SEASONAL VARIATIONS in TOXICITY of BUTTER CLAMS from SELECTED ALASKA BEACHES I Marine Biological L-;- •■ ,:i LIBRARY OCT 2 31950 WOODS HOLE, MASS. SPECIAL SCIENTIFIC REPORT: FISHERIES No. 53 UNITED STATES DEPARTMENT OF THE INTERIOR FISH AND WILDLIFE SERVICE Ibcplanatory Kot© The serias embodies results of inTestigatioiiB, xiraally of restrictad seeps, iateaded to aid or dire^st management or ■a.tilisatioa. practicss and as guides for almiaistrative cr IsgislatiYe action.. It is issued in limited qTsantities for the offic'la3. use of Jsdjeral, State or cooperating agencies and in processed form for eeoaomy and to avoid delaj in pablication.. United St-ates Department of the Intarior Oscar Ip Ciiapman, Secretary Fisli and Wildlife Serwice Albert M. Day, Directed Special Scientific. Sepcr*. =■ Pisheries No. 53 SEASOUAL YAEIATIONS IN TOXICITY OF BUTTER CLAMS PSOM SELBGTED ALASKA BEACHES By J&im S. Chasnibers a^d Harris W, Magnassoa * Chemist, Branch of Commercial Fisheries ** Chemist, Branch of Commercial Fisheries, formerly Fishery- Products Laboratory , Ketchikan, Alaska, now Fishery Technological Laboratory, Boston, Massachusetts Washingtoa, D. C, August 1950 Introduction The iRV3S3tigai;ion of paralytic sbsllfish poison in the clams of Sou'Hheastera Alaska condacted hy the Jish&rj Products LahoratoTy, Zet'Shikan,!,' was diTidsd into threa main projects. The one with which this t^por'!-. is con^tseraed '.b the geographical and seasonal distrihution of th(9 taxltL in Vattes' clams, Saridonriis giganta'^is. The other two projects, the study of toxin reduction "by processing methods and the study of sampling aaid testing methods, are to he reported in separate papers. Batter clams aae the most important ■scmmercial cleun resource in Southeastern Alaska, IHherafcre, the swdies were devoted almost entirely to this species. InTestigations of an exploratory Qatu:re performed from 19*46 to 19^8 established the presence of toxin in hutter clams from many of the Southeastern Ala^ska clam prod-^cing "beaches during all seasons, ProiE May 19^ to September 19^, inclusive, a systematic monthly saTiPDling of representatiTe areas on certain eommercially exploitable clam- produsing beaches was carried out. The purposes of the survey were to determine the monthly fluct'iations in the toxicity of the clams from the different areas and the variation in tcxicity between the siphon and the body. InformatioiS. on ^-hese factors is essential for intelligent regu- r.ation of this fishery and enables the processor to eliminate a major so-oree of tox5.3. fr:*!!! the canned product. Collection of Glam Samples ^e laboratory motor vessel Be searcher, usually operated by a cr?w of three men, was tised in collecting the clam samples. Shucking of the clams and preparation of the extracts were performed aboard the boat, A wi.de knowledge of the elam beds in Southeastern Alaska, gained froas the earlier gensral survey work, made it possible to select 10 s-epresentativs .^iam beaches on which were laid out 22 plots. Nine of the ■jeaches were knows t-5 produce clams of fairlj!" high toxicity; whereas, the A-emalni-xig gzl? yielded ciams of low toxicity. Preliminary tox5.city tests o^a man^' individaal clams from a single plot showed that there was con- siderable ?a,riatiers. in toxicity between clams. Tb.ese tests further showed that resul'.ts si^ificant wit'hia plus or minus 30 percent could be obtained from a sajiiple of 25 clams. Therefore, the plots were made large enou^ to supply at least 18 samples of 25 clams each. To provide a thoroughly repre- ssiatati?© sample, not oT<^r 3 clams were taken from each hole dog, and the holes were distributed well over the entire plot. All the study plots were iatmdatsd at hi^. '^ater and comrpletely exposed only at a minus tide. The c'sllections were made, weathjer permitting, during one of the minus tide periods each month. 1/ Jointly operated by vhe Alaska fisheries Experimental Commiasion and the U. S. Pish and Wildlife Service. Ezt-racting and Testing Procgdure lEie clama were opened with a siiacking knife while they were still alive „ The shucked olaras were washed in fresh water to remove all foreign par'iicles from the tissues, and then drair;.ed. The entire siphon (neck) was severed from the Isody, and the siphons and bodies were treated separately. These were minced using a hand operated mea's chopper. The ground material was mixed ihoroughly, and to 100 grams of the minced material was added 100 milliliters of 0„I2 N hydrochloric acid (l part concentrated hydrochloric acid to 99 parts distilled water). This mixture was boiled for 5 minutes while baing stirred continuously. After cooling, the mixture was brought to its original volume by the addition of distilled water. A portion of the final mixture was bottled and stored in the ice box of the vessel until the boat returned to Zetchikan, At the laboratory the pH of the extract was determined with a pH meter, and, when necessary, it was adjusted to a range of pH 4.0 to 4.5 by adding 5 N hydroch].oric acid or 0.1 H sodium hydroxide. The extract was centrifuged, and the supernatant liquid was placed in vials and stored at 0° to 3^ 0, until tests were performed. The extracts were tested on white mice which weighed between 15 aaid 25 grams. The mice, obtained from a supplier in California, were a mixture of two strains. Thsy were shipped air espress and arrived at the laboratory in good eonditioao The extracts were injected intraperitoneally by means of a two milliliter insulin syringe. The smallest practicable needle (27 gauge) was used to redu'je leakage from the puncture. The voliane of extract injected into each ro.ouse was varied according to the wei^t of the mouse, One^twentieth of a milliliter of the extract - or diluted extract - for each gram of live weight was used» This procedure was found to be more satis- factoiy than the injection of a standard amount of extract and the ajjplication of a correction factor based on the weight of the mouse. The lethal time was computed, in seconds, from the time that one- half of the volume of extract had been injected until the mouse took its final normal, rhythmic breath. This time of death, in almost every case, was accoarpanied by a complete relaxation of the body, followed by a series of reflex motions varying in intensity and duration. When necessary, with the highly toxic materials, the extracts were diluted so that the lethal time exceeded four minutes. A table based on the toxicity curve of Sommer and Meyer (1937) was used to convert the lethal time to toxicity of the injected solution. The tonicity of the liaw material, expressed as mouse units per 100 grams of raw materia],, was calcolated by applying the appropriate dilution factors, A morise unit (MU) has been defined as that amount of injected shellfish poison that kills a 20 gram mouse in 15 minutes (Sommer, et al., 1948), Since Sommer and Meyer (1937) constructed their cui've from data obtained from mussels, a 3im3.1ar cur^e Tas developed from data obtained using butter clam extracts. A conrparison of the two carves demonstrated that the data reported for masael extracts cauld te used satisfactorily la the clam toxicity assay. At leasi threa mice were aaed to assay each extract. Bxtensive test8» had prowA iha.t reaultiB based on the use of three mice gav© an accuracy of better ihaTj. plas er minus iiZ percent. Errors due to variatioas in the mice, techxdqo© of iajection, and determination of death-times were reduced hy rejection of IndiTfldiiml assay results differing from the average by more than one- third. Loeatioa of KLots The locations of the teaches and the distribution of the plots were based on extensive knowledge of the clam beds in Southeastern Alaska, acquired from the general surrey. Sfine beaches which past experience had shown would yield highly toxic clamSp at least during some periods of the year, and one beach which had yielded essentially non-toxic clams, wer® selected. These beaches were distributed over as wide an area as it was practical to v3.sit fraqusntly with the laboratory's motor vessel. It is to be noted that none of the beaches chosen was from so- called outside waters, sine® preTicus investigation had shown that clams from those areas were relatively aon-toxie. However, all the beaches studied were on fairly wide channels which communicate directly with the ocean. !Ehe plots wer© on ^.laro I'eds near the mouths of bays or passages which wer© readily affectisd by the iinirrents in the large channels. None of the plots was located near the head of a bay or inlet, fhroughout the entire clam research program it was found that clams decreased in toxicity as the sampling continf^d toward the head of the bays. From one to three plots were laid out in each of the ten areas selected for study. The plois war® outlined by four iron stakes bearing metal tags stamped with the alphabetic designation of the plot. The 22 plots wer© lettered, A throtigh T, beginning with a beach near Ketchikaa and ending with a location in Frederick Sound. Locations, descriptions and characteristics of th© st-ady plots are detailed in Table 1, The ■onfavora'tel© weather during the winter months and the considerable distance of some of the beaches from Ketchikan made it impossible to ob'sain a coarplete sequence of data from each plot. This wais especially tsTi© in regard to the more northerly plots in Chatham Strait, Fort-gnately, it was possible to obtain fairly complete data from plots near Ketchikan, Plot 0 was ©mitted after October because the float at Fanshaw, which was the oa3.y safe anchorage in foul weather, was destroyed by a storm. E/Unpublished data of report in preparation. Table i. - "psNTir '.cavjon A^e: D£s::Rip~iCN of ~h£ stuov plo's Terrain SlopeI/ Area 2/ Plot locatjcn Ham 'sland S° II' 541^ N I3r 23' lO* V» Sre WtS" SIDE OF THE NOR'.'HERN TIP OF H.AM GRAVEL ■ SLAND „ (ttCNfi THE NARRCW PASSAGE CON- SAND NE.Y LEVEL I5xi4 1 WRANGELL Narrows 56° 49' 20^ N 132° 56' 4a« W On MiThOF SSLAInC, -AS" INSIDE NORTHERN ENTRANCE TO THE NARROWS^ DIRECTi-Y EAST OF Flashing Red Buov No, 42. Gravel Mud Boulders Sharp 15x5 J San Juan Island 57° 17' 35» N 1340 00' bU* W At eimtrance to Pybus Bav, 0.8 mile SOUTHWES-WARO OF PoiNT PYBUS, ADMIRALTY iSt-AND. AT MINUS TiDE THE VWO ISLANDS ARE CON^ECT£C BY A GRAVEL BAR A" THEIR WESTERN ENDS. PLO" _IES BETWEEN ROCICV OtrCROPPINGS, FORMING A POCKS'", AT SOUTHWEST END OF NORTHERN ISLAND, ON TnE EAST OR FREDERICK SOUfC SIDE OF THE GRAVEL BAR. Gravel Sand Shell B0Ua)ERS Over BEDROCK Moderate 10x5 K San Juan Island 57° i7' 35" N f34° 00' 55* W U'tMM' OiM EAST SIDE OF GRAVEL BAR, IMMEO'.ATELY SOUTH OF A WELL-DEFINED SANDY AREA, Gravel Sand Shell bouuders GENTuE 22x6 L San Juan island 57" 17' 37" N 134° 01' 10^ W On WEST OR UP-BAY SIDE OF QrAvE. BAR, NEAR WES^ END OF SOUTH IS_AND IN A POCKE" FORMED BY THE GRAVEL BtH ANO A SMAl^ SEEF. Gravel Sand Boulders Over bedrock Gentle 12X5 Pt2L. TABLE I. - ! PEWIT JFICAT! ON WD DF.Si;RiPr|ON CF "WE SrCfJCV PLOTS ( CONTINUED) LOCAT ! ON Sme TERRaTn S^0P£.I,/ AreST* RoBERvs Island 57" |8' 06" N isa** 27* 5(y W On LAWJEsr OF Roberts .slancs which form the GRAvtit. souw poitr AT Ti-e entrance to Port Houghton, Sand WHICH MAK?:S OF- "ROM STEPHENS PASSAGE, PLOT SHELL WAS ON *ES" OR Stephen? ['Assage side of a Small sp«T coN^ecTl^a eastern end of thjs island to rocks A WOOOED islet JMMEOlATELy TO THE SOUTH, GENTLE YAR03 |QX8 ROBER-rS I3LAM3 57^ tS' 00" N 133° 27 « 3G" W Tanshaw 57" l3» 00" h 133^ 30« lO" W On east or up-ba* FROM Blot m. S DG C"^ ""HE SPIT ACROSS On mainlan;; a~ sou-t-WERN em? of Cleveland Passage p vshkh lies between MAiNL.ANt) and WH ! rUSf i SL AMD „ PLOT WAS APPROX I MATELY lOOO YARDS i\!i-:^''1-W£S" 0." FANSHAW POS"' 0FT!:E. Was DISC0NTI(>iUE& AFTER OCTOBER BECdJLSE OF WSAFE -ANCHORAGE If^ FOX WHATWEP, Gravel Saw Shell Gentle 12x7 Gravel Mud Boulders Gentle 20x7 CHAJK BA';' 57'^ 13" SS'* N 134® 33' 40" W LEDGE 0,5 MSLE FROW NOP".'>< SHORE OF GRAVEL ,ASE Poiiv; ;, Admiralt!' Saw SLA^Ei, PLOT WAS OM SOt^HEASTT OR LP=BA^' SHELL SIDE OF THE LEDGEo On a baR( Chaik Bay, snsioe Vi Plot Moderate 13x5 Chaik Ba? 134'^ 33' 50" W Hoco Bav" ^■0 2g« 35^ M 134° 32» 55" W On Cha-^am S^'rait sine of ledge across from Plot P» betweei*. rockv owreRoppiNGSo Gravel Sand Boulders On east side of T^e southern end a^ Sa;^' Gravel 5SLANO5 which' is a SMAuX. I slaw QfT' the east SA(\!D shore of Hood Bav, Admiralt'v Island, and Shell ^ol"'.' i„5 mules southeasir o'f kllliswoo bouloers )3la)«„ plot was on east end of a y=3hapec ii/AShu Gentle l7xi{ GENTLE 9X7 s Hooo Bay 57=^ 26' 134^^ 33« 35" N tO" W On WES" EM) OR Cha'tham Strait s'oe of the '^'- SHAPED WASH 5 ON S^XT^€RM END Ot^ SANO 1 SLAP® 5 ACROSS ?^ROM Plot R„ SANTj Shell Gentle 13x6 T Hooo Bax' 57*^ 26' ,340 329 25» H 55" W On ENC in- SOtiTK ARM OF THE Y-SHaPED WASH., BETWEEN Plots R and S on southern po\nt of Sand l3LA^f>, Gravel Sand Shell Gentle 8x8 U SECURITY Bay On reef, awash at high tjde. ojs" west of MUD Gentle 5xiO 56" 50' 4S»' N 134*- 20' lO" W SHAL^OWBIGhT ON VCST SIDE OF C;.Err ISLAI®, SHELL liM Security Bay, ku:'.i sLA^c. Plot was on Over east end of a depression bisecting t!-c reef, bedrock Has an c-OuR of wdrogen suvpkide. Security Bav 56* 51' oOf" N 134° 2J' CS" W On the east s jde near the southern end of Harbor fsLANo, which is norhtwest of Cleft Island, in SEcuRir? Bay, GRAVEL Banc Boulders GENTLE 8x6 Sharp Slope i Moderate Slcpe; Gentle Slope % fi. drop of II FOCI IN lO FEET, A DROP OF i FOOT IN 25 FEET, A drop of I FOOT l^^ 4C' FEET. gf Area; first figure is distance parallel to water's eosEo Digcru-ssion of Egperimeatal Besults The res-alts of the monthly toxicity tests for each plot are presented in Tahle 2, The data represent the "ioiicity in mouse xmits per 100 grams of siphons or hodies. The graphic interpretation of this information is shown in Figures 1 to 9. The toxicities of "bodies ajid siphons from the same sample have been placed in the same figure. Toxicity cTorres from plots in the same locality have "been combined in one figure. The plots studied were typical of the clam beds in Southeastern Alaska in terrain and clam population. However, as was mentioned previously, nine of the plots were located on beaches of known high toxicity in order to provide clams containing determinable quantities of toxin •!;hroughout the year. This was done so that any fluct'jations in toxicity could be determined from mo::ith to month. The reactions of the mice which died when injected with the extracts of clam materials (either bodies or siphons) were identical to the reactions described for deaths due to the injection of mussel poison. Two investigators who had worked extensively with mussel poison confirmed this observation. In post-mortem examinations immediately after death, the chambers of the heart were noted to beat rhythmically; this so-called heart block is a characteristic of mussel poisoning. The seasonal toxicity characteristics of butter clams are very definitely different from those of mussels, Rytilus calif omi anus , and Washington clams, Saxidomus nuttallii. of California (Sommer and Meyer 1937) and of mussels, Rytilus edulis„ and soft shell clams, Mva arenaria„ of New Brunswick (Medcof, et al,, 19^7). Studies of the California and New Brunswick species indicate that there are short periods in the summer months when they become highly toxic. The toxicity increases rapidly and then diminishes rapidly within a few weeks. During the winter months these species are normally relatively free of ^oxln. In the present survey, except for Plot I, which had relatively non-toxic clams throughout the year, the butter clams from all the beaches showed some degree of toxicity at every saurpling. Prom a study of dino flagellates in these waters made dij.ring the sunmier of 19^9, the report of which has not yet been published,-*^ it is known that dinoflagellates of the genus (jop3^u1£lx. a member of which is the causative organism of mussel poison, do abound in the waters along the Alaskan beaches studied. The toxicity of the siphons was regularly much greater than that of the bodies. However, the ratio of toxicities of siphons to bodies is not constant. The toxicity of the siphons varies greatly from month to month, while the toxicity of the bodies does not display a similar degree of change. The ratio of the weight of siphons to bodies depends upon the care with which the siphons are removed. The data from three laboratory 2J A study of diaoflagellates in the waters of Southeastern Alaska carried out by Lucile Foster of the George Williams Hooper Foundation In cooperation with the Fieheiy Products Laboratory, experiments using 25 clams eacla show that the siphons were Ik, J to l6,4 percent of the total clam meats, Vhe eijhons were cut from the bodl©« after the manner of commercial ahucking, ia which appioximately j/h of the siphon is remoTed. In two additional experiments usiag 25 clams each, the entire siphons were pulled from the bodies. Separated in this manner, the siphons constituted 18.5 to 19.9 percent of the total clsun meats. In. a semi-commercial operation in which 290 bushels of clams were shucked raw hy a rega].ar shucking crew, who were instructed to cut off all the siphoa carefully, the siphons were 18.5 percent of the total clam meats. The £?paration of the siphons in the present- survey followed the latter method, The resu3.ts of the sur&'ey do not show uniformity in the fluctu- ation of toxicities of the clams. Brsn those from plots in the same locality do not always display the sasne vrend. There is no eTident correlation between the degree of toxicity and the terrain of the "beach, the magaife^■^.de of the tides, tenrperat'ire of the water, or amount of daylight. However, the data do suggest a recurring fluctuation in the toxicity during the year. Goaclugjoas A l6 month survey of representative clam beds in Southeastern Alaska verifies the earlier findings that a toxin or toxins, which cause reactions in mice similar to those produced by toxin frequently present in mussels (paralytic shellfish poison), is present In the butter clams of Southeastern ^aska frosa certain areas during every month, The toxicity of the siphons is usually several times greater than that of the bodies. The toxicity of the bodies does not vary greatly from month to month, while the toxicity of the siphons shows marked fluctuations. Literature Cited MEDCOr, J. C; LEIM, A. H, ; NEEULEE, AXPEEM B.; HEBULEH, A. W. H,; GIBBAED, J,; and KAUBERT, J. 1947. Paralytic shellfish poisoning on the Canadian Atlantic coast. Ball. Fish, Ees. Bd. Can., 21. PP. ^H, Ottawa, Ontario, Canada. SOMMER, H. , and MBIEER, K, F, 1937. Paralytic shellfish poisoning. Arch. Path., 24, pp. 560-598, Saja Francisco, California. SOMMER, HEEMAM; HOMIER, ROBERT P.; BIEGEL, BTBON; STAEGER, D. WAEEBIT; MOLD, JAMBS D. ; WIZHOLM, DOMLD M.; and ZIEALIS, ELIZABETH SHAME SY. 19^. Paralytic shellfish poison. I. occurrence and concentration by ion exchange, Joor, Amer, Chem, Soc, 22.* PP» 1015-1018. Table 2, - monthly toxicity survet cf bltter clam samples from plots on selected sou^heasterm a_aska btaocs PLOT rjo. LOCATION TOXICiTY, May" (946 IN MOLSE UNr,-S PER iCO GRAMS_ OF_MeAT_ July 19^ At.Gi« 1948 Sept. i948 Bodies Sjphcns Boo.es Sjdhck's Boc.es Siphons Bogies Siphons A B C D E F G H 1 J K L M N 0 P R S T U V Ham tsLAi>o Ham Island Annette Island Dall Bay Oa».l Bay' Carlton Islatc Carlton island Carlton Island Petersburg P-/BUS Bay PvBus Bay Pybus Bay Roberts Island Roberts Island Fanshaw Chaik Bay Chaik Bay Hood Bay Hood Bay Hood Bay Security Bay Security Bay 1,200 1,500 2,700 2,400 1,700 1,300 1,200 1,200 200 1,900 1,300 540 2lO 3,500 2,700 4,600 2,900 4,900 3,200 2,900 Lost 2,;ioo 2,000 !80 6,200 6,700 2.600 2,100 6,300 7,900 2,400 1,400 i„aoo 2,100 3,200 800 950 660 NEG. 1,100 1,300 620 1. 800 2,600 1,900 760 350 l„lC0 530 370 23,000 13,000 24„000 17,000 13,000 6,400 3.100 2,900 220 9,200 14,000 14,000 17,000 4,700 5,4(X) 13,000 11,000 16,000 6,700 5,000 3,800 790 1,600 2,600 1,600 •,|00 460 830 930 1,400 1,100 900 2,300 1,400 1,800 520 440 630 470 580 620 28,000 18,000 25,000 14,000 11,000 3,600 3,600 4,100 230 21,000 14,000 14,000 17,000 5,700 10,000 22,000 K,000 9,100 7,400 7,000 5,600 9,100 1,300 1,000 630 MEG, 960 1,300 1,200 660 3,200 1,900 940 360 7lO 900 350 '360 5lO 6,200 3,700 3,500 2l0 )2,0C0 10,000 t5,0C0 (3,000 15,000 12,000 17,000 7,200 11,000 4,900 5,000 7,000 13.000 A B C D C "F 6 H I J K L M N 0 P Q R S T U V Table 2„ - monthly toxi ICITY SURVEY OF BUTTER CLAM SAMPLES i FROM PLOTS ON SELECTED Southeastern Alaska beaches - Continued Location BODIES Toxic iTv„ 1948 .IN MOUSE UNITS PER lOO GS, ftMS OF MEAT Plot NOV. 1948 DE. Bodies :. 1948 Siphons Jan, Bodies 1949 . No. S:phons Bodies Siphons S 1 PHONS Ham island Ham Island AN^€TTE Island Dall Bay Dall Bay Carlton Island Carlton Island Carlton Islaio Petersburg Pybus Bay Pybus Bay f*«Bws Bay Roberts Island ftoBERTS Island Fanshaw Chaik Bay Chaik Bay Hooo Bay Hood Bay Hood Bay Security Bay Security Bay 2,500 1,600 2,000 1,100 1,000 780 Neg. I„l00 2,000 1,300 1,700 3,900 1,600 760 400 1,100 590 860 I.JOO 1,000 5,100 5^700 4,900 6,500 4,300 Lost 220 (9,000 13,000 (7,000 18,000 16,000 13,000 14,000 5,900 9,500 7,900 8,300 13,000 13,000 l»700 3,600 670 970 8=0 NEG, 760 840 930 1,500 1,-00 Omitted 1,400 920 780 2,600 3,400 1,000 1,200 970 12,000 5,800 6,900 (9,000 (2,000 6,600 1,600 550 1,000 2,300 3,(00 4,(00 4,800 5,400 16,000 !,600 1,100 2,lC0 2lO = '- NEG, ((,000 ... (0,000 11,000 (8,000 ... 8,700 ... FROM FURTHER SAMPLING AFTER OCTOBER (9,000 11,000 (8,000 14,000 (2,000 2lO 8lO 400 3,000 6,200 sel ected South; -.'STERN Alaska beaches - CONTINLIED Locat ion Toxicirf„ IN MOUSE UN its per IOO grams Or meat Plot Feb. L949 MaRo 1949 Apr, I 1949 May 1949 No, Bodies Siphons Bodies Siphons Bod.es S 1 PHONS Bodies Siphons A Ham islwc 1,500 24,000 2,000 21,000 2,200 22,000 3,000 20,000 B H.4tt Island 1,000 12,000 1,100 7,900 670 11,000 2,100 ;J,CtX) C Annedt Island !,|00 17,000 2,200 |9„000 1,300 |4,CC0 2,400 16,000 0 Oali. Bay „ 2,600 lO,(J00 3,500 13,000 E DAf.L Bay „ B _ . 2,400 11,000 3,800 10,000 F Carlton IsU(\)D „ _ eTo 5,500 700 4,800 870 3,000 G CARLTCV la^VND _ _ l.lOO 4,400 1,400 4,700 630 4,200 H Carlton island - » 650 3,200 ■ Hon 3,900 690 3,700 1 PtTERSBLRS _ . NEGo 200 NEG. 200 NEG« NEG. J PVBbS Bav o • 1,100 13,000 1,500 16,000 1,800 |6,U00 K PyoUS Bay . _ 1,300 8,300 (,600 to,uuu 1,700 9,600 L PvBus Bay • » 1,300 12,000 920 11,000 l,4C0 14,000 M Roberts island - . 1,600 15,000 1,200 14,000 1,400 11,000 N RoBCR^s Island - - 2,600 16,000 3,200 13,000 2,300 9,200 0 Faims-ww Omitted from further sampling after 0; :tober P Chaik Bay _ _ 640 10,000 700 11,000 590 8,30C' Q Chaix Bay . Cl 970 8,100 750 6,40C< 600 6,800 R Hood Bav • o 1,100 11,000 540 3,300 680 9,500 S Hood Bay _ c 480 4,20) 760 5,800 660 4,200 T Hood Bay . . 560 4,60C! 750 6,300 840 3,900 L! SE'X'air.' Bav c. a 470 6,500 40* 5,600 240 3,900 V SEouRtTv Bay - - 690 9,300 540 7,900 790 7,600 Tabu 2. - Monthly toxicity survey of bltter - CLAM SAMPLES ; from plots on - Continued selected Southeastern Alaska beacs^es LOCAT ! ON Toxicity. IN MOUSE UN l!TS PER lOO grams 0- MEAT Plot June 1949 July 1949 AUG, 1949 Sept . 1949 No. Bodies Siphons Bodies . Siphons Bodies Siphons 12,000 Bodies 1,800 SIPHONS A Ham JsLAhc . . 1,400 |6,0CX) 2,100 13,000 B Ham i3LA^e „ o 620 5,600 1,500 7,900 1,500 ll.CXX) C Ammet""e Island « _ 1,500 \l,CCO 2,700 12,000 1,900 (2,000 D Dall Bay „ _ o. . 1,800 6,8CX) 1,900 9,700 E Dail Bav « « 2,800 4,100 3,100 4,100 3,300 8,800 F Carlton I slaw 2,100 5,500 1,600 7,5CX) l,4C0 11,000 = - G Carlton Island 1,300 5,400 1,800 LOST 1,400 7,600 - - H Carltcn Island 1,000 3,400 Lost 8,300 l,40C. 13,000 - = 1 PETtftSBURG NEGo NEG. NEG. NEG. = = - " J P-VBL'S BA? 1,400 |2,UU0 1,900 9, £00 l,l-X 7,300 = = K Pybus Say 1,700 8,800 1,600 S,-500 IJOO 11,000 - - L Pybus Bw 1,300 15,000 1,200 16,000 1,200 13,000 = - U Roberts Island 1,900 10,000 2, AX) 14,000 1,100 I2,000 - - N Roberts Island 2,000 13,000 2,500 14,000 1,400 9,700 - - 0 F«*rvSnAw Omitted from further sampling ArTER i October P Chaik Bay 850 11,000 1,500 16,000 560 11,000 -> - Q Chaik Bay 760 7,700 1,200 9,603 750 10,000 - - R Hood Bay 1,100 9,300 1,400 8,000 480 lljUUO - - S Hoo) Bay 800 6,500 1,100 9,600 580 6,500 o - T Hood Bay //U 4,800 1,000 8,100 280 5,000 - m U SfeTij«i'.-Y Bay 760 5,200 1,200 10,000 350 6,600 - - V Security bay BlO 9,100 1,100 7,800 540 7,800 • * Figures 1 to 9 show graphically the monthly variation in toxicity of the bodies and siphons of buttex' clam samples from plots on selected Southeastern Alaska beaches « 10 Interior-=-Duplioating Section, Washington, Do C<. 8276.3 4J O rH ft cd o i m «0 N CD C«l CM — iovui tiaft 001 J*tf o u a < €L < « > w O — ra Pi -I 1 1 »- o ■4 « N -I »- H h -I 1 ' lo»ui lUiO 001 •>•' n H ipuotnoMl N « X + + -t- ir •+- -a F-=4 to o a m M C o H a o to O n M est — -• — loaui tuiS 001 J*d n N tpuotnoqi totui tuil 001 '•^ n N tpuoflnoiix o •o ■i h CM (oauj »% I 0 d*! *»^ n H tpuotnoMl O - (b M 10 M CSJ t D • Ul • ui 6 0 0 1 -B