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 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. 



