly, with one culture all dead in 10 days, the second culture almost all dead at 15 days and the re- maining culture showing a very wide range of sizes, from 75A straight hinge larvae to medium umbo stages, by the time the Olympia larvae set, In laboratory cultures, at least, food seems to be the limiting factor in the growth of oyster larvae, While occasional cultures have been reared to the set-~ ting stage merely by changing the sea water every 48 hours, throughout most of the year supplemental feed- ing is necessary, Evidence that it is lack of food that limits the growth in our cultures of oyster larvae was obtained from parallel cultures one of which received supple- mental food while the other did not, Most of the cultures in which the larvae reached the setting stage were those that received supplemental food, and in most cases larvae in the parallel unfed cultures grew very little and eventually all died, In many cases, of course, both cultures grew very little and died in about 10 days, apparently becuase the supplemental foods used- in those cases were not utilizable by the oyster larvae, Another indication that it is lack of proper food that prevents many of our cultures of oyster larvae from growing is that it is possible to duplicate, with clam larvae, the slow rate of growth, wide variations in size and high mortality, so characteristic of many (~36~) > i is i = Jaye 90) Jedd aboot Pebay.a 56) be ‘vs me ars pan? teu Ivo Lowta'yd be otysnoosh- med 2 t ‘dommes oaviot «bndd) of byt tect cotdw ot és roel tdtove: Dan malo to be=L ete r uiool J iq on { ; b anol? Gre wile 0 7) i axed wort “bd 4 oO ari : Fr i ‘S M { oe : AAR iz i \ iv y> { Meth if Sra ? a o8 r geod? : yVv9 7 Th. oye 4f vf, ¢ tee tal arta) siol ; mato t29Q on to tives? 61) eonts ! x avril Jriete ta i's o eo Aesad Ine opr: Bont ; tow 22fvewr celibate f t eitd ih ? ary! j fire: woilo Lear est’ £ req ante Ly et eet : : ry triw .,w@pare I) Jee ore) GF jn mw po WETS 13 rs it reink “Ssicue Bosiand * Swiss nid id _EA« ) eto « fi ” Bk ano Stas CO oy.) «4 raf ; at satthiu - uk ow eve? vis! ctqa vsivo eau eae aoretbre Lelie 6 ila wines wis of % ear) 500? ef60 54! sal View o r, teh 4 al : 9a" asus - AS suet fhe exetina aro Mi lw , ghey le free . oot ONY Hyhans ants cl! ae t Ste Focal uTive Ragosa a? Acs 2o Ones. aor y * g g0are siutigs aninian - ,29g07F oda nothin a sevih! semis? JifsieaPey mort | W642 nsv%t meio of2 @ntt edt yd - a of espen hoot eee. 98 ,20 tet fuse eeetaxcodaL al j S ones at toveye Ta mysosg ar’ of unigigt piteimht wit ad - etee ont of Sers0% Gael 91 | | Bd Ctov) OTe pie eft egtor = =. vis tem. og aie: gait” | shoot Issrtons Lqqes Gay ae “vit es obi se won: ee Pe etseeeou 3t gat fet : Lie : edt adtalt ‘gst. Boot Wo Moet of 12 vows sonebtve Beatetdo saw pavial 737eW0. to. amiss tuo-nt Awotg, “ ~eiiqye. beviaset dolay Fe sin) hy ad Lira Kolfa'ts mort =~, ed? to 2264 Tom DES mais sip wt Ldwboct facimea ggnt2 yiketoe arty borane? awe i datriv gk aetus ive. - Spon al fis (boot Letosmefqane . Eearecs - fede pantie ‘9190 Pa Wats e511) tuo fain fait acag ae t4 on ; to ,2euso yoam cl .Sshh [fa ei iavnawe- ‘Suede ab bolb bre olttil vmy very bare lae “Beau eboot Lasse no Cepia, ait evshses. Ul dost aavial Yoteva sis. vd sidant fide. ia Siow BeR50 i oi ue a pl hao. Tago ty fte lon ot +L Fs i watdnol Ort vradtagh «° 1. @avital watayo ito pau: fu TS: oe. Eg dehy (efsoklqus oF ofdtescq st beh 8 tagkt aba abv. ,diworg buses t tisha RO oiterrovoszeno ny 7 \% i of the cultures of oyster larvae, merely by supply- ing insufficient quantities or the wrong type of food to the clam larvae, Finally, it is difficult to conceive any other factor than lack of proper food that would so pro- long the free-swimming period of our Eastern oyster larvae while by using the same techniques hard clam larvae and Olympia oyster larvae are regularly rear~ ed to the setting stage in relatively normal time. Although in one experiment our Bastern oyster larvae were reared to the setting stage in 23 days, in most cases it required 36 to 40 days for the larvae to reach the setting stage, and in a culture from eggs spawned January 6 it required 50 days for the first larva to reach the setting stage, the most profuse setting was between the 52nd and 5Suth days and some setting continued until the 60th day. Two conclusions, therefore, seem warranted - first, that our Eastern oyster larvae are not able to utilize as wide a variety of foods as can the larvae of the hard clam or the Olympia oyster, and second, that it is food, at least in laboratory cultures, that is the limiting factor in growth of oyster larvae, Preliminary experiments are in progress to ex- plore the possibilities of interspecific hybridiza*ion, On several occasions active Olympia sperm have bern added to unfertilized eggs of our Long Island Sound oysters but fertilization did not occur, Such eggs held for as long as eight hours showed no evidence of fertilization. In some instances active sperm from our Eastern oysters were added two or more hours after the addition of the Olympia sperm and in such cases fertilization by the Eastern oyster sperm and the sub~ sequent development of the eggs was equally as good as for unfertilized control eggs held for similar periods before the addition of Eastern sperm, The Olympia sperm, therefore, probably does not even enter the ege of our Long Island Sound oyster since it does not cause the formation of a fertilization membrane nor does it interfere in any way with the fertilization by Eastern oyster sperm, Although crosses have been made between the Eastern oyster and the Japanese oyster, Ostrea gigas, and between the Eastern oyster and the Kumamoto oyster (probably a variety of 0. gigas) and reciprocal fer- tilization is obtained, no conclusions can be drawn as to the viability of the resulting larvae, The adult Japanese and Kumamoto oysters were shipped to us from the State of Washington in the fall and apparently had not spawned in the Washington waters last summer since all were found to contain large quantities of spawn. Although some of these oysters were induced to spawn and their eggs and sperm used in the crosses, we are in some doubt that such spawn was normal, Hence, in (-37-) “ease Vi yfoves ,sevtel ieteyp to sated ios. orld to O 81t? gcorw Gil? Yo-eelitineup Jaoholsioant. gat : SVIOL Bold gif DI boot medio yin ayiesioo of thiottthp ak IF eitect’, ~oud oa filbow Fea? hoot toqgote ‘Ya Masel god? 149481 Teseyo Widens 2 To botieg gkiagiie-oe2? oc? gral malo beat Baiiplates? ote of? onda. 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OFF TSIge Fave Toy so0b ete we? -otqs on eook $i éonle teteyo Sargh: senl aie 2 3ge 20n epnidiied nolseztiiow? « Weueolterwt ec? wate moiszast(tsrs? edd d3iv taw (ne Bt et lteter ft woohb ; atege Taheyo itetenl yd | ed? reetiod ehaon nesd svad eseso1 muodt mh | +30 sotavo Bdonttel edt Ban yaleqo costae Be Caamit godt bas sotayo wretes® of? epowied fas —tet. leooigioet fre (azghy .o Io yoeltav a eidedong? fitwath ed me troleufoao> 04 ,benterde ef notisstl Siubs et? .opvieal upisiscat odd 26 Wlitdate ad? of Ort ay of heqgicds otow atetryo ofomemud Sno ofsnegel ul Ulsre toys {fer od? ct no? esW Yo staté wis Younus Jeol stotew wotyatdesi of? at benws wiways Ya sefehinanup egtaf niategs oF? brood Away? of kaquint grew evetwys Jo oooe Ff at? ow ,eentoto ors at boop erege One tage at {fA KAUS Ps h ) > pavtat mtoyo ntaido a? eiikean) tix ak 21 = tmpy st. to 2200 Saotguoti) ,yroietodsl sds of = >= ged ogets ynitiee arif od eamiel ws ts OF bus > a etammve mi fyts totoiw or : : j ebray eting 32 segrTat “id Last Pee i IGk® nt : >. © Of omens ytewqees Jess! Ts fretutiiv aso bas : fees ml , : ant @ at 9s tiga -rteninilies4 = Aa Sah eel ae piso a Vy seeiseqrusiak to eats oct o> « Hihe stgts Jon it ont tetego atqmyld a) ae poh ; Tal’. Say ere oretasd sit => ‘ . i lg ,taveyo Tretead oes ; » “easel esas mov? osvisl ae 4), ¢ é- babu lone Ma arr @ SB aw - ‘ Lee s. THE OYSTER INDUSTRY OF NORTH CAROLINA AND SOME OF ITS PROBLEMS, A, F, Chestnut, Institute of Fisheries Research, Morehead City, N.C. sek ak seo According to the available statistics, North Carolina has maintained a rather modest position in oyster production over the past fifty years, In 1940, for example, it was third or fourth from the bottom of the list of oyster-producing states along the Atlantic and Guif coasts, Since 1930 production has only twice exceeded 500,000 bushels in a single season, At least four surveys have been made of North Carolina waters concerning the possibilities of oyster culture (Win- slow, 1886; Grave, 1904; Coker, 1907; Galtsoff and Seiwell, 1928), Each survey appears to express the opinion that potentialities exist for a great industry. However, the industry has been slow to develop, and the oyster continues to represent one of the great undeveloped natural resources of the state, The oyster-producing areas are located in the numerous sounds of the state, bound on the ocean side by the so-called "banks", making these sounds almost landlocked bodies of water, Albemarle and Currituck Sounds are considered too fresh for oysters, Oysters are found growing from Roanoke Island to the South Carolina border, Pamlico Sound produces the bulk of the oysters marketed in the state, This is not surprising when we consider that this body of water with approximately 1, 100,000 acres is seven times greater than Roanoke, Croatan, Bogue and Core Sounds combined, Pamlico Sound, some seventy miles long by thirty miles wide at its greatest length and breadth, is a relatively shallow body of water aver- aging 18 feet in depth, with the greatest depth at 25 feet, Several shoals extend from the mainland into the sound. Brant Island Shoal with a depth of 2 to 8 feet extends in a northwest-southeast direction about half way across the sound, Bluff Shoal ex- tends in a north-south direction from the northern shore of Pamlico Sound with a depth of 7 to Jl feet overlying the shoal, It merges into Royal Shoal which extends to Ocracoke Inlet, The bottom of Pamlico Sound varies from mud to hard sand with the mud bot- tom confined chiefly to the channels of the various tributaries, The salinity in the immediate vicinity of the inlets averages about 30 parts per thousand, progressively diminishing toward the mouths of the Pamlico and Neuse Rivers on the western side of.the sound, The currents are determined largely by the winds, and the tidal fluctuations are found in the vicinity of the inlets, 39-) | ep Vien : re wae LY mea TAOS A AMLIONN WOU NO Yerecaet ayreyy dum mg mietendi Aare ; L6G Sse 1 : inte et) .t5,4 ¢ ’ 4 ° ' i i OF] ints iq? ; 373 ) hh VIL. See et ¥ + oe | 7 _ MGon ,Soisetlots eldaliove efF BF gakbto xo! mt morele O@ Prohoau tarnifct a Decrete hen wid onilotwso iver. ni "et e" 43 oi Lr rs ™ oly 2) +. bes es) oTd "A pe 4 *) ® mood arft' 4 to Oris? gee 7 , eta9 To? ei nes cos age yitoubon sees + if ons £6 soit ache veces Gocie gurtaoe 120 rus 2B 8262 o{snt sIniindd O99 057 Stetev exntilot:) dftrol 2. Len mos. ovat ivs . Sivoo. wesl2yo To ahthitdienoy dl? gaticagues mwesgisd -VoCOL ,s 55 FOC! Bur sony jeote } 2treges wwe dont 0s t . fleuteé a's = e L Lot — ive. BS8siialinsassca 2047 solnige yee ot wtz med eeu! reraven! >i? » tavewoll eae a wi? ‘lo one Tmsasqa't of eopnticw:.telaya ont " ooare at? Rd eeo*u0" nt Texdder betolevaliuan ‘ame 6 5¢4 | ada ahetas ae Se bn 47 on Dewod ,siése oe mn? 36 a5 uve cue waUs Suuos seed? pjiter ("ore bal: es of!) wa shies a eltaxed i De ya a rifor Setgetine! trpdle = set ‘eat O07 beweAdarion Hoa suo hive . A? aa ate} @tombot my 27 ehteory, Tt 4 wteyo aubete re Oe SoLigg. = ... 2 “cod: fiex. finos | estes ans Gi teéeigec » yo2- Wd “oo: tied ta yoo” atts teat me Od. WN cook: mat) yiue Jor aves BE Wason OGL (2 elena tet iva aiiv wav | ea tte Suged wlintieriiacadomtsn 2 Sadeosg amis; Refit YJnawe2 smc wou este" wee vont - ) Mignel sss7e0 a Att 2 ate eatin Rees 7 in salow wy hed ws ‘o > thadsrg : MGaeb teofesty a7 ae" mixes at sat AL 4 » Shaintag sdf acott ee 3 Gade f pte Bhed fact etolwared_qatci2 pore tertevs eta 6ito : |, S2%h Dryet Gotfmst tener wal ad? Ad betsoo un ate ceS te O0F Gl eee Site Se dooney cl. waveve A if eneoed. ooklors) iit to eetaube! «lay eT © -dethord teteyo: hoaws eg Moab nm? eaceddoiat td italicuine oft oF wpige® eaogeni) eG? at cots at-al . ,ooots Javanese af Ai 86'8200 Sodew “= t0om “onl? erld-da bonepeoty aGtoreyo ail? Jay 98m al To wy. Sy \ edxoojatono ae 7 bre ecoulsial ot feqgide otav See ee Jose9 Sa asaiae [ftdy alit : .2teteyo y =faoll ww Recqhaeas bea S5totq ,betouta ote wirolteyo ; mal 7 .utaleah ejisog @m08 obbsodh wat Poaq.ec? nivel | WS epeslrid odT |, Abin of at Egil | . Dna Soo hiess nievlad afeiak Jmpleey nawt " ed i ode tonthet Yloletqmes, bits etoini : a rs a 4 5 L ef wth analy atta Jhabaita worl ots . eer ne A idesoksen nt beowk ae ewe sietayo ero y at co bestent zoavod y auc mic. wan CE yr ) agecel aynely toLtear re: tlh Bikes rishi Te7eY0 ', £3 otey cect mscer rece trie ree beortiat & . «(rot battizres 69 czirw .efadaced? at sozued qableude YT BO ZUOL nts. Se nee qgide efate-tozat 7 meath ow? sste Soph onilu | mE Goteonl ots Mmaos" add. gite ti tae tacl betetego fats teint gvotued edt mort areteyo. ef “ * genq Shoe utly gotybesb sansiupet ene * eth EEC De meas cee Ap gite S602 Sf '%0 ean aaph0 a The legislature of 1947, upon the recommendation of a committee appointed by Governor Cherry, passed a law imposing a tax of 50¢ on every bushel of oys- ters going out of the state in the shell, Attempts to repeal this measure were defeated during the 1949 session. Opponents of the tax believe that North Carolina could be developed into an important seed-producing area and believe that such a tax is hindering this program, There are areas where an abundance of seed could be procured in Bogue, Core and Pamlico Sounds, A question arises whether the available seed be used within the state to maintain and encourage the industry or be allowed to leave the state, There may be sufficient for both pur- poses, ‘The legislature of 1947 also passed a regu- lation specifying the return of 50 percent of the shells accumulating at the shucking houses, thus inaugurating a definite shell-~planting program, A tax on oysters harvested from the natural beds was increased from 4+ to 8¢ per bushel, The in- creased revenue is to aid in meeting the expenses of shell plantings, In 1947, 63,258 bushels of shells were planted, In 1948, this amount was in- creased to 95,919 bushels, In 1949, 119,517 bushels of shells were planted as the state's quota with an additional 34,000 bushels of shell purchased, Ten thousand bushels of seed oysters were transplanted as an experimental procedure in three counties, The private leasing of grounds for oyster culture has been emphasized since the time of Winslow's survey in 1886. This supvosed solution to the problem of increased oyster preduction and development of the industry has not been too popu- lar, Leasing of bottom is permitted within the state with limits of 50 acres in the tributaries and 200 acres in Pamlico Sound, However, the counties of Hyde and Pamlico prohibit leasing of bottom, There are at present but 3,232 acres under lease, The majority of these grounds average ten acres and are used to raise oysters for family use or to supply oyster roasts, These leased areas are found chiefly in the tributaries of Core and Bogue Sounds, Many factors appear to favor North Carolina as an oyster-producing area, There is an abundance of seed in some areas, Potentialities exist in Core and Bogue Sounds for greater utilization and develop- ment of oyster seed, The quality of oysters is, in general, good and can compare favorably with oysters from other areas, The fact that North Carolina oys- ters have since 1890 been sold as Chesapeake oysters cannot be overlooked, North Carolina is situated about in the geographical center of the extreme ranges of the eastern oyster, Weather conditions favor rapid growth, making it possible, in some localities, to produce a marketable oyster in two years, The numbers of enemies are not as great as in other oyster~producing areas; Pamlico Sound is (-41-) ou 60) OI , tel to estate Gi tw otcia f hoe ofeh La! Setdanos a. 54 ate arod! .setvod 39139 CN? egeiD vs 76. °° “ftes4 ‘xo? ous cents Bodesl ee vit om e%00 To @e antl £1 .wovel ol Soto: Get le 00 @ AS of pil , & cfyo7) ,0O'\°O" robes Jeul ose tfLeurron -W-GR4i sald fost Liidnalsce xe Bas dseL yrew fb: Betnalqendts sfc YO clcserapeas svotsmwt 3 | oOB YW valores ecthet Shier TE os 605 mort obam Md Gd botaaldenstt yi o* vie. M24 boe® .GLeubtvib agek nt au 05 o-deégnes 2 mots & Git gnexuiat seqqu .. enw Tad mid céiiw GAUL “rer it.,mo 66 o¢ #b0L atk & hag bia ise hboatiod oo. to ditnet of ates ~lai Spa eet (fs bmo= “Atmag? of @iad Ins tettib eatdd toe of , RPUL Liug@A of ie 88 meTT eeesion! Ha Adin vLertot 8@ Uiee We Gigssi ef oten & .GR8i socRasyqec nt mm 98 w ofd nk. dypdel wi I2/ea! ALCL Wega se) i yo been gat inacl o=—PdGr pafrd {ell atpecTacelds af Ami’ .«o7lA JnexuJdet t8q @ 26 soliocios Intian 2 —) @itietoret mood fh livw oL$ih ie | . ; rradays 20 poat act 153 “toba) — Ba Arise earl Inala Mins to"? an jcerig to aaoltaevwt tendo ; Peinoniotivns. Yd Sane te! oh See Betoun eletel¥ora sito. | Bouvlave of oldiuaceil our ti phaal S si gi gat? sigh “Wale 7 biaat 2 abiawes mainte eyy warieini wis te Josette any) ednelaq a FO galiquer oun SASGowons!! “cores Pe avat _ “petiarart ocd sanasena) Ms “tte éldaveticnos even You a 926 od bbaed eaato newt Wo aioxe feria a todd opetnavbesté ATI ond paiwollot i 049% Hdaosa sit « he Pues nebl sit ome af bes Listes 46 ya? a2 no Gilad plrubhivrcenk dope edd Te eres fan divocy 2) 2.900% Sentws6e Se tod o 8 rate “ yadda a Ne bow (ie read naz boul $0 nist . niatte od tan yittleds al «9 pia Podenee! x. ettowreeds To. totam S. ,, igh ¢% “ile Ose a i090 afye Bais ao tses edd Aenteraay a ainss\o “Ss ba oty, .@: wTal. 20 paul ov bas diaeb * sabi ae watt aif 2 MAE Roo T= yal ont yntlisverd sod sth 4 eo: nee rivite Magione eL% mriedt00g) .~ narton TOQKY! a ° a ] cs hs ee Samus areal f ; ond “is Dee ievivus said ‘bana ‘ pacts Detrodes: iia 36 cowiel giol’ gviden gt? a , } Torrey bs) sie fed woh alwonoa wots Joo Boal Pa “Tei i eke ( af wigan THEW) igavisan Re fis ots eo vigtt Jorndati tin vost? of Scemtiatas at wet .anenuog a * Wa BIESIOD ol BE faye fou 19. “tod Jone } to own Eaviviwa don Aragey Stet? pntiovast » afdntts abe hp 10" ed on aso evoldav 2O%2 #teteyoO 10 6 a Owe 7 pertoLet : a: “ smemnotivas oilea and VIS ei as. Yobec’s pene Ba: ~% ib anol Ievseade vives wild «teideot bgt > Ma \ * be ‘waco es Resosque od ag diwots bas Sout bo. emooed taum wrstavo did dotdw of ; pei 4 t8¥G baredudypey aga. Stoalinonten Kf 02 oA mages eye nh Widtte pivode”ae¢ sdatsoavt aottednotowrat 4 natadas 9 9 i» value of the results of such observations lies in the desig- nation of those seed sources from which oysters do best when. transplanted to typical Maryland conditions, If seed from certain areas should show superior growth and survival char- acteristics then effort can be made to establish them as brook stock in the state seed producing areas. All oysters in these experiments have been grown on trays of the Sea Rac type placed on the bottom under the Laboratory pier in the Patuxent River, Depth of water over the trays is about four feet, the trays being placed side by side in a line extending at right angles to the shore and with a com- paratively weak tidal current flowing across them. All oys- ters were placed by hand at a slight angle leaning on the left valve with the bills up. This position insures a uni- form exposure but seems to have produced a somewhat more elongate oyster than those grown flat down on the left valve. Tidal amplitude averages 1.2 feet and salinity approximately 14°/00 varying from a normal of about 11 in late spring to 16.5 in the fall. Considerable variations from normal may occur from year to year. The initial plantings consisted of groups of 500 oysters Givided between two trays. Later plantings have employed somewhat smaller numbers. Each tray had 2 x 4 timbers wired to its bottom to prevent settling. These timbers were aban- doned after the first year since it was found that they were destroyed by shipworms in one season and no apparent differ- ence resulted from resting the trays directly on the bottom, Measurements of the length and width of each oyster were made, usually at bi-monthly intervals. Depth was not meas- ured because the difficulty encountered with fouling organ- isms and erosion of the shell made it impractical to attain sufficient accuracy where so many animals are measured, Boxes were measured and a correction for their size was ap- plied to the preceding measurement since it was observed that typically those which died had made little or no recent growth, Occasionally a few individuals disappeared from the trays and could not be accounted for. The series under ob- servation was added to in 1948 and again in 1949. Similar plantings have been started in a prong of the Maryland por- tion of Chincoteague Bay. Growth and mortality curves for the various groups have been plotted. The patterns of growth at Solomons dur- ing 1947, 1948 and the spring of 1949 have been somewhat different. Growth during the spring of 1947 was good but levelled off with little or no growth occurring during July and August. Rapid fall growth followed. The interval be~ tween late fall and early spring measurements was too great to show any cessation of growth during the winter months. Growth during the spring of 19438 was again rapid and of an (-45~) ener iced ads od ost analéavivode fave To sltvass eit Yost == ° iw teed of a1asaXe dotie wort adonion Beye syott Jo nobiad © yy” not? Boca tl .aaniiiGgoo buaicral Iaeicry? .o9 Lataalganety i ado Levivwoe bia neig Olreque wots Biicda aqeta neste Gee mots Asliddees G2 lnm wi beg Pw Te ness editvsiaetoa, ~ : there anicvodig Skee ofe29 ane os Booka Hoot © ° ay a —— - - . j no nwote evet. sigmetioqxs chat@ ath, etelaye TA i Seticdmt afl moj Jed a4) 26 Bedale wh ee add. ‘lo nests ald “tedae To digs’ ~,740iA je eda “nt seta end ob “eBts Bectl piled wien GAS poset wet juoda - : : ‘ ® a ¥ ! ea] mage erota ei of eéisva S660 da prtidsdee antl RAR, Ged! 4y0'tsa pilwolt devia Aaen Yfevisetag ‘eae Seleatnads ofsna Tabla a 4h Diet GP Beneia eres wrss : Selaewmenl votsiveg atcT av nLEtt wie ivewy wvlavy ITAL : iB @iwenoe © baduheta avai od ess weeoges mtor ini wif do vob Jatt wom, sues (old Sefayo oouaaots 3 pings Widllew bea. 72601 2.1 equine Weeds Japlt P Rigas ofa al Ll guecda Yo tarmt ou) qisyray CON bt iteaon mort sioldatss? eldereiiimes \F ane wt OBL = “ae OF TR Gets 400 Pad Oh2 tornado Io dolaiunao eyyPoidlg bar tint adT Bovslawe avad eyitinaly edad. wyvee ANt Saew od badtvts itw eroded) + x 5. Sel eV Sateen Tel lean Jeiwenca we ec Mar a Jeeta oS aottod #28 a2 a qi gaw ft “Oe@ fatli sic ToIte Kened # OD SG8 G4nGs Oho ti arivwatcs ud leq teeed piere Hihiw Gee Hiarel ef? Ie efreme teal

< *negilli- cafe Sout? GI af CometeIt1> Sechiat wren odd pili Grin heats sa or4uey Lis) i2ela07%3 eit? Jat? 7 <0 Boek eit. Gre 206) Wo Neve tp. carers toog Utev edd yitwom (pine al squvesa ban id Manel eaAteYA .getsqe atid Niwot to - = : Pialel yet ol Piso Yi wevdy Jats 59 tuiinite aiiup . wos f ia % ote | = foe RS Lancenoe Bie Merauuieaioge Jans ose tdawllt ©” ) asde goetad a5sc0% dase = Gt Gawot Jostta yan peonetes 7 ai f patwors aprowe srerweVUAb els neowied dnetaqqa ah i grain ist 9 ok WPeT We adtyial ad? ,anomolg® fe aed , Meat ape t*% oe mute @2 -@nitnaia boxe sable fa nt Saw yt sunset oonldd _ 1 a Sr Wess, novia ets tovlA dnox hal ; 2 tf BISat os os >on “cies tien samy Hotes vt HIDES | A “yp 26202 ee (et eesns pend ‘al Jrnectmod emwoe. | ae Ge! apt v1)" Ye? punto Vesey, Se | oh cant adlewe. xO | “toVER 90 7 ae my pe a Yes 8s at et at fe : oe a a a tee 6e sa, So OS ee av wo ve LENGTH IN MM. OF RANDOM SAMPLES OF PATUXENT PLANTING Seed from shell Year class April July Dec. July Oct. plants in '44 '44 '44 '45 '45 St. Mary's River 1943 27 43 Wa, 74 85 (marketed in 3rd year) Tables 2 and 3 show the growth of all groups started on trays in 1947 and 1948 as indicated by the product of length and width for one year periods, The cumulative per cent of mortality observed is also given. It will be noted that the mortality of established oysters during the second year is less than during the initial year. Higher mortality generally occurred among oysters transplanted from waters of greater salinity and among those of the smaller sizes, The best survival at Solomons, 5% mortality, has been among Gull Rock, N. ©., seed, which were of comparatively large size and from water subject to periods of fairly low sal~ inity. The greatest mortality, 58.4% was among the Long Island Sound Oysters from waters of a comparatively high and stable salinity. The seed transplanted from Chesa- peake salinities of around 12 to a portion of Chincoteague Bay, where salinities range from 20to 50 have shown better survival and growth than any of those planted at Solomons. - TABLE 2 GROWTH AND MORTALITY OF SEED OYSTERS PLANTED AT SOLOMONS IW MAY, 1947; SIZE EXPRESSED AS MM. LENGTH X MM, WIDTH Source of Seed Initial Size in % Mort. Size in % Mort. pizev Jityear beyear Ogf years 2 years Gull Rock, N. C. 2993 5047 2.8 5450 ao) Mullica River,N. J. 2846 4289 750 4442 1256 Milford, Conn. 2745 4599 40.8 4701 58.4 St. Mary's River, Mad. 2623 ASe7 eee oles 5256 26.2 James River, Va. 2094 4250 9.8 4410 13.4 Delaware River, N.J. 2094 5625 14.0 5982 25.2 Maurice River, N. J. 1649 SCIEN eLE .4 3484 20.4 Holland Straits, Md. 1584 3725 8.2 4901 1520 Eastern Bay, lid. 1348 34190 15.4 4339 1764 (=47—) BUSHMAS. MOOMAR: 0 gti 1 sempre =I 4 - OU MAIS TURXUTAT WW (>) J eal 380 vib jet retits tiaah eaata ‘uneY feds nore best a ae i ah) @ a > “at a tnell a * ts 98.) GORE, mental a'vmas del 7 1 ie ; 7 Arma cbt wt ey 9xrtnal) | | | a — berate ogi, to adwory nia wade E Bde S seid? — 4 | _ J bisiohont Oe GeOL bas Teel ak py sent nO) .BHOR Sq 388% aaQ w don digosl -isvig, cals af Sevteado” on, to ones t Ray pee re to Yiliadiom ats Sorts parm grad 2 aoa as t68t “a : ' = ‘gaion: — qxsz We mM ata Wrwom waht aes gd oe = fa GFTIsit wuz Bt 2a Gseesanixa Wits Si wt eal® .ytol & at esd fatsinl besa to sotuee tyne f aes £ este 3,2 {208 2008 0 Me nOORn Lied on" Ot Gace soce@ -.& savisvth soltinud a) Ob 18g2 bets eso, Gro TLL - oe | 9.03 ‘sts voce? .b ptevell ahetall. te p. ot : g,% ObGr ee eV .tevlk asmiat 2.28 S806 rr EHS foe U.K. towel avtaws 04 ». OS whee . 15% “EBT .G .W tev) cofusit aL Looe Fe £RS beat .pM ,adhent® baallo hy ' Och> . Olee abc bu ,yoa avedaas (—ta~)} TABLE 3 GROWTH AND MORTALITY OF SEED OYSTERS PLANTED AT SOLOMONS IN APRIL-MAY, 1948 Source of Seed Initial Size in % Mortality Size 1 year 1 year New Haven, Conn. 56735 4095 27.16 Hdveto River, ‘on. Cr. 2954 5566 14.9 Green Point, L, I. 2854 5575 57.0 New River, WN, C. 2047 2860 Sot Beautort, N. ¢. 1906 2522 22.0 Delaware River, NW. J. T2US 1687 41.6 Eastern Bay, Mad. 431 1678 48.6 Seed planted in Chincoteague Bay Harris Creek, lid. 4054 8505 5.0 Fishing Bay, lid. 5885 8646 2.8 Duration of the experiment has been too brief to fur- nish conclusive evidence as to whether or not significant aifferences in growth exist among the groups of surviving oysters after adjustment has been made to the environmental conditions prevailing at Solomons. That initial differences in growth and mortality are evident has been pointed out. Seed from the local state seed areas and that from Gull Rock, have thus far proven superior for planting under local conditions. However, differences in growth among individuals within a group have been observed to be much greater than those among the group averages. A greater or less number of runts which have made little noticeable growth during the period of measurements has been present in all groups. The two plantings in Chincoteague Bay shown in Table 3 present an interesting feature in that the Harris Creek seed are native to water which is typically clear and seldom roiled by wave action while the Fishing Bay seed are from a shallow water area frequently roiled by wave action ren— dering the water rather turbid and silt laden. The latter condition of the water is very pronounced over the soft textured shoals of Chincoteague Bay. Although both groups have made very rapid growth, the ones native to turbid water have done somewhat better in both growth and survival. These observations in general offer some indication that oysters which have grown for many generations in a given en= vironment may thrive somewhat better in that or a similar environment than will stock transplanted from areas where different conditions prevail. This does not preclude the (4a) 7 ; ‘o) down &@ ee - wary wv : aa ’ : | Ml . asateyo die % cen GHA HIWORD. j | BERL Lt EAA ML BOSD ING. TA CATAIE 7 ac vital Ron sal | tet dink "geod "to eonmog Yi PSs HOE oe nae L ale * ws 890s AMT Hand fees wall ~~ BE B steely Mee 5 « 0 cB awl ogated 1 =" QO. ava dTBS. Lid yintot need ™ 9. O88S Teo8. 60.4.9 tov lAl weit Poise. “sses Boek | 19 4M gttotesd ‘O.0e | Toot BIss ov alb gtOCdh otewated piel Ofer . feb shal gyo? oristada Wwe susessoorm£iny al bulhala beet it oe . cOSe anve Di~anet- ofdtal ane a8 6088, BAER DM. yal setdast = ; i 7 ie a) Tolad cor mise ya Raniectig-om olf Ao neldawG -- | Dr “Saaoltingts Jon 16 aeeiety a2 ao sianhive evieyfonos tata : “oabeterwe to INO) 402 erccm baht givers, ak apbootet teh miotivie at) S0 eben deed anil fwonreutha te) ta, a Tetaee : ystt(h Faldtak dnc? ~.«reorsick te put everg snogsibnos 7 OR gdue Beiniog b¥ed sat tachlys wie Yetierros Ban déwore nk | ffo0 wort fodd bas sawts Seen Oletq Loocl oft mott feed |, aah gilsoetg Vol tmtvsqua aeveiy tat aust avad ooh Pac { GMA ECON RE SomUNNTTLA yeAeNCH .anotzibnog > * =) SHODPADLTaqvNy MAID? 2 = | : ji . Se iv ; fsi® .6 gate Pes : ; ~ tefgelolé doyaoaalowiedetd “) P ative var eolvis8 atti prew _—* 2 50: | ear font ¥¢ Dow baci tun sheen tabs 08ve mall oft . | oped edd wi botoadiogs Soe #AdW eestmncd BOL sty to. 800 en ‘gbse1 dolde Soe 1 antent nan Selteilet™ enlist aetasa oLd —_ tawolfLot ; oe *OQoA. To sane Sra sdsceG ets yi bevoane th 2a") O© \:ase7p409 HE -soltemA to sefmi@ Borla’ sad Yo nevisadaen |) ed3 to colvis® eI IbliV one Balt sit , TART (bo ldnoage ve ~if ona Seglrodive Qerten el (ieitedn! ads Io saomiuaqed fadese edaitgotgs déiw aol jewgses ni ,eNaiisbnw af Badoot ‘@Toe ‘ai? Yo pelhiida evianmiowgnes yestonsya stateisinl has © « Stine’ ,welo Lfode-bran ols bio yptreccin yt V mel Made he; }qo7q. »tnolotd sd? 0) 2onas0% GeLsoldion die yehisgsozem* >. dwe ».nwsls dete TW 10 yevE2ive Yo aboisem bas -(potiese2 | S — efeltqitqgs Onesmoso) off of ents wowt LLada ostvied . ‘» cagvationp enmlo LLode-biad “ttede Sia od @, : Ifede-)ton sfad tino of exit nay | SOFT CLAM INVESTIGATION: The State of Maine has great quantities of soft-shell clams and an intense commercial fishery. The principal problem of the State of Maine Sea and Shore Fisheries Com- mission is the management of this fishery so that it shall not become depleted. In places the digging can be greatly increased, in other places it must be curtailed if the in- dustry is to continue. FISH AND WILDLIFE SERVICE RESEARCH PROGRAM IN MALNE: Boothbay Harbor has been selected as headquarters for the Clam Investigation as laboratory facilities are avail- able there and also as it is about the center of the soft clam producing area. Three biologists are stationed there at the present time and two beys have been chosen for study to develop methods for management of the clam fishery. These two bays, Sagadahoe Bay and Robinhood Cove, are lo- cated at the south and north side, respectively, of George- town Island. Sagadahoe Bay is a wide, flat, sandy bay, facing the open ocean, Low tides expose an area of flats three-quarters of a mile long and half a mile wide. From six to twelve diggers work in this area during the Winter and twenty to twenty-five during the Summer. Robinhood Cove which opens at the north side of Georgetown Island is a long, narrow, deep bay with rather steep muddy banks. A relatively small area is exposed at low tide but the shore line is about seven miles long and clams are quite abundant. The same men dig in both Robinhood Cove and Sagadahoe Bay are sell their catch to one or two clam buy- ers. These buyers have kept daily records of the number of bushels each man has dug for the last three years. They will give us these records and will continue to keep them for us in the future which will enable us to determine catch per unit of effort, or bushels per man tide in both areas. Each bay will be handled as a separate management »roblem to determine the amount of clams which can be re- moved each year without depleting the stock. To determine this we must first learn how fast the clams grow and how many clams are now present in the bay. We must determine how many young clams are added each year by setting and how many die of natural causes, such as predators, silting, freezing, disease, or old age. We have to know how many small clams are killed by the commercial digging and how many eggs are produced by clams of different ages and sizes, Balancing all of these factors will tell us the amount of clams which can be removed safely each year. This figure (ol) LTADIG SVL Oa. - * os Naithedtoa toc aslflinavp vane eid ont ah. to ‘odedd att isqhonit 4iT; Ioetxe “WO Docund sonaboucs of Sagrado aid asiw berseqnos sd eo yitarot De doudnco $d ote onotdeaidenvnt asondT iM? itn Ootkelmand golsedal® Gade Aux 998 satell to saad ets te sulbuta dneiq Joligva@al @eivic? atlin(iv’ bas dott @843. botootisg mood svar shoddapaioi .osfdeng Cnomsasnee o2 bey ae eae) “loue ed _* ao ae prninilto.steJé i . iL: Seago. son Yo ifs Gotadagad. te Kozdude er aid of pokiiiba nt | #eetadal Laude tO gitwldeve fito vol Ddpdaidolt Sug yet Ital deh od Lite eolvael of! San gear’ od yYadevtnt al? od Viti tae e6086 santG@tet e289 3o 50: ie Ba rota Wedaatd 83 20 shodJen canals 6¢lesGai eet vats? to dosrte ,° uted - 7 anemia Te ca an-Age ont? teed yanelo’ bess nat a@?e , foes een: sh © : . MOREAU ANDI ck Bee HNA Ya’ ‘ rt @40eth wld Yo erage, GAT — | = eiibertaug agtondoanontt bru eakdaqnel walt | eutal © «) efédamoqeot ef baa fi Seeent dodde afadt ~. coltsslsesy erxcneth both av0t of WHT pavisoubwiqg senp sew doldw asoth ed! te Ging boeolo aad notiolloq tahith ef9 Ic Mabsoos Debiny oq et seuuionsgan al= “Sect nnewe adioti doftes Sua etoseea baa sect rf .SuolYsa of enaded eas noltelaed nas oe ovoid of Gaiisto ebatfeg saleyg T 3 a at ineta ivol ."tevene Jaddvaq s ges: ae: datos tot anglo & aul Lanéie mod ,potermet steylac to F. fitw vistas Jekotpmeog BORAARS & og 96 pelbtzdies of! neti paléivavt tl > _— ome Betis nt detdesot eafo ts col eco a 7 ar, t-faet the Ipswich, Parker and Plum Island Rivers, was once a center of clam production and still has great poten- tialities. Most of this area is free from pollution and lies within the Refuge where experimental plots are easily protected. An office has been established at Newburyport and three biologists are stationed there. Arrangements have also been made for cooperative studies with Harvard Univ- ersity in this area. The Newburyport Unit will establish experimental clam farms and determine their commercial practicability, Spawning and setting of the larvae will be followed to de- velop methods of obtaining seed clams. Growth rates and mortality of the young clams will be determined. The effects of predators and means for their control will be studied. In addition, investigations will be made to establish the reasons for the decline in abundance of clams. Past catch records from the town shellfish wardens and the dig- gers themselves will be obtained to determine if overdig- ging can account for the decrease or if it could be a periodic fluctuation as some believe. Observations of areas closed because of sewage pollution should yield some valuable information concerning changes in abundance where there is no commercial fishery. The Joppa Flats, at the mouth of the Merrimack River, are full of large clams but have no small ones. This may indicate that no setting has occurred during the last three years or that some unfavor- able condition has killec the smaller clams. Spawning and setting will be studied here during this Summer to deter~ mine if reproduction is normal. All of this work will be in close cooperation with the Woods Hole Oceanographic Institution project at Barnstable and the Shellfish Program of the Marine Fish- eries Division of the liassachusetts Department of Conser- vation. ; he MeL = 4 oone Row .stevih inaint mult pie asarel ,coiwaqt adf * snodoq Juste acd Liiva Uns actroutorm melo te seed — 7 ban nestuiio; morh sort ef sare Ny To Joo! ,s0ts fats ~~ fuse. 610 gfolq fesseulierxs sists esttai add Hiddiw estl” ~ a . ; ‘+Getous org a i. — ~ Zz — ; D ; | Die Jrorewideet 31 biel idesns noed gait noi TI0 ha svat sicomopnersh viens, banoiiasea ete aleisoletd setts <2 a byawiall fiziw saldvte svijisiteqoo9, Fok chew masa Osis : : ite stds nt Yilsets _ Poa a - —_ _ ‘ § Easaaminogve dsitdataé Uiiw siot(greggmeed! ont ~ eebbidestsoasy Ialvrsiaon het? gatesetet Sag gmt i Bewetio: sc Litw esyiel sit To palsy fn poiawade btu 4 lay divoD .edalo Fats, sian Jo_etcsitem aofey as ioresed' ad [fiw dioto aaow sig 14 '¥IfiaTion me in Pigisaoo. sds Sot_enien bee wroseeeis “io Bloutts | 7 t : 7 ; paths fesse oF sham od Litw Banisas 2. want ,mGgd LASe ude #2 stjicef mar wet anovaen ott a ove? Se) ORE Girtoost gras Spot silo ot See Gavlcaseds ateg 7 Rh. to qanse ue aay “at Zapooon nao pots oad0 ..eveltod sons -s pelyeysolt olbol ted ade goidufiog sapupe to snils0w ospolo saWia Regiels sniaryendes nolsemm int oldniley. Lado .wegawe? Saloremacy on of oiedt” oJ 14 ifiw nam ood Cr). ,meldotq - $id wondtat ,netaouberao sntan mort eanto deen printed ph fitw. suk F teqord ait.24 sovgw add af Deoatg gifece osats Ss <-f2tod theae wato doted Sv R20 wed duc. ,Jegs igzawo Mogae : _ felorammeo Saqofove> se inet baeg antoteddo, to aborvem — sow “losves Bagel oh -eiditanst ed. Ieven nae ontmist aslo _») Oaditta edt. Ste —ofaW cihd-nl govd Be soivfsat tedtt afeq fev i opraups iq borbave nevdiét 2s yilvesd aa dosdde fo ifeds egatw osed Lrtpacoss ed {tiv ebedsan tallate edves soot ; ‘Yo. tedneredo® ocd, at Qaano sqadteh. .aslo Ileds Srad ons | ennse:0 sic abooW adg aiil ascesq atadies 22 weised odf : enupat ffiw sidetante® ta gatam 3+ sotiedioent oldqare \.pegook 03 widiascy oc tat 32 .O8En amiedanp tw gntsise pete nt bon (wean vray et gntéjon Lecwiss avadv saota. ots oesd? .basg ot) Bot souteise wf nso amet 6) sae fife eagivh Ja ssatsotcid eft to anc tadg aqrssitdis | 8 . ; ome aids esolq: . 7 fet ,2t dite gol spor saskoss ajaubery eds edt) (82-1 g mdi Tish 2 totape loves od? 4 se aks ack Pitious im. swt V2 - Sauce bracch +44 Ted 4 ,eldati iow sacced ‘AT ROTS gate ot Io yerae & 2S itia, ctutrsiat grtsub gotessst Son etteulhal, say Aaucitis boxvimis “rev st ai epbes> Ww Aened BouG én ak, 2clane Ja Yisaiao @baniet wii anos abet oT word of Sdarmynh al 84 = $as. tnamosansn ragoty ro? : :PuUOT TOsHOS Higem fd Clinwh st goat seanng) Nw ceiedatt guadedp act -¢ —si wodayo adi tte aatdo pabetel yd Bednaqxs 94 pines pawint gio! at vitae . (iit? © No field work is anticipated here at present but fmds have been allocated to Dr. Loosanoff at the Fish and Wild- life Service Shellfish Laboratory at Milford to develop methods of artificial propagation. This work will explore the possibility of producing seed clams in hatcheries while the field units in Rhode Island and New Jersey in- vestigate seed production from natural spawning and set- ting. RHODE ISLAND: An intensive quahaug fishery by tonging, raking and power dredging methods is located in Rhode Island. Tong- ing is conducted the year around in every clean part of Narragansett Bay by about thirteen hundred diggers. Power dredging is permitted only in part of the Sakonnet River from December lst to March Slst and supports less than thirty-five boats, A serious controversy has developed over the relatiive merits of these two methods and the Fish and Wildlife Service has been asked by the industry and the State Conservation Department to settle it. Tongers Claim that power dredges tear up the bottom killing the seed and breaking many of the marketable sized clams. Dredgers claim their operations cultivate the bottom pre- venting silting and increasing setting. Dredgers want additional beds which are too deep for hand tongers opened for the use of power dredges. Two biologists are now stationed at Wickford, R. I., and have just completed a survey of the hard clam popula- tion throughout the Bay in cooperation with the Narragan- sett Marine Laboratory of the Rhode Island State College. This information will be used to select a representative area for experiments to test the effect of hand vs. power methods on adult clams, juvenile clams, setting, and re~ lated bottom forms such as fish and scallops. Part of the test area will be hand tonged or raked and another part will be dredged. Equal amounts of hard Clams will be removed from each plot. Periodic examina- tions will show the effect of each method. The results of this experiment will find application all along the coast wherever controversies exist between hand and power methods of clam fishing. Seed production from natural spawning will be inves- tigated this Summer by the Rhode Island unit as a beginning of quahaug farming studies. Although clam farming is not - permitted in Rhode Island at present, the methods developed here should apply in other places. (-56-) hare tas ia peihe- ata ae te Aba ave a, bay anit 4b Crotgiudes Hal, VLkgse ootviae wwe | hp BROW efi’! aationeqetg fas tt 25a) 25 “Shontem “tpl beh iow oe ited Dabwwhow tc yftiidiaded aft bet Greidl gieeh adi adie) Dlort $dy-altiy get ous =m? volseuhorq Sean -atont leey ABy { a) a. . PQA ISS, ONS f giawed wl ovrwist'! alintote avianeial oe } se0en a) hovane) 2! ebyAlrer gatgbeth tewog mors Vise. i!) Dingta a90% Oey Deen Pal mis meat: BD SEthrhsi j'c* rei. Sea “eit vel siwenaaa trol i 9 ee GA Ty faiy MO Pleo Pear reteg af Zekpveth _ Sa cas cae" “hs Sufi deta wh «al Whee on: wou 7: pl ae COOP THOD ai Cl Se hk FF Jan’ welseyewtt) £ ny nt) ies rin pod) 16 WIL aveioies elt. 4870 Weuva weal! wed solvxet? SBIILDLES ban ; orl im a eat oat So ones peg paldevreand? efafh. ead * ee MOS FOR, wits Wl “taod aepheth saved fad? miels . Be. B ettiates ~« eid Ya Sea gniiatwotd baa Boge ; BPSTrdio onetTaege Tiedt mials qieghe aie ‘ a e & ‘ Bei « cA eee af spunea bae Sridilw BAlinav 5) Rebel Wat wich ool vtta Avdde abed Isnotsibba : Soy wwoy Ta neu eh? 9% Sefettccu £0) “an efedgriald avf Ty goruy 6 Dagadjuns fewl oved baw - 3 Biacs of Bet ahd Sirgageronte Nols Bi is to piptetodak sap fisa s | a6! pa) SEF 29 of pagegotal aint ge8 tacit tm atsusey +94 asts S sites, . ls ths 19 ebetyen Mésrt ws ciete onrree meadoed Bygul s : we4un .¢41! 02-7 oat _* a Bed Lich Jue gedenn Sits GR foes ttt be vont eS Siw ensfo & te tov on one wortw, itw enold : +t am . Ce a& sal | al ie ih TL: a » ‘ at steal / ea, —_* 7 ite A management study area is also planned for Narragan- sett Bay. One part of the bay which supnorts a small fish- ery will be observed and records will be kept of actual catch. Methods simiiar to those described for the soft Clam studies in Sagadahoc Bay and Robinhood Cove in Maine will be used to arrive at an estimate of the sustained yield. This estimate will.then be compared with actual production and correlated with quahaug population trends in the bay. Management methods developed here can be applied wher- ever a State Conservation agency has the responsibility of regulating the fishery. I would like to close with this thought, The program of the Clam Investigations is flexible and can be shaped to fit the needs of each area. We would welcome sugges~ tions of the industry to help us establish studies which Will provide the most benefit to all concerned. (57-) a (-ta+} THE SPAWNING OF QUAHAUGS IN WINTER AND CULTURE OF THEIR LARVAE IN THE LABORATORY . - a by~ Ver Lie lecsanoftvand) HalCeDavas U, S. Fish and Wildiife Service Milford, Connecticut The success of any shellfishery, including that of the hard shell clam, Venus mercenaria, depends to a large degree upon the availabisity of a supply of young individuals, commonly called set or seed, which can later be grown to marketable size, In some areas sets of young clams are heavy enough to take care of local needs; in others, which unfor- tunately are more common, the ssts are usually ir- regular and light, Realizing the importance of having a good supply of seed Balding (1912) tried to raise young hard shell clams by artifical means under laboratory conditions, Unfortunately, Beld- ing was not successful, because most of the larvae in his cultures died either before they reached the straight hinge veliger stage or soon afterwards, Belding concluded that there was no practical method for raising hard shell clams to the setting stage because of the small size and delicate na- ture of the eggs, Nevertheless, severai years later Wells (1927) showed that by using a certain technique clams could be propagated artificially from tne egg to the setting stage, Wells, however, was mostly interested in oysters and did not con- tinue the clam work, Our entrance into the field of raising clam larvae was motivated by several considerations, First, we still believe that by developing proper and efficient methods artificial production of clam seed may be economically feasible. Second- ly, if we could succeed in keeping clam larvae of different ages in the laboratory, a wide field would be opened for studies of the physiological requirements of larvae, and also for studies of the effects of different factors of envirenment on larval growth and survival, Such information should be extremely imvortant for understanding why some areas produce heavy clam sets while others fail, Finally, the methods developed for raising larvae to the setting stage will offer us the opportunity to enter the field of selective breeding by crossing the individuals with certain desirable characters, such as un- usually rapid growth, etc, The latter may ap- pear somewhat far-fetched at this time but we believe, nevertheless, that selective breeding of commercial mollusks will become a reality within a few decades, Working with the hard shell clam is not new to Milford Laboratory because one of us has been studying intermittently various aspects of the (-58-) petty iW anette SS OMMIMMA Gar | i : SANT AAT 41 - LAS ) “HU TIVO GHA 7 t- ; ] ‘vi noni mt a! a¥ : . 74 L' | , 4 i Lh . ay a Sant? ‘ ‘> My ye 4 ? ni ; ® fate Lode btm om egcw ? wel Gaituab ay te! ns roant (reg sc Hu Mate bert mid pr re Wo. Biel? os oe Reece 10 ' Ft pata Ioueves Va eertom asv opvial ah rm afl Ved | 1 ad wghs ge: €iive id atk feteo my Leb: 3 “dew tolTie Gre, eee « eced Vette oh. caer yap hese male Barrel ‘Srigees rc : ga Duco ov 22 AD od iw s mage a" i‘ hae tet Mee wie TB 40°. 1 molto a6 blvov.. ~ TO} oats t s VRP io atteemvelvper © a fed) ro TEL) 10 atentia ed? ne ke erts + kere e no “ fog. Laviel po Srmeitce= | bods vefze ad bluode re bisa prt ura a9 7 vay, ft aro8 oS Veet 96.79 @ hd anos baqe fsveb fs ; om onl , ‘ts! . €£iv eyes gnivsee oe oo pc's ot ant Bey Bias? ois. $6fra GF Wines AE slecbhtvliat eff @alweets wi ynitess af “(at es hous of setae mic etee ' “qa the teliel OT .Oim j,i - eulteeri avitosise seg) ,bsoles = a empha Aida Ban lcm: x Ji Aang oe on ton ut ueke fos Beat es tw got heed st ay We ad save te Bar role ef tO s2oonee sane tras sy Sud ooh? aia -3@ "adage » a om a sie a clam'ts biology for the last 16 years, Our first extensive experiments on raising clam larvae were, however, undertaken some time last summer, Clams were stimulated to spawn under laboratory conditions and several cultures of larvae were grown to the setting stage. Obtaining spawn in the summer time is rela- tively a simple procedure, During the summers of 1933, 1934 and 1935 many clams were induced to spawn simply by raising the water temperature a few degrees (Loosanoff, 1937). However, because the spawning season of clams in our waters is confined to a period of approximately 2 or 3 months, experimenting with thelr eggs and larvae were necessarily also confined to the same period or time, Fortunately, since a method has been recently devised to induce oysters to develop spawn in the winter time (Loosanoff, 1945), we decided to apply this method to clams also, hoping in this way to extend considerably the period during which ripe eggs and sperm could become available for laboratory work, The method was successful, and by using it we are now able to make clams spawn, thus obtaining their eggs and spermatozoa, throughout the winter and spring, The method was successfully tried by other groups of investigators to whom we described it, It should be remembered that under natural conditions there is a marked difference in the condition of the gonads of oysters and clams during the winter time, As has been shown (Loosanoff, 1942), the oysters of our waters resorb remnants of their gonads after spawning, pass through a stage when the follicles are free of all but the indifferent cells, and then, just prior to hibernation, enter a brief period of gametogenic activities during which ovogonia and young ovocytes are formed in females, while in males a few spermatocytes may be found in some follicles, In general, however, the gonad remains undeveloped consisting of a few fol- licles scattered in the form of small islands throughout the connective tissue which lies in the area between the body wall and the di- gestive giand, In this stage the oysters en- ter into a long period of hibernation, which in our waters lasts approximately from the end of November until April, In hard clams, on the other hand, an active and very rapid gametogenesis begins soon after the completion of spawning, and by the end of October active spermatozoa can be found in virtu- ally all the follicles of the miles (Loosanoeff, 1937a). Thus, excluding a brief post-spawning (-59-) 7 e 7 F é ett wo ,wieoy of tent ont wi wyaltoid winifo geo OAVERE aly yatetst ob Eo mges svisietss Save teal sel? aaeoe pa Celine * prodal toi cowie teralimnife stew - ee? oF eiow oaysel aaqeitic Ci teves bas 7 asta. gutiioe —Siex ‘a? om! towers, ody ne aid tetetdd.. as eteraps ois. snigel eh try Olea 6 vLevis ‘OF feandn! ocuw @eta gan f tere “FOE pEFOL B.StUi eve apse set soa vd yluatt mwage _ ,wvve uw “ Veo2 nae | apesean wa? pe =r Soares gilinvege Srl aor faVrint hi a twig ones Se msell wun bos sees Walw ant coukieqes gine gala vyifteacooan awsyoT Sul? Biv Yivieaet hea’ al awoqe - gpaicvat Ew i ee rie Ht oo? benltaoo ie ie ee at emcee) Odilivt Otetat ght smadarh) am’; qe Le ap BF Suikicy 6); IniitessS bis) wotove er.35 aan ate iw ands nt pe Alt Fiea ke teintw gotiwb Pan, ton ginatabdal 10% aldal(tove i bta awi7! asine Yo) doe =~ ePOoUE 2° Roy bag! = cae bd eof act ‘ ol oe a sian yet ee Be hrs Vili ip ee pete Bi mot ag lana ham lf Cyvornly. caag. | ed? tnd ffa To eck oF ghey,” otme tele’ 4 me Fee year, In the females the proliferation of follicles and growth of young ovocytes is also very rapid during the latter part of October, Towards the end of November and in December the ovaries al- ready contain mostly large ovocytes of mature appearance, Thus, the gonads of female clams collected late in the fall or in the early winter appear morphologically ripe, Therefore, if we compare the gonads of clams and oysters in the late fall or in the winter, we shall find a striking difference between them because while in oysters they are in typical winter condition, containing only a few immature sex cells, clams already have either fully developed sperm or large ova, It is possible that this difference explains somewhat the better viability of eggs and larvae of winter-conditioned clams, as com~ pared with those obtained from oysters condition-~ ed in the same way, Our method for conditioning clams to spawn in the winter time can be briefly described as follows: Clams brought from their natural beds in Long Island Sound, where the temperature of the water in the wintar time is near 0,0°C,, are placed in trays of running sea’water having a temperature of approximately 5,0 to 7,0°C. Then, at intervals of 3 to 5 days the temperature in the trays is increased by several degrees, Eventually the temperature is raised to about. 22,00C,, and the clams soon become ready for spawning, The entire conditioning period usual- ly takes about 3 weeks, but can be made even shorter if the intervais between the increases in temperature are sho: tened to ahout one day, or if the clams are piaced directly into water of a temperature of apovt 29,0°C, Under the latter condition we were able to make clams spawn on the eighth day of the conditioning period, Conditioned clams are induced to spawn by raising the temperature of water to about 32,0 or 34,0°C, If the temperature is raised above 34,0% most of the clams usually withdraw the siphons and close the shells, It was often noticed that spawning begins during a decrease in temperature, i,e., if the temperature is first raised to about 35,0°C,, and then gradually decreased to 32,0 or sometimes even to 28,0°C, In several instances cases of spontaneous and apparently unprovoked spawning were observed at temperatures several degrees lower than 24,0°C,, which had been considered the minimum at which (-60-) °% a ~~ “FU 2URSV Io aglow 4fuba af 6 Bard 8 oo oy 3 ood See ae satact og: sey eye ToTet oe pa? 7 jose £ este er obybfone eis) TARY r s aE ELOY Be (Sig eds 257 MIT ot orve 7° vv» wO"s Dae SiiF . 2 Sag f of unlacb i “ir tai kein iat 6; i. to has a rita vee nhoe Pies 7 : kant MASUR eiy . zur) Serer ; watnl #7 * ta J Be oft S ? ef taj f: fT as i ¥ a Ps WHAT Uris c Mi 1 SHAQTS a 7 7 at f $c) enue h oF PWS gries _* . WW. ghesatw 9 mt “0 Fist e3sf - site _ ; we exo | ie. Sots d 65n } fi 2 UBS, Ps oy CADE: Vw cz : o ‘ . a> eget 3" 4 sa Peirtes ty *s pel ‘aes 7 > ° tee ‘832! we foe, al fm: band yp BisV {> Ls «tan y Ri ie Men . nt a Pl et Bieter >F> Bit,» a aa r i Avabale aS Rare bs hy eSRA8% sag - geal 7 | OO 2aO Ops a Tavau ofa. bod.. sPAgU nants €4 Wf » al Loe rvede Ww. ke ‘O,SF tuoda ni a PO. de Ovods foals a ecofgis on code wt. fc ‘boots on we PUVletrsiness ; oF e fa cash ¢ thy ae Fa) i iw jal Sone MicaB Xi bechesy monty. Seen ey . “ (0,88 ae i Os. pe elige Os ape and gage ta he «oe as > & > a ae ae 2042 %e ORSEG & 2d a few ars peta aig vor dottw to pinta std mI .- clams could spawn, For example, on February 7 and March 4, 1949 clams were seen spawning at 22,0°C,, and on March 28 and April 5 large groups spawned in the trays having a tempera-~ ture of only 21,0 and 20,6°9C,, respectively. In all cases both males and females were spawning, many of them quite profusely, The eges from these spawnings were collected and cultured, the larvae reaching the setting stage, In the first two cases the clams had been used earlier in the day in spawning experiments dur-~ ing which they were subjected to a temperature of about 34,00C,; however, after that they had been moved back to the tray of running water at 21.0 to 22,0°C,, and remained there for about six hours before beginning to spawn, The third group, however, had not been exposed to a temp- erature higher than 22,0°C, for at least 11 days prior to the spontaneous spawning, and the’ last group, which spawned on April 5 at 20,6°,, was just transferred there several hours before from the conditioning tray of 15.0°C, Regardless of the nature of the factors that caused the spawning it is important that it took place at such comparatively low temperatures, thus sug~- gesting that in nature clams can also spawn under the same condition, While conducting the spawning experiments it was established that spawning of an individual clam is not completed in’one day but is spread throughout a long period, For example, in one of our groups a marked female was induced to spawn on six different occasions between February 2 and Mareh 3, Many other animals of the same group spawned several times, In general, this group provided us with spawn for a period of approximately 5 or 6 weeks, before the majority of the clams became spent, Contrary to observations on oysters, spawn- ing of which can be induced by the addition of a suspension of sperm or eggs, clams do not react sharply to this type of stimulation, The mijority of rine clams could not be induced to spawn by the addition of a suspension of sex products, However, many would respond if the temperature was raised several degrees, Apparently temperature was a more important factor than chenical stimulation, Not all the eggs discharged in our experi- ments by the spawning females possessed the same vitality, Probably some clams were com~ pelled by the strong temperature stimulation to abort the eggs even if the eggs were not fully ripe, Such eggs usually developed into feeble larvae which soon died, The last batches (-61-) , 44 bs = Set id | = | . @ gi ae % i ; 7 ” : f 10 ve - ’ rl : 58 rae ‘Te iy A (roe ’ A 8 pati Has. 21 A? Big © q Zz nal : Fe , oly ~ - ; | bw , 5.53 ' es Vil Pec ‘ . : ry * ' acuoge ew =: 17S wf ~ oc ' th j ™ nl etd _ | o 7. * arti? ? : : | | a¢ = | s es pes 7 “ye a cans r ’ | ; : 1 en, oe t. @i } eater | 7 wail! “4 ‘ = 7 he ted foo aes | w-ge ti ; - 7 a Wei af} | a 1 aes » a0 eo - yj af 9 7 AZe9 = _ iy 4 > \ ‘ if rot ce e - 2 ,FE VOCs : dune he ‘ 7 < b= i-1 ~ @ ad Ok let! i : . ’ - 0. Tak ° eat . 7 ’ - oF Qo is aa — : | P 4 ~ { le | ard 2) WO Es ; - eb sgak rte - Li Saeed ae > ae sod .gnoTs Oi ii j hts hag ; ss | “oO P A Ape | : 1 atUITS ER’ = Coosa: ’ rads ime n.°S OF Lf bth we 4 e~pdkd bhi; nn0 ral G ai 1 Cox . y., (Woty exalt Merge re =) 722-7 32 oh : nt nf Aas : i Biv ui oMmetio® * Prhcop | aan i. > : - « } 5 : y= iy cyo i? oa 3% rag q Fos } ‘i | | =d 4 Pane \ P ‘ SO tell eny I —o Orel .. recs pit ab $i ache ; _ a” ‘ we ve piel a : pod aa A ; e U * or) A of 7 ¥en, ati : e * De 4 ry & Vey “ . y% SM! ae =] ats Sits a7 Far rm ; ~eirnt. * re tae oh ¥ | 7 het oe My Laens ) ’ a oy) os : ea | , a ’ ¥ LS ein “* Pp A5RLne FeO vnc , 's ay tua c : hs See ea feta Sua Ss LS a ; at ie > pr ated hs oie! ee 48 | 12 0 Cire) A Py Va oa? On v z 4 Lng Pianrt eogele rep be ee bd Ls c. &§ 225 2tE(s or 3 . Ly 5] rer. 1 Se | Pte a ie ©f eggs discharged by virtually spent females also fave feeble larvae that grew slowly and showed a “igh mortality, With a little experience, however, =f investigator can learn to recognize various “ypes of spawnings and select only those batches et eggs that are suitable for cultivation. We Sound it rather difficult to induce spawning of <“lams, which were about 4% inches or more in size, “aller clams, measuring about 3 inches, usually *e€sponded better than the larger individuals, The eggs used for cultivation of the larvae *€ve fertilized as soon as they were discharged, -O separate them from the debris accumulating in “ho spawning dishes the eggs were run through a Stainless steel sieve, which allowed the eggs *O pass through but retained the larger parti- f£les, After that the egg suspension was filter- <4 once more through another sieve, which was fiiie enough to retain the eggs but let the “ater containing the sperm, blood cells, etc., Pass through, The retained eggs, now free of 611 impurities, were placed in fresh sea water in the hatching jars, which were continuously AeVated, _ The eggs and later young larvae remained undisturbed until they developed into early VGliger, Then the water in the jars was renewed about every second day, To accomplish this the colitent of the jars was strained through fine Sleves, which retained the larvae but let the Water pass through, The jars were then filled With new water and the larvae returned to then, To feed the larvae small quantities of mixed Plankton cultures, consisting primarily of forms of about 54 in size, were added daily to each ja®, When the larvae were reaching the setting Stace old oyster shells were placed on the bottom of the jars to provide a place for attach- ment, or the larvae were transferred to special aquaria on the bottom of which a layer of sand WAS spread, _ A description of the development of the egg ant clam larvae has already been given by Belding (1921), Therefore, it is not necessary here to 2° into most of the details, Instead we shall Offer a comparatively brief account of the development from fertilized eggs to the dissoconch Stace, as observed in our laboratory on good batehes of eggs kept at about 22,0°C, (=62=) ) eretontbcegye RY ole i > ufiiss a) - - ~» @ ra - bd : f ry 1 ° ¢? ia : " ! _. } 4 T va - , : ? 1 if 4 id b i ’ : 4 i ” i W732. aol 3 ' =: kK [ , ® 7 i 4 ' >» _ ' Lai ‘eo Tr an 5 + : ad i, / io , 2 |.) « ¢ £ ) 2: ; 8 imo iia ic * ag inte? s 6 " . 4 - = 5 ‘ hy > 7 id 24 sds Toe tee { ’ ‘ >" ‘e v ce _ ,bacgnte Ves Ve. hi v1 j oY rerni Db (T ’ “ltas oont b vaad f drnuver fine ’ pevenat (ev tal mysw stag htev © Wed ater Merigace-« ; va dui EGlT ngvanity tenlncds z . hare gus Sai tl eevrat ar sits oidw ,fayes Bbatlit mds orew a7 C wel sar? fara we té men? oF teirrivies esyte! od’ bua mtuw wou “ts Semin 2oO°us hi isms flexes saris? od? Sot 01 iet0'2 > ere a2 er! nos: ,aetuiitve ro Fol i is} GO6s OF XIZAb PSGbs stay .e/xis ct *2 Fuade 19 ) VRE 780 SH? QAieeegy Stew geviel scr netW Me Ome: ie POPRLG B16 vifora * “6 Blo o,57* efoats® 40% enale 2 abivotg of 27 if to mod tod fi bbsas OF Sp ri lenet? etew gavisl sd? ao , jee - “Oi 7) tavel # debi Yo motiod eft co sabre ; ; haorqge #*6 - : 7 7 G99 9) V6 TaRoseTes ete to, woliqtioesh A galled q! cavity oad MOGATIB Gari eévtal gato fe QF QiOn CicEeDOOS FoR G2 9h ,etotatedT crsere crate res uz. , ‘Fl 69 GRignd Vint « te Buas 4 fips B« ° hia a ce sine ee Flame & ,2ekertgos; Faeuqoroy at kaa moat fia. ta Ps wes ou atatT - ,Lemaios eee 3 ba wolrevatis OM Wied “ae re rh aye Bye 20) Se tte «=; mevertay 7 re?) ies Cer Tish: to kaw: ie Wi tare’ 7 hy mp! A » a ] ; Mew ™GHOIS « - ws ; oe .’ Ra abe re wag Wels sir Halo Be, WIC fio ms oO Wiewso8 : emOAY Of cle WE) er Ni ini ye do) sogoy wu ROSE - et de A hn gel drt euyl! ve ql Te aavrel naar of MAY YEE. OG! “YO 22 he i he t) ‘nae os. oe apties big “ESA tOataNi 4 ida t 30 eR a Rta. WHA Tigi vs Livro > ved anbirs ©) > = “Ete > a) ee 2 é ‘ L efn PIA 7 7 Pe vi ay Ko! ma sb atias od ay PP uyg art rs i a G4it205 *~ » “FS - wits, Ase. 94 } ° om? ttn? 7 - Peis SAClE Gh drape), Ser Bol Vt tt \ CPRerE wae!) ge Oat mW! wivigiete: Lies Pad Foars? ’ Ge asx 2s pons ne a ae 7 2 ES > Sate iT oced ' SOME SORE Tae “ paikrdtae "Teh aes” “hitttat 26 ter 4 ene “angie rave: rh. a aan sake’ >; iver aa’ Metenial ~) aed ony Io sexta 643 YISV TOW ROTTS aes oxic ~ oie to 6 ame o Lid ley aes eat MOS ‘Slos akgongs - enviar todo oft. 3t0degomm: gga l* Dol a9 OSL ylag. otsu & ple ie ' _~ Ss 7) 7 —fmi'we-bot) adj Ta to omy mor: a & sWilOWoto To Yo WS ektesed, seit i. _ Bitty. ,etoces7 LoeiAy To Stine nue eino toffee OW) "DS. COvSe > oii Oale Hise =F : ho te titp’ ows cS La - to elanhlv: hat Lin ‘teats esgilT +L Ate on ae pidexvingr gt bowno b 20 Xoas 3. saw ‘taaqqn % traves uG eeititequer wot Pes ais ehoe SARE a | : ft i: a W ot Fl a) Crust): BoD" pit iv oer . A gM gal’, Eweew 7 _ foe a €at Bao ii a) enw irwort> nol n3 7 hey at be Swng, on? . : a, ? prea : Erubive bat ~ te shior flolto ef Feopjisl. - ' ts : e - Be open hh th th ian Borie Wa ¢ a ‘he while the larvae were still in the early stages, some of them would survive and eventually develop into normal in- dividuals which would reach the setting stage, We found that the method for staining oyster larvae, which we described some time ago (Loosanoff and Davis, 1947) is also applicable to clam larvae. By using a weak solution of Neutral Red clam larvae were stained and thus became easily distinguishable from the normal indviduals, It is believed that this method will help, later on, to study the dispersal of larvae from the place of origin, their rate of growth under natural conditions, etc, Our experiments showed that clam larvae are not too selective in their food and will survive and grow on- different diets composed of different micro-organisms, in- stead of being confined to a few forms, as the larvae of O Pmireinica Sseenmito, be. The execption was when the clam larvae were fed almost a pure culture of Chlorella, The larvae so fed grew more slowly and showed a heavier mortality than these which were fed mixed plankton cul- tures containing different green algae, flagellates, bacteria, etc, In conclusion it may be said that our experiments showed rather conclusively that cultivation of clam larvae to the setting stage is comparatively an easy matter, By following the few simple principles and rules given in this article mature sperm and eggs can now be obtained on almost a year-round basis, and the resulting larvae can” be grown to the setting stage even in the middle of winter, In other words, as far as research work is concerned, we can now accomplish in one year as much as could previous- ly be accomplished in three or four, With the method well developed and with the possibility of using it in summer and winter we are now looking forward to carrying on a num- ber of experiments devised to study the ecological and physiological requirements of clam larvae, and to begin preliminary work on selective breeding of clams, SU OMEN AC ROY — SE SS eee The method is described by means of which hard shell clams (V. mercenaria) can be made to form ripe gonads and to spawn under laboratory conditions in winter, The me- thod of raising clam larvae to the setting stage is also described in detail, BIBLIOGRAPHY BELDING, DAVID L,, 1912. A report upon the quahaug and oyster fisheries of Massachusetts, The Commonwealth of Massachusetts, Dept, of Conservation, pp. 1-134, JORGENSEN, C, B,, 1946. Reproduction and larval development of Danish marine bottom invertebrates, 9. Lamellibranchia, Meddelelser Fra Kommissionen For (-65-) In sone. tenets “freq 12 wl 22126 eve caves a wit etrdw nt Lanvie Gank: yates) elt ch, omer livers tuo asd? Leaertergetizan « ioc? five Goi ay «~lépbivib Bvisl Oe. we a imiats int Saas oa? ser furgeres 4 SW 2 owl tore dre wd | ) sabe teditusseh ow cloldv BSV.o Fels VO “aeesdt cele, « glllgsiines wet abt eves it? Des, Be = Stee Sagsn!’ Ge) >be? Lexie? to Holsyvioe pl yeh? ma gore vl aAteingseta b Uf tesa e400 Tes SW 4am povalfader ¢! slibgt : 4 eV! 6° : 73 ier vialt5 oh Vbitc ef OP gts Witrics | iM =F hSedevire To état tiadtt = cei} hoe ie th ae eon re 0 GPa OVi drs Li tw tex) Sold sath ch webs cofse Pebec nin Pas TLLE me Seay ATPL) Ro eT _ eae se ,taal 6 7 Oly bar YAacse sie? to peete bY aaw ne LY guns 4 £9 a iites re. 0 ome we Gani iih ater» Gf Get Saz¥ cave nl mal? Des tink qiwols ave mes fo t.oe Ssovaat ‘adT oy Seeigslm) Geew tin ity acadd: atts ydtlabron al? GATS (ata Pisses gntalainoo eu - ghia. shag end : Suecmsis. Wes At: Veg 2? aola Zone ‘nt B (aAviD bra Sy Cs beans. Poe nec ts, Guicsis CRS, Wai ea) e839 of Saciy apts bee art? od sole? Sere Palen 2 ne s> 6S getwiia2 Part ee Chee Sor vay SerrSeun eford te. alt VENy Sw Ope palit tages -“py¢ = Wewls no oa) Bet rea epi’ asdtao> mir of wry od Dies. 26 Tioy éresete cas ee obcov eerite nt 7 Oluind sa macs SAS atz) GE Pa cep: soa “ON Aho pngom St) ALY). iS) Go Gee mE bedatfomovds ad ef pire Aik SP sited 20 VEL ESR Stn, s/f viv twa beqofoveh AO Stay tis of ieevroy' gibt Fic ie am? yhete. a gaps aes stnomtteqae to seg S2VT5F wala 2B eeenrtiipss [nolgolotewiq = 206, LOOSANOFF, V. L., 1945, Precocious gonad development in oysters induced in midwinter by high temperature, Science, Vol. 102, No. 2640, pp. l24-125, LOOSANOFF, V. L, and H. C. DAVIS, 1947, Staining of oyster larvae as a method for studies of their movements and distribution, Science, Vol, 106, No. 2763, pp, 597-598. SULLIVAN, C.'M., 1948. Bivalve larvae of Malpeque Bay, P. E, I. Fisheries Research Board of Canada, Bulletin No. 77, pp. 1-36. THORSON, GUNNAR, 1946. Reproduction and larval development of Danish marine bottom in- vertebrates, Meddeleiser Fra Kommissionen For Danmarks Fiskeri-Oe Hevundersogelser, Serie: Plankton, Vol. 45 °NO, 1, pp, l=5eo. WELLS, W, F, 1927, Report of experimental shellfish station. Report, Conservation Com- mission, State of New York, 1926, pp. 1-26: (-66-) Growth Studies on the Quahaug, Venus mercenaria Harold H, Haskin, Rutgers University The State Universiyt of New Jersey, ak ka 2K ak Two years ago commercial funds were made available to us through Rutgers University to examine the problem of hard clam farming, Specifically it was desired to know whether or not it would be practical to establish hard clam farms on the same stable basis of culture employed in the oyster industry, As you undoubtedly know, the hard clam industry at present is based on the exploita-= tion of a wild crop and is consequently characterized by great fluctuations in yields, prices, etc, Our thinking in attacking this problem was guided by the experience of Dr, Thurlow Nélson along the lines indi- cated by many of the papers on oyster problems discussed at these meetings, Obviously to establish hard clam cul~ ture, it is necessary to insure a supply of seed and secondly to be able to raise it to marketable size with- out excessive mortalities, I will not discuss our efforts to secure seed clams - we have had some success in arti-~ ficial spawnings and some slight success in trapping na- tural spawn, but we are looking to the techniques of the Milford Laboratory, as described here by Dr, Loosanoff and Mr, Davis, to supply us with seed, I will consider briefly here some aspects of the second group of problems i.e., the raising of seed clams to marketable size, In simpiest terms the problem is "How long does it take to raise a marketable clam?" When one thinks of measuring a growth rate, the first question that arises is, "What dimensions are best used?" In our first year of work we mde measure- ments of length, height, thickness, volume and weight of clams of all sizes available, The first slide indicates the results of measure= ments of over 2000 clams with length, height, thickness and weight measurements averaged for groups of ten, it is seen here that when height, width or the cube root of the weight is plotted against length, a straight line is obtained, This shows that there is no change in proportions of these clams as they grow larger. These data plots are particularly useful in that if one average dimension for a group of clams is known the other dimensions may be obtained directly from the graph, For example one can weigh a group of 10 clams and im- mediately read off the average length, width and thick- ness of the group with an error of less than 5%, Be~ €ause of the relative ease of obtaining weights as con- trasted with caliper measurements, weights are now used in most of our growth studies, (-67-) glu Avigutarn S14 iV é jail ' yl 4 fo ant oun a frwo1d - : ctintecia@s> cre: giiret ,2\ffosoli esa wey ° ip vind eésad 9: : @*? ifdel tava, elim beat ‘ Paleo HAs e1se7 owl 1p esldierny iw SY, ita TLOwvV cv BTe a7! itgeronid form 'oe} tert cok 9 A¥: LAeottioma arta oslo. Dita Pred tal Gabes Oo kent? im od wwev.gh Jon so nettioxty pool gee epee Tics a) njdeoa were Sth nO 2 ‘tat @alo Weed eibotdvodc voy th oestatint todeve edt nt fax Peay fo Sastert Gh Sgesecd Je yi? sist ic wi Walo hried wel Sar ais “iyien po sod =f oan goto ALlw «a To nohs AIO 6h voy, ebIely =! ene Bt oud oul’t 70aTS | Sev as ldow ett? gettoatio at entaniidi Rin e elt ste? -asie ae. aé wo txastt (72 te evnstitsdm sd3 Bi) Miso) Sees wD eisce, 0:0 le ynee “t Gorno : =v ee- feliéates a? ve aie iwi .deekteoa oral? Ja | Rupe So -elaqt 4 Stiseh oF vw mksnosn wt 1t ,erd Sere oldetotrar w 3) actes ct elds af oF Ylhaoose WO \atvourd ton £f lu t ,sol®}falaon oviaesoxa Suo 4 serak Re Rel Ave ow - Soclts bags otr/nas OF ie Sno S69805 ome fen agelovede Iatolt faa vie of pAM GE a aw Sud needs Lows a ee a best e $csoterodal HiorlLn mae 4 Isiv i . Aree Gite te % qava 22 ,2'¥V~wl . Gos rom tide of) “c ine a7! war’ S303 leo ease i — - : getat ee: a pe lwegen to GG mate sst80 ot a enozagorsth Tacw” {88 200beo fat? setdvaip Jexltt oSaz 5: ¢ tow ic nee vat? tie a Oehees tead = ww bem omutey « Sanenbribal) vdtipted « dtpeet to shir el : o02¢ ahd ‘eae da [fs 16 alot Boer to: ativan ed Piet gata tenth yw aogdatits ,tdglod .digost dske tmaly | m3 ‘ ? to eqvets 107 begese¥se tineso wre : toot ‘edyd art tw dthiw Setyhon a tate o aa Pay tte @ .oignel Sartege 2 wieaiad «! $a tow Of 2 = ak otod? tad? ewods aitt . sonketdo -togmel wry yout as emslo weer? $6 nig tab ae at det? Ot. fetoev yirela ob te ot ate edolty steal ‘Wonk el amsfo ‘to quo 7 70% wolaneets. oactst ¥ mort Yioe71th fon Jdo ed yon tnatenoatd » ¥ j easlo of to quoty & ig tow neo ono: olqe ae ent bas Whiw . Wg! ogetove sdf Pio best \ . © tat aus of tO TOTle o8 tee Qeots oe a : al ve4* ’ es be ee ase. | “makes 90 wend Saget ' % a 2 eas. y ~~] #-etoK ,Tadea “ nt aiag sgetnsotog ges amals Jiogmel ‘W a Inftvalt? cata esx obits pat ; & Get eee ect _v pis? at 49 fed? to ator Pelt, 930 tacee tile faxight Seat ody Lapp aiteh drut See aveds ottla ari? © ett tottol¢ « d2wetg ovidelumve Lessieweies etn odd Gn SAT odd nt émglo.foos ,20 f Fads eloaars. wot vais ood!) ,2avtus —- aed aft af yaktates acetitonog an} taba fotnala Lethha na nl ontu welwotls of wor, Hivow Vel nk sete edeitte enbleibnoe Sao tet? =teay ovit. oF Seri? La entoo'r of Binge 4t Ss Daa settee ol TES nk tesx 1ce ont jit, I ehre ce ‘Ty 0) <0 t aT ae ab chien wee, abies vt! Pe ap a * “588 odciue »o %¢- be 7 Le balan esieeion? motrty qirta Saanors ‘Lazreriw ts vie ly e248 tevts 6.30% Jint? acls oi? |? at ; de apmret—cats On) saitac¥ oft e¢is raped aery rath" wor of Tyee tts .oote Saat a Sarid ion 7 * at pasp? Pi) ey Gals Tealisscoad inl A. oF : we colacthak soxd reviy Rava onecal” to? olcasius feng siceretienm wi tot 6 SUBLENIINGO NI HLONGI AISLGR LS = Wier \\\ SLs EA eo le a sean epg SS ne) AN OLIVE LP Loi \ H oO | (Page 71) SNOISNAWIG ONVHVNO T# GaIIsS > a 7 ~ in dae mi s -_ : = ii i‘ 2 TSKuGLe IM CEMLIMEIEYe WEIGHT PER CLAM IN GRAMS SLIDE #2. 6.9% ——15.1% Ce 15.1% ie cart SA: oak eR | | | | May Uti a ggg} jg TIME IN MONTHS C72 PER CENT WEIGHT GAIN ONG SEASON (SLIDE #3) ee ae ters si es O Cape Shore yy) Meso @ Ditto “8 ® Jarvis Sound ly © Surf City id ® Raritan Bay Fe esed® aqed 0 Ba otsid @ bawog alviet & wii Twe o Yet nattreh a weignt in Grams (Slide 74+) age in years CAPE SHORE 47 and JARVIS SOUND os RARITAN BAY (-74-) SLIDE #5 @ © Cape Shore Bast ee ae ® Jarvis Sound @ Surf City ® Raritan Bay FE = 1-273 x Const. S(om [See le lt _Final Weight _ Initial Weight LOG he 130 2n0 LOG INITIAL WEIGHT Cy) Practical Problems of the Propagation of the Soft Shell Clam, Mya arenaria 2 2 9 ae - Harry Wie “burners dav, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, ok > The needs of the clam farmer are essentially the same as those of the oyster grower, He must have some sort of title to control a suitable plot of ground, He must also have some means of seeding or populating that ground with stocks of clams, Finally he must have some idea as to what to expect in the way of losses from predators, natural mortality, and destruct- ion caused by other agencies, In New England, clam farming has never been developed to the same extent as has oyster growing, It would appear that tradition and nature have con- spired against the clam farmer to prevent him from attaining his primary needs, The traditional idea of free fishing in the intertidal zone has made it very difficult for private individuals to secure con- trol of suitable ground, In addition, factors which control setting are unknown to that once ground is secured, the clam farmer has no way of getting his plov seeded) “Finally, the effects op mumerous en= emies are difficult to evaluate since they operate below the surface of the sand, In 1947, several residents of the town of Barnstable, Massachusetts obtained leases on a barren flat in Barnstable Harbor and requested the Woods Hole Oceanographic Institution to conduct a series of investigations on propagation and growing of soft shell clams, A seven-acre plot, adjacent to the leases, was set aside for experimental pur- poses, Two methods of populating barren areas ap- peared promising, The first involved transplanta- tion of contaminated stocks which could be obtained from polluted areas at a reduced price, It was found that transplantation could be satisfactorily effected by simply broadcasting the clams on untreated flats, and the majority of the clams would dig in and estab- lish themselves quickly. It did not appear necessary to plow or otherwise treat the surface before trans- planting, The second method involved treatment of the sur- face to induce setting. There were a few records of intense sets which occurred on new flats created as a result of dredging operations, There was. also a former clam grower wno claimed to have induced set- ting by resurfacing his flat with sediments taken from a special thatch island, Several test plots (-76-) ; Tv so poliageqor Dent to eeeldost Lontiostt, Abtoiies exh mel Lier 2st er i . ob tong. : yaa _patsys tyent 5 bei ood 6." of ty 7 | _ ss atinaugloses + aoa ada0 ects alt “lo Zbesa Sat Maiecg. S29 Ta etn? ae suse : a Jone “Gl eItl? Jo. s166 shoe gma ovat oals sein Jaume YEE %e misote Wiwimiotg te oto wew om at fui of oe agbt sue ¥en ; ? D iipreraeh bas, po thes Seaton 2 cosaboug: gott eeazol . =~ 5 peblionega dio NE hseuso nek _ a . : A) ign ‘ad? apace podcast hag” - Omoe ovat fag. a .% ©) burety Yo tolq otda guedelined 19 on ad avieus tes shimcet mic ,insige werd, 17. ayo acc az asp) (Genk eft QF bodefaval Pian. bie eistebest tots twema Blivoweyt G? @pete: Bac 65? ahecyrecttie $3 af? .- wheom wiset’of ara sitinies ta og Inhta eet. ana] ff snttkes obTy Vo aisuS Stash odartss it Sie TIlb yey Hout ,weli ine ft ~-,hayerg olded sie Yo Low ‘crn Jets of OMe 27s, gitivigt Lorms ~ Se view op ee sen) atle sa) ,toiwoss ttt oh duantte J) ekDRSt bias JOLy _ onD Sarl) Gorse BIAS. 3 AteghtYrs ate. celine =| “ spree Sil) co Clete oa? wilted z fe aved aa? to A365 Sart enayes paved ae e best in ee: eg ,efdetentsd eo? warty af ialatas ot jal? Bap Sec a7 )]teet ebeectyamessd efot aboot ; amity

cote pieek- lelsrtmatags Yo moe : fecrot 2aWv thw ,@ott 52 =u y @ 92 costs botuiieg mott hedpe tis: Yi foTosTale Liies cottctasigenst Sede - gadalt Dedbe rigor s6 erg oa eee yt “lomla No * mates trie niigth Bison “2 yritot en of? One ie YIDETAO aN aeagee fon bib St .iefdetup aevioeaedy eu @vetad speak off Cnet? 52 lwioll>.1o) woldes ‘7 7 ° ne! cig oft Io Premtents Seyfovnt bodten + shwico?t wt a otew OtatT ,enllsoe erica ee is fyo iets -a725% wen no be rt90e moldy £4087 ; eosfn gavguetl .toote tego piebhep. alten feoulnl evict 0) Coaksig ony MOVE ee wade? £385 { : ' > r ux 4) ; .. were resurfaced with a variety of materials and it was found that setting occurred on most of them. The most satisfactory soils were composed of very fine -sediments which‘also contained roots and other fibrous mterial, Certain soils would induce setting but lacked physical properties to withstand winter storms and ice, It has -. not: been determined as yet how these new sediments in- Me setting, but the matter is under investigation, The problem of predators turned out to ‘be much more serious than had been expected, It was know that certain crabs, crab-like. organisms, and-‘boring snails subsisted on:soft clams but there was very little information as to how much damage these organisms actually did, Dura ing the spring of 1948,- severe losses occurred in the ‘stocks which had been experimentally transplanted and .. careful observations indicated that the: common. horse- shoe crab was the responsible predator, Laboratory tests confirmed the field observations, It. was. final- ly determined that a large horseshoe crab could prob- ably destroy as much as a square foot of well popula- ted flat per day. Sinee horseshoe crabs were very numerous it became’ apparent that clam farming could not possibly be successful vntil methods.of protect- ing beds could be devised, The problem of horseshoe Ee control is now under investigation, . It would appear that the prospect of Rercion ine ‘clam farming in Mew England is promising, Municipali- ties are becoming less resistant to leasing barren flats. slnere 1s a plentiful supply of seed stock an the extensive polluted areas which will rapidly puri- fy itself after being transplanted in clean flats, Surface treatment to induce setting also shows promise, If methcds of controlling predators can be devised, it is entirely possible that the clam farmer may be able to expect the same success as the oyster grower has enjoyed for many years, C27=) ee 4 how 22. bee -efe!te2 a te vtohrav- gcd iw Sosetiweat eters Saom oft) amsdt) 20 7200.. Ro Dewmatod gnittes Jedt-tnyat oh vse Bilt te bees, to Decomae @tew efios. +4 ofgataises Biiade evsotsih 1wita bre atdee dentstios o2fe’cotihw oo ae Bexonl dud gatyrea oounns Sloow alice aietsed _— - got bine exyore tatabw Boetarts tvo2 vo tdveqotd Phauwan ween | wos J8Y Ge SestaiaieS mead dion bees: Byiteevet nwbaw Bt TdF aa wad tud: ,satites pach HOM 9d 8 fun. benzos erosabety ae weldtota ont want?’ Mabel aiw Jl phe teegwe Boat 4 ad vad? evuerYas Paleietes alone gubicsy bam emekaagr oeh6 024 |, se'sd GA Hold ern: THE Steel T yiev saw oT 2 ie ent ; tte 10 i ee? Oh: Ef forrdoe agi heagte erent’ Ssenab i ocer Wod oF. ts 4 O88 af dotwoco nocaol atavor - sOUCL te. yntcis oe anal ips fosralqeos 3s? Vitstrect "SqN9 feed Rde doidw-etoads PF e@ 9c aaunoo an? jut beTasthnt Sno tiayrscds Lirle tas eritersdad tothhe tr Sidienoqgset of? acy cats. ona gio ae eow v1 -..engitevtedds Biett eit? foerit oo 2946)" I ‘aie Sfioon dats .odeGeiwot ayial 2 fect Sentatsieh ¥ | oy Iiow. Io FooY ateipe / 22 dow ‘Se verlaoh wld ; cot pad giants eorsor zr ogntc ‘- b nod Sal¥ bo) : elo dairy IHS CULO “Poss +2250" ; ies jou Eitou Siryeseoxre a ¢fsieeon dod Weldord at © !) eo gedad ed vow Mekti Lets fo isi cme seete apitoubor eft ef? (S) fue ,tilevd eticieg sie > ae Siadttw boo't gees oF deftllote errs “o Seisses SPaule ro noltasys i } beqqins grted foubary si) «> Veen bevatvnoo sift — - 7 ad a i= = ne ebaw posd tat dolte ebuds atti ty efooh ‘tegen elit eh To adrsit Nene ai "OF Bagfs= “n-d ‘ts. aste, Ligmz 9nd to | MokvouboTy Io o9svae go NA Yo 1k Te ptpeseg eal gabbto a * \ s0vaeh oknoest od? 22 wan! af (font) mf Aots oar .. ~~ *'petoa 002.E Jioda esate Zi 4 éc2o Sel gaehnalt Ooo ; ted ‘toy batitnsro egral hia orm soe Aohiv fort o > Ay \ Aiievoe fooubo im 976 ne ee : : So S81p ne seiyboses MW eredesosy Largu ent - we? wWhlews or at ‘&eint e2oy 1h Sat WOT. “py savey ofy. 24 qorice. eh inne oF {f) - ae ‘ao totew cethare Wo coltpeninars yodeipdal No ifiveet _ eile” gifiaalist enniies ss de Oomntsty ets | a waloes veatios oft Cm - a -\ a ay soot asria Sf siodsab pete osedt , ¥ e§a wsevie edt to dtaq ait brs ‘tovia. ade poole ate? Hoch To vodmun & ,1SVeW goteullog off ,coliuiteg gattuditiac2 estrodudird 2th —trh holttamiat yliepts ef saotv0e soviet seedd more) ,leoq edt 26 at goltcutow Mevb radw temnuc ast gah ; ar. on _ | seont yitte?ac By cine rd emt ot HolpLbbs al’ ew. ast a3 of & dotwi Badootdus efa..cond 42 sith Yotaw tfae aaefo to 20.M 00d, eens Tolsone”, om adT ,shtd to Jeet + Juoda To ffat Soe ott Of urs) f _ att One yess ac @ort sak —— tne et : ; P ep = Rett noftsuifog aape oF Foe =fiv eat , bead 19 via a treatment plant and discharges effluent about halfway be- tween the village and the mouth of the river, The treat-~ ment plant was placed in operation about 1936. it dsean activated sludge plant of modern design and of adequate capacity, Samples collected at various times indicate that it is well operated, Typical results are as follows: Results at Riverhead Sewerage Treatment Plant September 27, 1948 0 Raw Prim.Eff % Removed Final Eff Removed Total Solids OSes. Daly 5 304 66 Suspended Solids 616 106 83 au 96 B.0O.D.(5 day-200°) 500 350 32 48 90 Coliform in Effluent = Maximum M,.P,N. per 100 ml. -330 Toba Bacteria an Bet. = tT per ml, 610 The river also receives the discharge from a laundry at Riverhead, Admittedly, the discharge of untreated laundry wastes may have some effect on the river and may be a violation of the Conservation Law, Serious damage to the river from this source, however, has not been de- monstrable by laboratory tests, The greatest source of pollution of this area is the numerous duck farms located at various points along the river and near its entrance to the bay, These ducks are of the White Pekin variety and grown in large numbers dur- ing the Spring, Summer, and early Fall. Only a relatively few ducks are kept on the farms for breeding purposes dur- ing the winter months, A survey of duck farms made by this Unit in 1937 indicated some 21 farms producing more than 1,000,000 ducks annually contributed pollution to this area, The sources of pollution tributary to this area may, therefore, be summarized in order of their importance as follows: P . The duck farms, especially in the Summer, . Miscellaneous sources of human pollution in and around Riverhead, . The Riverhead Laundry, . The effluent from the Riverhead Sewage Treatment Plant, Laboratory Results Samples of water have been collected from this area many times, and under various conditions, since 1937. Fourteen (14) separate surveys have been made during these studies, It is the usual procedure to collect four samples at each sampling station -- one at each quarter stage of the tide, These are examined for coliform organisms and total bacteria, Results of these surveys show that in the Spring the pollution is restricted to those waters adjacent to the (79-) © od sae Jasulr te ? 14 eo. As Jed a Ph bead aE Se Ohiiga wit bag egcliiv xa ghiee Sante mite aay 1 PabalG aie 9 oe staan oma - te tnd tg. onbet ma? aeats atelqas f¢ Eieeclion wefgas! ad O¢e se? itess Ia*iaty? Se t J7e[48 srand et Miu XA = ees mr eT tin. — ‘7 ' » he ae 4 4 <— 7” «ban ‘ ‘ ' ‘f uu i Rw ppeiaets ale eo viese: ants tv: it myst Som To eyrelesit ens yibst 1 2mbh beatta vil ja ror Bvit ef! co wan sie te ena 4a van coveal vt dwonl Pieeb sverias = WAL. me Martetss) pa} “o soliainty.« ad pmed Ton gal , rere yoowloa alld woxt TwvLT Mil oJ et pes Tres es iat ee phigtivocm . ae : 7 2 aa ; ab 2 Gai a epie wlio; gqioz $2” ts3 basteers: ern a=!) va § ; - F a3 aid at. der? tesla ce yovme acaas tok pale exozeu S2ods @ totohvee 7 \ “eRe Py. duck farms, During the Summer, this pollution ex- tends throughout the entire area and even into Peconic Bay, In the Fall, it recedes to the immedi-~ ate duck farm locations, Chart I shows a’twelve-year summary of coliform results in this area, It is interesting to note, particularly, the vast extent of polluted waters in the summer months, Based upon these studies, the Department has adopted a policy of closing the entire area during the Summer and allowing the use of most of the area, except around the months of the River and Meeting House and Sawmill Creeks, during the winter months, The Sanitary Significance of the Findings It has generally been accepted in the past that pollution of animal origin was not as poten- tially dangerous as pollution of human origin, Re- cent studies of the relationship of pathogens to coliform in duck polluted waters, however, would seem to require a revision in this thinking. It appears quite obvious from these studies that duck pollution may have considerably greater importance from a public health angle than was previously as- sumed, The balance of this paper will be devoted to ae discussion of this particular aspect of the pro- len, Discussion of Sanitary Significance of Pollution Prom Doclkst Although there is no record of the presence of the typhoid organism ever having been isolated from waters tributary to duck farms or from duck "droppings" themselves, there is quite an extensive literature on the isolation of many members of the paratyphoid group now generally known as Salmcnella, This group of organisms is capable of producing quite wide-spread and rapidly progressing outbreaks of intestinal dis- ease which. in many respects, resemb7.e tynncid fever -- the death rate from these outLreaks ex- tending to something in the order of 6%, On the establishment of the presence of Salmonella in domestic ducks, Edwards+ reports or. 56 outbreaks of Salmonelosis in ducks, from which 12 types were isolated All of these types are recorded by Seligman“ and Edwards3, of the National Salmonella Centers, as having at sometimes been associated with outbreaks in humans, The pathogenicity of Salmonella originating from ducks is further demonstrated by Mallam+, Scott5, and Snapper©, who cite cases of human Salmonellosis resulting from the ingestion of ducks' eggs or products prepared from ducks! eggs, (-80-) ‘9 9 »~f ty AT et rae Fae wiki i 1° "City isa ~— S ¢ Sma, (alps ¢ CPS at? he ky we wie syargue rey tite i IS Ai ee Tee fora rt .< a 7 bos Aa _ rs pi Lol he ~— rin 7 = "> ; geese rhe =evleve’ a @wors T G 7 ei) as7e taro yy eT ; 7 7 76 tee raw 196: an? tp ,en7 : toil ay’ » abate, eusds cody i : onlin ae Gatzor= to ar bo * vol oi, Bala ot geld nif wollte TOUTE baltaa 3s, Bursa -s ad “ Wars TYOIy . — rhe uD GASIS Bes >t waar we PAS 2 OH . , ie : Pa oy a i sae ode Sp catinetthiyth et retins3 a : oro, : : ' fv i4e ty rans aes “ir =, Y eildtenay sas v4 Ro iT Pn Tanta oar sa. peed ne 36 -emlfulioy tad i o Algeso- eee autor! ra Pleriegne’ VIE okt - of eee is qutene distes ef AO watts éeo Sif el eee . 4 tee: toud pt wisttios 7 i ee sities EST feu certvscys @rieper cf shes s ‘Lge 7ptt, Seeedaeeeede aov) easivte Selvp 2 479 7 carr areas eee ute Sent 18> we: yes spi sufic on sg) ef ‘Oye Sey tags /etese 2 Lom wrinssy 3 2 goTk ae MAUS uf fede-e4- 1 shi? Yo ettaind-¢ PSTD wen Site. te Boag am Wales 1s cis to mojeeuorth 1 he oD 7 te peer! eins eet ine SO Sol 670 ee ae te a as . ae > 2pm 292 ae BpWiorot an ct oa £¢ dgeocteta ~ ~. 00; Dade ioghanan ane tt Sao, na iao—ts btedgy ei Mages gig 5", ste i= eine ‘aeut) cot Setdicd a aw eee es) hs Sb bit ah oF ee A Fest pers a Wust n> gers or: 2 Se Cc * eaeesh vr sie. : Soe = an nwo _ io c= Aled ,} " a 7 ‘a'sot Stes Ly _ f yhrnees |). ee art od ae ty oe i esr > tee oF | Sa AASSh OO yy as a —_ , : grag us; pris ite ip" a rv] igediy ni : s Gry ai weit 4 . ry é oh cub - a oo J "] > ! dit x sna? Uae yaa hater tat Yo occa iitgat ‘tw? tare ‘a FOR - er P srantt melee fac) B ke aly fagnag 7 Ssliel | ‘3 af i eh ied ‘S04 ao 72 ye : a5 2 a = SIRT 4” oe Ander : tars bet : ‘i & pant iS uae a2. enitiodia andi«o at e Dt ona ented $9.26 soe tonto ot ari? areelaetcivedt to¢e7 07H cond ortt ‘told bog ‘us Ie, ud ay eo 729 gi t : arf ane fen iced ad Seat? 2.3 it seeel. Ja. eire-739% ag * Megtr cc wii re ie Ie Ay demts? itiseen sise% ed? 2582 oF wehto al bcheahel fe KCvOaED eR uyet Srocit to wat? oh een 37 Slane by oy ‘Witaeae > wy yD im sae +1 ue. oe ey eed? io ap ieetosace aS. began ua O Levivar® ia ee=400 oct IT oe etnant ht sober as Be CaS OiyIOs erg. wet siqmentth = sock 1c ger rt hie q ‘3 ‘elfodaaiss @zart2> soc" fs tate loa 602 °c>=) -@apee fody than es ivess a pe te tego is. | - ea ities oie * aa 5 Nae de am ite WA! 43 a 7 siela: sates. a Aah achat pil 2 if ao ae — as iv? qt y) ii exi'- ai oes c he FeO fei ‘ei - ‘ “* Dt) ae « Hi 5a6 \ ee? sale —_ aa gate brie Eo At TOU teguedess ‘Sh. GAwie? Beer < Ghani Mant, ot OO), F89 Ser. oy 21%. ind Brie 3 Fi cea Rieb/ Sot uTh srs. ws Aa ve Hote SM $09 a, Sa ef sg, = RS BRT oe wt om kt 4 cr t pratt e me Find) ee ; ores salle fo 0h Cr Casts G ean Sige’ scents Be tikes olsesciiet um weary HOA afinoll “ia Sag tedi.ts weliiuisto Mow - f [a8 Svc. fo Yai csc ,. Me20W aT emus 43 4unty cel? oa at je Heelies) G3 wy ay ‘pokeatehlsaos ac wart hias Bo eredinon oud: 2S Bien 4 cailiesé meet Sort ga'rt veh memati ad ego Saat 7 iG any iy Paes TABLE I ISOLATION OF SALMONELLA FROM WATERS TRIBUTARY TO DUCK FARMS Coliform Volume of Date “Station MeN Salmonella Isolated _Sampte 872748 5,1, Flanders 4,600,000 S. bredeney, S. give 10 ml. 6/8/48 Be 2, Flanders 2,400,000 S; bredeney NOemy; Bea iee 2 2. Flanders "930, 000 6S; bredeney 100 ml, 8/2748 5. 2. Flanders 4 ,600, 000 S; bredeney 10 ml: 9/27/48 2 DB Flanders 2 "4.00, 000 6S, bredeney LO Mma, 7/12/48 5,2A, Flanders 930,000 S; typhi-muriun, 10 ml, S, bredeney Oyster ; 7/12/48 4,1, Flanders 24,000 S, typhi-murium 10 ml. 9/27/48 Saw Mill Creek 11,000,000 S; Typhi-murium LO) mma); 9/27/48 Saw Mill Creek 460, 600 S, typhi-muriun 10 ml. 6/8/48 8.6 Peconic 2,100 s, bredeney, LO smi. River S, anatum TABLE cam ISOLATIONS OF SALMONELLA FROM WATER ee FROM DUCK Fahls IN MORICHES ava ARTA Samples "eollesten May 10, 1949. Coliform Volume of Sample # Farm M, P,N, Salmonella Isolated Sample Sample Tested 1S135 A 9,300,000 S; anatum ml. S, typhi-murium mes, 18136 B 9,300,000 S, meleagridis ml, S. bredeney (4 isolations) 10 ml, 18137 C 930,000 S, typhi-murium 10 mi. 18138 D 15,000,000 S, typhi-murium 1Oemds 18139 E 2,400,000 none isolated 100 & 10 ml, (=53-) iat ae peti 2 lepinlt ar jenn ‘otem pari “a, NEN ae PF HNAKA Te, A) rept OBE ee ALU Ri aa Ae ete 3 pr, OE 2 2 agc8e me it nif rite Matt .2 000,08 . a REFRE me OL murs MANGE, y= fys3 9009 es G ELOL | Te Of & Got bainieel shoa 000,000 2 OFtBE TABLE III INCIDENCE OF SALMONELLA TYPES ISOLATED IN INFECTIONS OF MAN AND DUCKS ek kK Man_ Edwards No, No, No, fyoe. Outbreaks Cases Fatalities Total = Ada Types 1677 egrg_ ~~ 56 S, typhi-nuriun S57) 169 12 S; derby ie) 126 1 S, bredeney 16 3h. O S, panama 73 124 4 S; give 36 25 O S; anatun 64 165 1 S, meleagridis 16 13 ©) Man i Ducks Seligman? No, Edwards No No, No, Type Outbreaks cases __ ‘Fatalities Qutbreaks Total All types gue1 1107 57) S, typhi-muriun 307) 356 22 32 S, derby 3h. ay a a S; bredeney 4. 4 Oo 2 &; panama L6 oy, 1 1 S. give 27 7 fe) 2 S; anatum hg 64 1 8 S, meleagridis 3} - als O 0 Seok iG Fake Gk Gc aoe ke cima make Wok ok peor REFERENCES 2. WP. (Rifidwards 7D. iW. Brunee, ana A.B Moran Further Studies on the Occurrence and Distribution of Salmonella Tyves in the United States, J. Infectious Diseases $3 220-231 (1948) 2, E, Seligman, I, Saphra, and M, Wasserman Salmonella Infections in the United States, J, Immunology 24 54 69 (1946) J 37) eb Ra Edwards, 0; Weaebrunem, jande A. Bo oran Salmonella Infections orf Fowls Cornell Veterinarian 38 247 (1948) = OCC CR SEE Etti(itsSSSS WINTER- HIGH TIDE aaeenert Jamesport : = 4 VA aie WINTER LOW} TIDE ee i) AqUeH CRE : a) Aquebogue \ ( Wf E : 4 A f , / = (ee amogue Pt. - a a) 4 Sr ope * Bil i ' a 1 : a >.) _ he ee - BS Cae ll er he’ a oe a ug Sal 7 : . > 4 B.S ,~ i ar on 7 - (TASS SS) | ae “ss RITNY SAF HID =e aN) 3 : PRELIMINARY UBSIEKVALLONS/ UF ‘THIS PREDATION 7 YAU, OF COMMERCIAL SHELLFISH BY CONCHS Heo Heisk skis Melbourne Rh) Carriker, Ph. Di, Zoology Department, Rutgers University and New Jersey Oyster Research Laboratory. INTRODUCTION Baymen from many estuaries along the northeastern coast of the United States credit the conchs (Busycon of oysters on native bay bottoms, Thus conchs capt-~ ured by them in their tonging and dredging operations are thrown up on banks to perish or are destroyed in some other way, Colton (1908), an early investiga- tor of bivalve predation by these conehs, from obser-= vations of these snails in marine aquaria, concluded that they may not be as serious a pest to the oyster- men as previously reported, In view of this variance, it seemed desirable to make further investigations which will ultimately indicate the extent of such pre- dation, particularly on commercial shellfish. The pre sent report is concerned with a study of conchs in captivity; studies of the conch in its native habitat are anticipated for the coming summer, METHODS These studies were begun in the fall of 1947 and were carried out in the Rutgers University Vivarium in a number of 10 gallon marine aquaria, These tanks were connected in series with large siphons permitting the circulation of the sea water by means of a Simple air lift pump placed at one end of the chain of aquaria, Further aeration was provided by the release of com- pressed air into each tank through thin cross sections of wooden dowel, Sand used in some of the aquaria was obtained at a local ocean beach, Clean bay water was collected in Shark River Basin, and in the Vivarium aquaria ranged in salinity in the course of the obser- vations from 26,4 to 28.59/00, Water temperatures ranged from 63 to 77°F, Hydrogen ion concentration was found to drop after a time from approximately 8.0 to 6.0 as organic wastes accumulated in the water; sodium bicarbonate was added to return the pH to ap- proximately 7.5. No filter was required in the cir- culating sea water system since the numerous shell- fish used to feed the conchs provided excellent na- tural fiditrativons 6cix,conchs, 4 knobbed (8B, caries) and 2 channeied (B, canaliculatus)collected in Great Baya Nie de ands in Peconic) Bay. Long Usdand, N.Y, were used in the study, The conchs ranged in length from 2,7 to 6.2 inches and during the course of the observations in the last year added a maximum of 0.5 inch of shell at the ouver lip, Conditions im the aquaria were sufficiently favorable to permit oysters (~86-) Paggh ~~ ati 7 ry a a a — es er f Sere | es! 4, Ai 7 ? Ba shi a a : +a it 2 per ey T= oes 2 2 os (a “Te ; ayy prey eel é diaz dhl PVT) O42: ait SY TeY kaa p JA, 1S ves iT: a ee | gt avid vosteT, } aid = 7 4 i i” | | ie ere " _ 7 » ibe + Ca a ‘ ; reen et) b ork ® ro. Ake ur t Meee) UL Ohe se et! Five! ; Cees a heel } > Beieeia a 2% alec Sty) -| ‘ ae ; at C. > meg yal ¢ = me > if a arr a j * ’? = © =, aa 4 : j d ? rs a a : a Mieka fr ke Pebiat Ni shpat ee le a ae 41 407% ta ws § ig he bh roo — 75 Se ee ee as eb G is) in Fy: Rate : hae rehale Lol twee. 4 om CIT NTs (ee). RAD i mee 87 tite: Pigyacnca et Peas tan : a ed avis OT OIr AL ihe si) YW) aaFlore perhebod ds 7 oer: aro Sh 20. weyagcoring e774 4 > ori i TS Wot arf? Ai aed? ato iy wit erent ot MiPcaay A etsasic Ct ae t4 Sebvias ows a ings 5 seit?’ oP as ibe. tt Get Vir, > tedauu J pate Aviat Te a | aries Pits rey ver « ak ™4e6nees = ta, 7 cn | ° Heat ORS * > a ema te aint ah node rt waren as. Daskiy quali: 79Se ye i ae yew Heli oven weia® aa aT eh. ox ee” its : Ries is om | nad 7A a b ul » Ly maey ive ny ©: in ae a textes eae | beuites: wens i) Ce aa a Te hs eee > Soe Weseray eh ry SLOANA or git: a ate Dy 6 (Ose SMH Si oe 4% “Ve mg fe 16 sows [eAry wos : Lewy oO ees a Ss 0 " ae wi Ae ; - ; at TAS nS i we & mod tell, an re ape be | | a" Se ed | "y yh f se na r| 3 ‘iad a Pads Ae i iid Oy A Sir 5 ad <= —- ay: Lie = A AW ate. or is Pe ¢ Adc lol ie i 7s Vi a e ——-_ = a oer 0% 7 a cal). acetone saan! Te! Gt Pa eh ive retiree ep. PF) PA tote ») fatalyt wide 4 , aia aL TIE ee Bf wepor. shes SOP Sa yy We erat. Oi ps ta Rhee “ayein W Gieriser & S64 A ips ae a f 4 Wf Peni Site eet ‘hie any ¢ ere re eset w4 ut te oe and quahaugs to add as much as 0,2 inch of new shell. The shellfish used in feeding the conchs were obtained in Shark River, with the exception of the oysters which were collected in Delaware, OBSERVATIONS METHOD OF PENETRATION OF SHELLFISH BY THR CONCH, Copeland (1918) has shown that the conch responds very quickly to the blood of a fresh oyster, This mark- ed response is observed again in the readiness with which a conch will locate an oyster or even a clam buried in the sand in an aquarium, The snails creep at a rela- tively fast rate, attracted by the water pumped from the excurrent siphon of the bivalves, Nor are shellfish such as quahaugs which normally occur buried shallowly in the bottom, safe, since conchs readily dig them out, It is not known whether they can dig up such deeply buried molluscs as adult clams, Colton (1908) observed that these conchs will penetrate and consume such shellfish as quahaugs, mussels, oysters, razor clams and soft clams, Magal- haes (1948) found that in North Carolina’ these conchs consumed 8 additional kinds of shellfish, Colton's findings were confirmed in the course of the present observations, It was also noted that they consume such molluscs as the soft clam (Mya_arenaria), in which portions of the soft parts are unprotected by the valves, merely by tearing out the flesh bit by bit until the valves are clean, Such thin-shelled bi- valves as the edible mussel (Mytilus edulis) are en- veloped by the foot of the conch to the extent per- mitted by the size of the conch foot and of the mussel, leaving the portion of the mussel valves farthest from the hinge exposed and oriented directly under the outer lip cf the snail shell, The conch by contracting the columellar muscle (that muscle connecting the foot with the shell at a point within the shell spire) then very slowly and forcibly brings its outer lip to bear between the bills of the mussel, This pressure either forces apart or chips off a portion of the valves, The curvature of this part of the conch shell : 5; in spreading the mussel valves, and the concavity tne valves leaves a ready entrance for the conch prcboscis, In one experiment 3 conchs were placed in an a uarium with an assorted collection of -shellfish.. Within 10 minutes each of the conchs had a mussel enclosed in its foot; 4 1/2 hours later the 3 conchs had opened and consumed 7 mussels (0,9-1.2 inches long), 1 clam (0.8 inch), 1 ‘razor clam (2 inches) and I quahaug (1.6 inches), Throughout, the conchs showed a decided tendency to prey upon the thiner-shelled molluscs Pas Ge : (=87-—) Fe a EL a er rep ree rg ea a a a Sn ee en J Wen Th Pack FO ee doe 29 thw of tgredaue bas Of? pities! =b.teer el Tiled: on? % aoliqesss ot Atty ee oes aL : ewes et: Stns Lion etay eee oe aan a? ' a7 A CRT Be Pring fo gu ao set! Bocme eau a) a pn ert ele Boaid er oJ vi f ed) St ates Rivera’ =) cag | Cadet 600 eee tite Lily pocme we “SL2>.00 ay vce nz ‘et ee or ; t ct wel Wit Hortpesase Wr tee : > eis ere Att Sy 1 A255 | nee act an4p Vii dwice Ful’ Saycaiey mee ¥ at iat ys 44 rie M24 axtyod ny =! gr Ohh Neo Sat ages by di Sa Palt_L5 ah Llib) E Onl Oe | grids beast <0?) agen k oS nee wets ia. a oe ns — 1% : BES Hong Ei enAlY: FO" aco | | Paik Mal as to oa ee ek mero sie it, > Prt iad Heoock PER RpsH Sek caer & sfabre * an ' a Riese Lalegen: Fh, a py 7 : witty Sou —eAleD fu? o1-" ud As Colton has pointed out and as confirmed in these observations,: the conchs readily attack oys- ters, A conch creeps onto one valve of an oyster, again, in such a manner as to bring the outer lip of its shell directly over the bills of the oyster, ihe oyster at first closes its valves tightly, then opens them gradually, inadvertently permitting the conch to thrust its shell between the valves, The curvature of the conch shell when pressed between the oyster valves pries the valves apart; the conch then introduces its proboscis under the protection Of Jts own shell and eats its £711,” Inspection, of oysters opened by conchs in many instances reveals very little if any cetectable chipping of the bills, If a portion of the oyster valve is broken away, a conch will not attempt to pry the valves open but will introduce the proboscis directly. The ventral surface of the foot of the conch secretes a highly viscous mucus while attached to prey and this may play a part in the great effectiveness of the conch foot in retaining its hold, Magalhaes incorrectly suggests that this mucus is probably saliva, A conch once attached to a bivalve is not easily driven off, In these experiments bivalves to which conchs were adhering were moved about, and the conchs themselves were handled, with no effect on the conchs other than to cause them to bring their shells down more closely over the foot, From the point of food conservation, the method of feeding employed by conchs has much in its favor, since in small bivalves the snail foot almost entirely envelopes the bivalve so that none of the flesh is lost and potential poa- chers are kept away, In the case of larger bivalves, although the foot does not entirely envelope the animal, the conch's shell is wedged between the valves thus affording considerable protection against raids by other animals, Of all shellfish, the quahaug-like bivalves offer the greatest resistance to the predation of conchs, and yet these are also readily opened and consumed, It is in the penetration of the quahaug that the conch displays best its highly specialized mechanical method of opening shellfish, The conch mounts the quahaug and holds it, as Colton express- ed it, “an“tire hollow tor “2ts=foot™, so orrented Chae the bills of the quahaug lie directly under the outter lip of the conch shell, Then the conch, by very slowly and strongly contracting the columellar muscle, brings the margin of its own shell to bear on the slight de- pression present between the junction of the two qua-~ heug valves, and presses against the edge of the qua- haug vaive farthest from it, Such pressure is suf-" ficient to chip a portion of the quahaug valve away. The conch then slowly relaxes its columellar muscle and draws its shell margin back from the bills of the quahaug. This slow chipping away of the quahaug bills continues until an opening of sufficient size is made to permit the conch to wedge its shell margin (-88-) — , (St ewan: oe dy 21 / - a . a. he ie fy Dy aed we, r a5 _ ” Shas - 45 ¥ rey x ACT LY Ld? eh 5 ea Gk ar } 4 , > > + vw a J i Py f 7 r - - om | se, ‘ i ' oy 7 s i ‘ ” 7) fe 4° S j : Law é ae me i : (* . “s 4 j a Ree 6d Gpaw' e ih: Lpgon rir iA wae t ov’ (a, GDM aMe tlt werara. €2 ie osc re i) ee mi pli, = = #r0te9 “ee ye Teas na aa”y i) ae tg f: Sines a iw 70 ce ev! 2 ion ri Me riRy: Sis oat &. ig wd par Ser napievi tert Sogeinion pf ec ¥ du toTy 4 7 70 8 VES of? 2 qantas exit os] jan): ig teal &t Tite esa” " Oye to Gtre! wi! + “Ghd soolesre gio this: on = . om) 2 ov eb Geahe s € i “9 Gnbreevem viseret ' o> a ; ay a PIERO OE "Fos? & 346 od wire efor th «2 f tivele emey ud Ameo e2t? che phe Gf Verntasec negEve Tg tate Nae Sl Heyohe ty, sept Bc Leie? err ave 2 wie @uliS-+yositenyp od! .¢ ery edd 2 poche me eis ks a5 ‘ » (Mes Wiade gc treaips ‘ Gis MZio} Eo ,t? ails: | qi. NH Gtro lew od yt 64, a6, SiLid nanos) ad? Eitsnos ei snot; SUSE) To Riniae ao Jette role ravine gem oS LIE s0ct Fomeyest 6vii) Hie eXaMe Otley, yoethu gubh Be coktto) # sido = ‘a i. ur a | ‘Siete Wllovinfon st aaxaine Yiwelé sgn’ tues of to afild a sont Bom ai ; . Gele Jimi 402% ; « - 7 jas 4 * riea .* ‘ghey «: Thiele haere "7 ; aa ~o tube "0.8 ere Mrip ad! Ye vee wisagins we ats regi. na. £3 at teen CE a I between the quahaug valves. Warren (1916) recorded a rate of chipping of 6 times per minute, During this chipping attack the conch occasionally ceases its Slow hammering to check the extent of damage inflicted: the rim of the anterior portion of the foot, held just under the bill of the valve to which the conch is at- tached, is brought over the damaged area and numerous tiny lobe-like projections of this rim are passed back and forth over the erroded shell as if in examination, If the pressure from the conch is severe enough to crack off a large opening, as often happens, or if one or both of the quahaug valves crack from the pressure exerted by the quahaug in an attempt to keep its valves closed, as occasionally happens, the conch makes no attempt to wedge its shell between the valves, How- ever, more commonly it takes repeated chipping to ex- pose a small opening, The conch attempts to wedge its Shell between the valves as soon as an opening suf- ficiently large to permit penetration is chipped, Some victims, for example, showed chipped holes only 0,197 inch in width, The bluntness of the conch shell margin also determines the size of hole necessary for penetra- tion of the conch shell; and this bluntness varies from time to time as considerable wear of the conch shell takes piace during attack, The conch apparently adds new shell during resting periods at which time it generally remains buried in the bottom, Such rest periods have extended as long as 16 days in aquaria, Thus the conspicuous indented nature of the lines of shell growth along the- body whorl of the conch shell are explained on the basis of the periodic erosion which occurs during attacks, It happens in some in- stances that the chipping of the quahaug valves re- sults not in the formation of an opening but in the smoothing off of the quahaug bill, particularly of the valve edge farthest from the conch, and/or in the formation of an opening which is too small to permit wedging. In such cases the conch eventually deserts the quahaug, In one such instance a conch worked al- ternately between two quahaugs for 7 days without pene- trating either, and finally deserted them, Out of 37 quahaugs which were placed with one large conch in one experiment, 15 quahaugs were opened and 10 were attack- ed but could not be opened, In only 2 cases in these observations did a quahaug victim show two areas of attack, in which apparently the first attack failed, and then the conch returned on a subsequent day ina second attack which was successful, In 31 quahaugs opened in one series of observations by conchs it was noted that 52% of the sites of attack were located posteriorly over the siphons, 27% over the midventral region, and 21% over the anterior por- tion of the quahaug opposite the siphon, It is sug- gested that the selection of the sites of attack may be influenced by the flow from the excurrent siphon of the quahaug, (-89-) A ST ee a 227s ra) ha ’ c.« h ri) — ‘ *» . 7 . I » =» . “Vv & os : -iatny) wer. ap — ; “a ° > | alge ¢ iy? ) > ype — - * Sy é ! Ps | t _ § Ate an } b: , eee) é i ; aio? tit: Dived f = ahs : 7 7 - a Le ‘“! 7, ; Te ‘ins f %.? 4a - 7 at f Sty’ sh GoT4 <4 , ‘ Oly _— 8 chev o ie? cs, Pay ny | ' F : i n 4 j 7 ss 1 ? Ae Ie THs pet maine ® [™ L f - § SoCliw yi . a Py h rah h Fae) - P 5) a Pv (in i SplhnS diem ot. heat. de eee Ba5c7 gud’ wil ” We st! arash ot EDAD Pug hg 4 ea 4 2) | : 7 ’ 1B Si0 i. aw 7? tte Vad a » Pra i 4 ce. J)/ be lift iT < ve : 7 a: J ¢ iv od ~ & ) aa. KANG 992 >: ® i boc ief G8 wil Wa ry It was reported to me by members of the crew of the "Quinnipiac" during a trip on Peconic Bay, Long Island, that in the course of examining the mterial pumped off the bay bottoms and passed down the con- veyer they had observed two cases in which large conchs Still affixed to quahaugs and with proboscides extend- ed into the quahaugs also had the operculum wedged between the quahaug valves, The use of the operculum in this way has not been observed during these experi- ments; it may well be a further means of facilitating penetration, It was interesting to note that although shell- fish are helpless against conchs, small sea anemonies on these shellfish are not as ready victims: one oys- ter on which a conch was creeping held a small sea anemone, As the foot came close to the anemone that portion of the foot nearest the coelenterate was sud~ denly withdrawn, The conch approached several times, each time retracting, Eventually it passed over the anemone, carefully elevating that portion of the foot over the anemone, Apparently, the nematocysts shot out by the anemone were effective defense, Colton in his brief description of how quahaugs are opened by ccnchs, wrote that there are three ways in which penetration is effected: "First, it may flatten out its proboscis so that it will ¢o throug the crack; secondly, it may pour in a secretion be- tween the valves which kills the clam; and thirdly, it may wedge its shell between the valves." The first and third ways mentioned by Colton agree with the observations herein reported; however, there is no evidence (nor did Colton present any) substantia- ting his statement that the conch may pour a secre- tion into the prey to kill it, nor Magalhaes'? sug-~ gestion that the conch may initiate digestion ex- ternally, On the contrary, there is evidence against such a statement: in some of the attacked but unopen- ed quahaugs, holes as large as 0,4 x 0,47 inch were left and yet apparently no secretion had been poured into the quahaugs since they were vigorous healthy animals weeks later, Some observers believe that the valves of shellfish are pulled apart by suction of the foot, However, Magalhaes has shown that a pull of + to 6 pounds is sufficient to dislodge a conch firmiy attached to a surface, whereas Reese (1942) has estimated that a force of 23 to 26 pounds is necessary to force open a quahaug. Extent _of Conch Predation on Shellfish in y. in the first feeding experiment all 6 conchs were placed in an aquarium of slate botton, 23) x 12 iaches*s jcoverca wich about /2 einen or sand, in the vresence of numerous quahaugs and edi-~ ble mussels, ani a few salt oysters, razor clams and soft clams, The temperature of the water re- mained in the vicinity of 65°F, and the salinity, 20-) 28°/oo, In the course of 23 days the following shell- fish were opened and consumed: Edible mussels (Mytilus edulis), 0.6-1.6 inches Long 69 Quahaugs (Venus mercenaria), 0, 8-2 7. Clams (Mya — Foti 3 Razor Clam (Ensis), 2 inches long ele : 50 Shellfish consumed per conch per week ...c.ccccces a) Conspicuous here is the fact that between the qua- haugs and the mussels which were present in large num- bers, the conchs made greater inroads on the mussels, In a second experiment the 5 smaller conchs were placed in the same aquarium with an excess of oysters of various sizes, Ina period of 99 days from December 29th to April 7th these conchs opened and consumed the following Ostrea virginica: Ostrea Size Range, - Longest Dimension Number Consumed Of=0. 7 inene SSR el. | ane See wr Pe 28 OF 8-151 inch wae 5 Smite ere ; Oleh “OleOroe De on g Pre=sad. inch eo 16) 6. @, @ “@.. "6 @. (6, (@% 16) em (ey a.emne 22 59 Or one oyster consumed per conch every 8 days. In a third experiment the same 5 smaller conchs were placed in the same aquarium with an excess of oys- ters-of Various) S6izes.= Ineay periods Grom, Aprad Graco May 8th for the 5 smaller conchs, and April 25th to May 8th when the larger conch was added to the tank, or a total of 163 conch days, these conchs opened and con- e@ sumed the following Ostrea virginica: O:4-0:7 inch, Dio O00) 5 Oo OF oO dG Gt: 0 3c 338) 0,8-1.1 inch Oooo oO ooo oO oa" 6 & GO 18 1,2-2,6 inch © @) Fo et ve ne NetPhelt om Kouze one 12 63 Number of oysters consumed per conch per week 2,7 The threefold increase in consumption of oysters in the second period may be attributed to the increase in the temperature of the water, In the first oyster Speen above the temperature of the water remained between 64: and 68°F,, whereas in the second experiment the temperature remained between 68 and 75°F., or ene In a fourth and final experiment it was hoped to check the extent of predation of quahaugs that were permitted to bury in sand, since in the previous ex- periments the shellfish were lying directly on the bottom, exposed to the conchs, The largest conch (Busycon carica) was placed alone in an aquarium with slate bottom 2 x 1 feet in area covered with appr oxi- mately 2,5 inches of beach sand, Thirty-seven quahaugs C9i-) Ia dane a —- a ec ia Da SR a la Ta FSP TT ES SN TT ehloey “griwaiiel adit ayah 2.4 . OS from f 3 i tla l wal seriock FL ais. gl 4 ee aldrha Ww S ; it i i) cies) ic ' f ue, nel” i j i ' — yy WSs wats cheetos a <3 H cE I witet RD A moaned Phd? tow? az m2 ma) GWiel nl JaGiois rae ’ E { rieraim Pcs fo mrt : 3 ay Tt toneo Téifome § of 4 ‘ ve Fue t iS & tbe Py bs +} i ’ te cs .*(G.) ap - Sry Trdg py! : i 7 OO 7194 el oe Ci : iD ¥ j I te 4 T nt j tiie WE art LL7 ax. b> OY eb bel a BS Te ’ ¢ »”@ «a a “’ . $ » «~~ Ps » igs 4 5) Q * © « Po a eee . 7 a Vie C, Coa =" had ° » s . ‘ r e r] . . « uti Ck SL wip? D epeye doi taq = 17 « “a RGO =O ico soliegae sure off Jo ni brs + nt a Baa io he at? er) teick : t [4 @7a4 - A Se 4 j > ota2 y 4 at on 4 — ‘. = oy } ; Rome lg 5 = ton Vad ned t £,f£-3,9 | as 0, 5-a.£ é TO secu @ 5 _ i+ ry wh | wi Td ovis nt 2ofenwot wif at V2G. gach teqxs 2 fm pow eog cane mage 3S Stun i12ve a —_—- ~~ 4 J wa em reint a] ~' atvss 4 ah on ta beosl¢ tev Cnpizaa os ‘59923 ™m at toot £2 5 gOe: rae en ian phieed eo sqgent a “C aa A eos 7 : . 7 at el hd ef” 1 2 : ‘ PF * } > y oe ° i i b — eee ae ad U 1 t ms tetind ¢ a wer > Pini rio 2 ett ime “wie «Ss! ry! ets 4 H \ sv ¢ y ef ah) ra 1 {/ A ~ at 4 ate r Py > ft aM f » foe ? Lg i ‘ ch ; . ; eg oes re0ot gel § 5 z » aS > } aae eu clOnt @svov lL. e'Nes Kc) Gris New pre 7 Slat Lantos got) @ he Y sheer uP ae 2426 (re rae ¢, egies te v sna : + Pett of: a SYA a9 ‘ : ee. we 7 7 MPI 2 9EO4: UZ save : ateraD oaitew et? Bo a) evetoisy wks aire e Ivo ti aah Above Soave avs toes et nr - z | mm % vieta [otlatiom MPL A peoatiegem Wee 28 oooreN urea; we %& t vi Mt af 24 tank 2” /* eforaiay TOXIC EFFECTS OF OIL MIXED WITH CARBONIZED SAND ON AQUATIC ANIMAIS, - -by- - Walter A, Chipman,Jr., and Paul S. Galtsoff U, S. Fish and Wildlife Service, a a ke 3 2k 2k (A paper presented at the Annual Meeting of the Nation-~ al Shelilfisheries Association at’ Old Point Comfort, Virginia, on June 9, 1949.) 3k 3 2k Oil pollution of inshore coastal waters is a prob- lem of major importance for the conservation of our quatic resources, Aside from being destructive to aquatic animals and plants, oil and other organic liquids floating on the water area great nuisance to such recreational activities as boating and bathing and create a serious fire hazard, especially around piers and other structures built of creosoted wood, After a damaging fire at the Norfolk Naval Ship- yard, resulting from the accidental ignition of oil floating on the water, the Chemical Laboratory of the shipyard undertook a comprehensive study of the exist- ing methods of removal of oil slicks and began a search for better ones, The experimenters of the Navy found that a carbonized sand can be prepared simply and cheaply by roasting creosote and sand in a specially designed kiln and that this has remarkably good organo- philic and hydrophobic qualities, The sand, with its carbon coating, is sprayed on the surface of an oil slick, Coming in centact with oil, the carbon coating forms a stable bond with the oi1, The mixture may then be readily removed, If on the surface of the water, the combined sand and oil may be sunk by a stream of water under pressure or by some other method of agitation, The bonding of the oil and carbon sur- face of the sand is permanent and an oil slick thus treated remains anchored on the bottom, A popular account and graphic story of this new way of removal of oil slicks appeared in "Life" (1947, Vol. 23, No, 19), The caption to one of the photographs accompanying this article stated that the submerged sludge "is lethal to most marine life", Since there was no corroborative evidence of the toxicity of oil bound by carbonized sand, the United States Navy, through its Bureau of Ships, asked the cooperaticn Ol the Fish and Wildlife Service in a study of the prob- lem, The present report summrizes the results of the experiments conducted in compliance with this requesc. Oils discharged into coastal waters do not remain floating indefinitely, They are absorbed by particu- late matter suspended in the water. Agitation Ole eae water by currents and wave action helps tne settling of the oil=saturated material on the bottom, but the oil slick is not securely fixed and may be carried to (02~) w. a * f y rt , Gi . iM ’ zt | - 7 tc P } Sani : Ii . [ bi b. fata teV i i = “ f , j r if ii v7 . 9 - f rt ] ! t ai f > 4 ‘ } ‘ ) ey = i” ] i. ; : f 4 L 63 -F . : Khe Pirie a We Seid es: v : ' ’ 4 a be § gel wi F hg a ih pi a Hos = 4 Les Mm i De i j { ( iy.” pee ary Mose Foat ) y! Ho. * Z 4) Wi? @ i Lovey / “ vee «ete » ta G® Gterit ’ + J a? C y >. = 7 ; to) go 1g, tete pod igi a th ) {senate 5 44a : = . Peau i¢@* S rae i a) | > = = t , nn 4 iy “ 2 own end . { folie } 3 ; fe? > ; re ~J i | . Tel + 44. oe UT Bis oi Yon tig ba ff we .aePAw wo w ie wy ¢? ES b J ' 30 = Ste z ¥ f aaa’ uy -% $2 oF 7. id rine 16 bd F = E 12 <€ t ~ oy 2 Ss ¥ ,wosreu ie +n 5 1 yf faseo > ea 4 eo ; - + 2 far 3 a veoh | ane eukor : ti Lever te yew ) te f- : . '. a poleaee : om ,=5 Foe Seer) we ee Sieth SC) ST VGetop Io, aapeegosodg: + Bey = Gs is ’ Satara be utouds ¥gt § » af 5% z ; ae ; 90.4: te (ORK! te weet not tos a? bd. Vy os if serems oe BREW hb i FP cslpagy o ‘ORS ou, J Maps Savoy of P70 d4/ ott Atty eadalignes 2: bed eur : 7 Oy 4 a += ~ 26 POs 4 aS sJitad = MY ob erotev Latagon ont boytatos ve beirde oie yort .etesinete eS oaetke lak 4 wataw ait mt be ieesoee SOU. Hy 5 fou aly: » erry Ua y ere ; aOTIGd Of oo Lelieseg Dadauc 700 ve hy tonsa, distant places, This characteristic behavior and its importance in aquatic life has been emphasized by Nelson (1925) and Gowanloch (1925), Injury caused to ducks and other water birds by oi1 floating on the water is well-known, since many instances have been recorded of the finding of oil-smeared birds unabile to fly (Lincoln, 1936; Adam, 1936). Likewise sedentary animals living within the tidal zone and coming in direct contact with oil may be destroyed, The toxicity of oil in sea water, due to water soluble substances extracted from oil has been demonstrated many times experimentally using fishes and marine invertebrates, (Seydel, 1913; Nelson, 1925; Roberts, 1926; Gardiner, 1927; Ministry of Transport and the Ministry of Argi- culture and Fisheries, Joint Committee on Damages to Fisheries, 1930; Gowanloch, 1934; Galtsoff et al., 1935; Galtsoff, 1936; Veselow, 1948; and others), ba Since there is convincing evidence of the leaching out of toxic substances from oils pre- sent in sea water, it is desirable to ascertain whether the combination of oil with carbonized sand would alter this action, The combination may either lessen the toxicity of the oil, or it may increase it by bringing the poisonous oil closer to the bottom-dwelling forms, permanently anchoring it there, and allowing a slow and con- tinued extraction. For our study we selected for experimen- tal animals such forms that would normally live attached to submerged objects, or on the bottom in estuaries and harbors where this type of pollu- tion is most, apt =to soceur, *Werchosic@in=par ecu animals of known economic importance, but also in- cluded others which aptly land themselves to the experimental procedures desired, We used the follow- ing organisms: the hydrosoan Tubularia crocea, which grows attached to pilings and docks; the barnacle a very common form growing abundantly on rocks and structures near low tide mark; the embryos of the dwelling fishes in harbors and bays which attach- es its large eggs to wood, rocks, and other sub- merged Yobyiec ts; “the hard “shel? clam Venus mercenaria, which inhabits the mud flats; and tne oyster Ostrea virginica, found on rocks and on the bottom in all coastal waters, The oils tested were supplied by the Navy, these included crude oil, Navy Grade Special Fuel Oil, lubricating oil (SAE 20), and Diesel oil, (-94-) >= ass we) : Of Thre fo ra * peal y Snsteeh YD M ‘ | aD ¥ Ce B opru Mroqor _ : . ) doetiawot tee (28er) noekott. 7 ‘J P | oe Se ay ir he OF) Occitier earl nt - . | 1 SA sw aO TY tte ed : : 7 - ola Eni gee vt Vou OFnr weniasantl yas .. ; ! ge fi f i I eg roe) tid | Cor mou a=flo H - : s - fiw oar, fm « de a? Q . q io ait y vt ies o% Alte _ : » (CECE iL ‘“ ? _ » a OO: St . Betis ytd mg Paes ant it et tem Llo a , - OF, apih raveyv nae? Eis 2 ts Laggs} er ? ‘ Py ° oy i, a vi 4k Pigs fj - , ee ra Aer: arity Prey: Cit a8 oe ‘ ‘eS, bl rk al tA OS SaVELID ty ai aa 7an ae ‘ o¢ : 7 yt aa ? v a. 9 ate =" _' Lie wv Ps ‘ : =r 5 oe eT on se a4 (ih te ae St aay Pp’. P ; ‘=i Got A464) 7 ¥ (PE: =! aia Lie, Sisto pa f > a an poe 1 eis hs it Pra if * r. ra ‘pat err ag : we ( Seesy (CECt 4 tIAn Es aren - , et petite ue >be 2: 1) Res ich to BoM len oF stoasiges «i v= pwitoW pon mt Fe ate Sige Giv Sip 390 sttfatiecs eft) duite a re oo pili an Ev bz ? ‘ts 6loow- Sy : i: ony To yeielsa? > Jereel vette 3 fle euccg MoT SUF wihanied Us St ateeeent yn 3 ‘ s h : 4b , =a Tato aif TNE amit mill eub-eeriodg wiv of swae “mh Sct wt S piswise ine ,6-5,0. 7) gtitods 4 -@¢ @= ‘MOLT ORTI RO Beosmat daters per hour a toxic effect becomes apparent after 48 hours if 5 ml. or more of oil mixed with sand are placed in the immediate vicinity of Tubularia in a 2=1iter jar. The results comparing different oils show that lubricating oil was least toxic, while crude oil ap= peared to be the most toxic,;.. The toxicity of the crude oil apparently resulted from something leached from the oil by water, for extracts were found to be toxic to Eubularia, EXPERIMENTS WITH BARNACIES, Balanus balancides(Ag,) Adult barnacles can be conveniently used in toxicological tests, The barnacles can be easily arranged in a desired position in the experimental set-up, The erfect of a toxic substance can be studied by observing and timing the sweeping of their cirri. In running sea water or in containers in which the water is renewed daily, they remain active and apparently in good condition in the laboratory ioe many days and weeks, The test performed clearly demonstrated the toxic effect of crude oil and sand mixtures placed in the immediate vicinity of barnacles, A slowing of the cirri (~95-) ‘ Ae i Twa. 2] decays ad van i = ri = 7 Re he j } ( t 19 y, 1 i * Bee ene) e° 7 PRRST 4) wh ae a¢. ) we wr & peu i i ¢ ye ‘ it . ae of 4 fh ay ‘ Poe ry a mal j y," om Pye ee ARIUS 2 hha E i (‘he eres + te mde bas i i oh ay ¢ | pal , te wes 5 ° ’ - ~ : y ¢ ae 4 ib : a4 ar? A iq Thee LAs wee ae | “TOS Kiya: ort r aie id LO aet a. oar ee. CL opel Bie’ ‘ PY Pan rae See TATA Chelate Bs Suen of Ta ae ioe) / ey My bene? ry tae ey yee 7 ; PY te Me SHreeee thie it ntont, aniges MT tie id : FR rs i: ee 2 ie ye" AAR cn | . i re j J ' 7 : j a : @ fe : j ia AA be F abo os m oy ban fase oUt gi Lak ENS bik 3n zr toh a iv ba com | 0 BiG © 4s Ane «@ r yy any i oe byl ) ae hs » ey 1 aniniotet hie Ww ae AS ban a | ti ine Sse w® yn lted avi ar , As ay 6 iy s LAgr ri 4¢t ore 4 uty tavtad RSE giathrane Yesew coe sity Ak de al Sm £ite 7 hitey io “silt ox ani D wees < a Kw Ae Faeety *t 3 “ihe MOD a : id rl ra é [ os K > - 2 il ul rey lie beecgediivc they joule Lbs > Selby. A “@ 4 ‘ . a wre yh i ‘ q = ; y ¥iens <—\- LEP | mS 2 igi : Biti ae ¢, of Porky ad =« ‘ ' . oi } Mii is = 2) WOT) @ I< a; Fn ar - 4 i} I PE bel * Ab r »% +l f4a% tw ulcod A one ‘ “ | etiy I tT eT) .in = 4 O oT, we ’ y £ g aa 2a) ¥ kegs YT eIesE Pr ¢ is : > . Clio soe ED Stha raw .aecueet et} ease BIT 1 ots l 5 : ms 22 lx97 AT: a kyo? r dea i 4 Oya. F ¢ toa ae) a Vi2 ane |d S OO!) 6sgraed aett Isdne=?t4qx0 i> ht nope twee : 9 ’ (30 @& oJ Dit vf pirtavaws ath onitgut? te “eViton alene tartt fw 107 Lat Aen Sk .calsansad 7 7 i i. een Vane O" » Fignee we Tst Hs CL Poke “litte loyuses ef apo oike? a W s4o% ted! Oadites AQ6 "i 16 402 aw ne ' vr¢ oily Dawns et Vv inteveds! i on7 mt ins tite arr aja Et eto o eftaols bewcansog seh pret Gy See Drwask ite ; > ‘oe i oer an’ = spa? ee 4 \y i , eri "es tow rior) Surpteees 22 olmor puryrrege. Yo} 7 ade ul “A nfo ee nD 9. was observed within 6 hours in the weakest concentra- tion tried, 1:50, Poisoning was progressive and com- plete death of 80 to 90% of the barnacles took place Within 70 hours, EXPERIMENTS WITH TOADFISH EMBRYOS, Opsanus tau Linn, Toadfish embryos present excellent material for bioassay; they are large, fairly transparent, and are attached by egg membranes to pieces of wood, stone, shells, and similar objects, Normally they are quite active in the laboratory jars and the beating of their hearts and the circulation of blood can be easily observed with adequate illumination and suitable op- tical equipment, Crude oil mixed with carbonized sand was found to be quite toxic, Even the lowest concentration of 1:200 was sufficiently toxic to kill all the embryos in il days, The mortality of embryos in’water with greater quantities of oil was more rapid, If the log of the survival time is plotted against the log of concentration, the toxicity curve approximate a Straight line, The lincar relationship obtained by such plotting can be approximately represented by a general equation of type_y = a x° and the constants : a and c may be computed from the empirical data, The relative toxicity of the different oils mixed with carbonized sand was ascertained, Crude oil added in the ratio of 1:40 killed three out of five test embrvos within 474 hours, Toxicity of Diesel oil was noticeable within 52 hours in the concentration of 1:20, while lubricating oil was ineffective even in the concentration or 1:10 (50 hours). EXPERIMENTS WITH HARD SHELL CLAMS, Venus mercenaria Linn, The hard shell clam, chosen for experiments because of its economic value, is frequently found in polluted bottoms of harbors and bays, Because of their ability to close themselves within their shell, clams, like oysters, are capable of slewing down their activities to a’ low minimum for rather protracted periods of time, In this way they may reduce the immediate effect of unfavorable condi- tions: In the one experiment performed, the sea water supply to the clams flowed at the rate of 21 liters per hour through containers containing 20 mi, Of sanvoi” orean~ oll “and “sand mixture, None of the clams died during the 123 days of the test in the sea water containing crude oil, fuel ol), Diesel ol, or Jubricating oit or mixtures of these oils with carbonized sand, There was no evi- dence of their weakening, (=6—)) a ~—— ET ee ee CO Te EIS SHREYA TS ES RELL IL SIE a EN I LET TT Oe Te eT PE ee Se RE ene s a _ ’ c : : ‘ q . Jo 264W Vs Tye / | yi > we nor ; : i] ite mf ' 3 ea) mataek aaa seat — | asend OY SLUIE i] )Piperes > GOW hie 2 meee 4 acest feos cenusk te a EO a 0 + aot: ¥. Sa', = w 7 am pf = Se € = ¥ @ ui Saletan ic abit er ae oa : J i i " halle Pr fae ‘tes ‘xputte Yo fleapaad ‘tetettog ri | peer ta sini & SAFI ~stats _fior Petites tod} oa 3 “Soiten Sod otic a _ STs.) Bao eno wl. a, At at etyqus te: writs 1 ad 0c 33 xs ie a wile 2 ht 2 si/tal bepp' amar. A Rade te a! ¥w7ete Yo iso ot hxehet 0 4 atont Ae, be atat 4@ iE Rang! a EXPERIMENTS WITH OYSTERS, Ostrea virginica gm. Because of its great economic importance, the oyster has been studied more than most marine inverte- brates, Consequently its physiology, habits, and life history are better known than other lamellibranchs, Living attached to rocks or lying on the bottom it is frequently affected by oil wastes discharged into waters, Having no means of moving from unfavorable environments, © the oyster protects itself by tightly closing its valves, If the inimical condition persists, the oyster is even- tually damaged or killed, Tests of the toxicity to oysters were made of standing water to which were added crude oil in a ; dilution of 1:500 and Diesel oil in strengths of 1:200, and similar strengths in which the oils were sunk to the bottom mixed with carbonized sand, In the test with Dissel oil the first death occurred on the third day with an oil layer on the surface, and on the fourth day in the aquarium with the oil and sand mixture, By the end of the test on the 13th day, the mortality was 67 per cent in the test with oil on the surface against 25 per cent with the oil treated with carbonized sand, There was no mortality among the control oysters, Ex- periments with crude’oil added in the ratio of 1:500 gave similar results, In these first death was ob- served in the ninth day and the mortality was less pro- nounced, due probably to the small quantity of oil used, In experiments with oysters kept in large tanks of running sea water and exposed to a mixture of crude oil and carbonized sand, no toxicity was observed in 35 days of the test, It was found that 500 mi, onset introduced into a water system running at the rate of 180 liters per hour and anchored by carbonized sand were insufficient to cause mortality or to inhibit the growth of the shells of adult oysters, The maintenance of a steady fllow of water through the gills of an oyster is essential for its feeding and respiration, The measurement of the rate of filtration of water is a very sensitive means of study- ing the effect of changes in the environment of the oyster, for the organism rapidly reacts to the pre- sence of toxic substances which may be introduced into natural waters, Methods are available at present for measuring the efficiency of the ciliated mechanism concerned with pumping alone or for obtaini.g the over- all picture cf the function of the entire "urping sys-= tem involving also the mantle and shell, “Zxperiments were performed with each method, the former known as the carmine--cone technique and the latter the apron method (see Galtsoff, et.al.,, 1947). It is impossible in this short paper to describe in detail the numerous experiments performed and the results observed using the various oils, these oils oT) tas, voli bith | eetiwe Wid TEED eit oats Fe 4 Bae Tia BS 14 tl cee c Pees on? Gta GePaoe poly so 6F “HOT yas | oe uv apt Rae ey. She pat iy a Peet EDS 8 rittd ‘wai eA? art ves ep bck ‘5 ry ths at a7) GVsioe we : =ioS is uted ¢ wr hew be cl Dot)» eight 7 a gost gidee T* 40h - Liye ity hey & 7 NLPige? Va tert? ro ieaty teats gee at eit ,walaceq Gol? iiding Lngeerak Get Za Boe £55 °474,,C). Yosviset? ai “> womet pa Sil 8 Dente et iene H ‘Bj ie eer eas wie iW @. «sow Nehigg = a See ae acs "52 fies kt! Sas i cto frie? CPt, ay ett lim ay Mee Ge! ot y Tht Dike SNe Hl i the ert 6fty Tk & ijt ed on ; oa ae on ee OCs Gh Scat wit Io: Gi) Oe ; 3 elt eo i) miu 268 eae re .{ ab Leg ye : po lo timei? {26 ae Tso Iris Dik.) YC Say Bmra CET we Gn 60) gant oF bGGhe £55 ies iv < Fouche ee ried Mi .ctiupet qeLtebe ove Pon Vio edt ad. ct eving Tes uy WwW Eldetowm, Gub ,Aeunws ‘qed « tv Giwentviper nt : eos e Yalow wos gains ‘te i st on ,om¢ feptugdtne foe Lie ca iL ame wi) SM s¥ad te a wAcow & odat) beguhope: 2 . : biti recast oq mere, OS©- - . S255 of! Imstolttetol gcoe “a M fies oil? In: tn on : ; © 36 $s le ait - 7 +s at tif et ELite ott cf mn by —— > eyes «tT asain bpm ge chu? rT to? aah 7-3 tl 16 Pow The edt sate": : ™% aff @ efanes * Gaineagsto 7 “ot _ tel ayo: . dat te cootent od bat agoiel tien Biaoe lo sones : we apsgose 24 afdeliave ot Salvin fever?! i tay um Ns Lad eM aviond Bali ott eo aug si, aio to ¥ Oh Stritasde: hi mw Sete id tw fo I rth ivey | Sic ard to pore ee ; Hoar! ie timtz tos eftoem ed? asta. qatvie ‘ee nwtete sot oti ,badtrése to ny tw teéarts opie eml teljai ot bap s hee ‘ = set t#el olay: : othe fap any. Tcoab Oh igeg Prove a2h? x 2 oa ans cyue oi "oy «dnomideqxs $4 a Rho aeact yelho syodety ett gate ude BS ! > = 2 7 mixed with carbonized sand, and extracts of these o1iS in experiments in the physiology of oysters, We conclude from the various tests we performed that there was a realease of physiologically ac- tive substances which suppress the activity of the ciliated epithelium of the gills of the oys- ter and that the anchoring of oil by carbonized sand does not prevent this release, Sau MoM Ack Wy We found that crude oil, Diesel oil, and Navy Grade fuel oil added to sea water are toxic to the various animals normally inhabiting estu- arine environments, the more sensitive forms be- ing killed rather promptly when compared to the forms known to be more hardy, The toxicity of these oils is apparent whether ‘they are present as oil slicks on the surface of the water or are held on the bottom bound to carbonized sand, This toxicity results from material leached out of the oil by water, The oyster responds to relatively weak concentrations of the toxic materials leach- ed from oil by a marked reduction in the amount of water filtered for respiration and feeding and a decrease in the number of hours open, There is definite advantage in the use of carbonized sand in treating oil slicks for its localizes the oil pollution, prevents the spread of oil over the surface of water, and submerges and permanently anchors the oil near the source of pollution, In view of the fact that bottoms of harbors and bays near inductrial ports are grossly polluted and non-productive, the sinking of oi1 in these localities will not increase the damages to the fisheries, Dusting with carbonized sand is a highly efficient method of removal of oil from the sur- face of the water, It is useful around docks and piers to combat fire hazards and also has distinct advantage in preventing the movement of oil slicks to productive areas where great injury to sea food resources may occur, We hope that the method will be adapted in some way to have more general use in combatting oil pollution in coastal waters, (-93-) LITERATURE CITED ADAM, N. K,. : 1936, The pollution of the sea and shore by oil, 22 pp. London; Harrison and Sons, Ltd, GALTISOFF, P.S. 1936. "proc, North American Wildlife Conferences, Feb, Bei 1936, Ppp. 550-555. GALTSOPE, VP sS.50PRETEERCH, He Bic SME eR Os andys © KOEHRING, Mie Os oy. Bail U. s, Bur , Fish, 48:142:210, GALTSOBM) (Peo (CHUPMAN 5) dirs aWiguve ENGLE, J.B: and CALDERWOOD, lal N. 194-7, Fish, Bull yor the Fish and Wildlife "Service 51:59: Ten f GARDINER, A. C. nO272 Fish, Invest, oY aweat Britain) Series ih, Vou erel. No, 2, 14 pp- CORANLOCH, J. : 1934, "11th Biennial Reet. La, Dept, Conserv. Pp. 67- 127. 1935, Trans, Amer, Fish, Soc, 65:293-296, TAINCOLN kee Cr 7 1936, Proc, No, American Wildlife Conf. Feb, 3-7, MINISTRY OF TRANSPORT AND MINISTRY OF AGRICULTURE AND FISHERIES, 1930. Detailed Biological and Chemical Reports on Tars Used for Road Surfacing, 171 pp., London, NELSON, T. C., quoted by LANE, F. W.: BAUER, ADs FISHER, HH ece ND HARDING, Pee 1925, Rept, of U; S, Comm. of Fish, for 1925, Appendix V, SEYDEL, EH. ; 1913, Mitteilungen d, Fischerei - Vereins fur dic Provins, Bradenburg, 5, No, 3\0 pp. 26-28 VESELOV, E.A. 1948,” Rybnoe Khoziaistvo 12:21-22 Go2>) ei ~ Di * Pi j a Ahoy t ; a ma yl mY) 7 _ ¥ ; ; * fs hoe a a Ms a ont Cok aee 7 ‘ ) Mea Tair hf } - a 2 - Th eS nRATS Bc eo 2 ove ’ ¥ - SLAG , HERE f SAT Ie mut hy 4) 2 AD vd SLI AD I h f i ( : STAs ae MBL/WHOI MN WH ] | | | | a : m Ws» s J vd ay ey / i B sae = sy ebay cB 4 \ » >