155 



1 J. E. LASATER 



2 profound effects on survival or destruction of the popu- 



3 lation of concern. 



4 The use of oyster larvae bioassays have 



5 been challenged on the grounds that this assay considers 

 5 only a single delicate stage of the animal's life cycle 



7 and as such cannot be used in making inferences about 



g effect on adults or the population. It should be obvious 



9 to even the most poorly informed that if reproduction of 



10 the animal is stopped, there will very shortly be no 



11 survivors to concern ourselves with. In addition to this, 



12 we must note that research by the Department of Fisheries 



13 indicates toxicities of some wastes as measured by per- 



14 cent abnormal larvae in the 48~hour Pacific oyster embryo 



15 bioassay closely parallel toxicity levels determined 

 Ig through increased mortalities, decreased fatness, and 



17 reduced reproduction by adult oysters. 



18 However, the roost damning finding of the 



19 bioassay studies reported by the Conference is the 



20 results of bioassays conducted before, during, and sub- 



21 sequent to the complete shutdown of a single industry in 



22 the autumn of 1964 in three of the four areas being con- 



23 sidered by this conference. During this period frequent 



24 1 oyster larvae bioassays clearly showed the decline to 

 virtually no toxicity of the waters in the absence of 



25 



