31 



Furthermore, there appeared to be no difference in resistance 

 to tetrachlorocatechol between Ciiltus Lake and Pitt Lake sockeye. 

 On the other hand, advancea sockeye alevins were more resistant 

 and had an average 96-l:ir TL of 1.2 ppm. 



Jiff crunces intolerance to tetrachlorocatechol of sockeye at 

 various life stages may have been related to density of fish in the 

 bioassay solutions, to the stage of development, or both. In some 

 instances reported in the literature, apparent differences in 

 tolerance have been caused by unequal densities of fish in the 

 bioassay solutions in terras of grams of fish per liter. Katz and 

 Chadwick (1961) found that at low densities of fish, mortalities 

 occurred at low concentrations of toxicant (ii,ndrin), while high 

 concentrations of toxicant were required to cause mortality at 

 greater fish densities. On the other hand. Goodnight (1942) found 

 that density of fish and temperatures v;ithin the normal range had 

 no effect on toxicity of pentachlorophenol to several species of 

 fish. Goodnight (1942) also reported that newly hatched lake trout 

 alevins, Salvolinus namaycush , were more sensitive to 

 pentachlorophenol than were juvenile fish. In the results reported 

 herein, fish density did not appear to be the cause of the greater 

 resistance of advanced alevins since they were tested at lower 

 density (0.6 gm/liter) than were fry (2.0, 0.8 gm/liter) and smolts 

 (3.9 gm/liter) as seen in IkuLuIj 1. j?reshly hatched alevins were 

 bioassayed at a density of 0.3 gTa/litcr compared to 0.6 gm/liter 

 for advanced alevins, but Goodnight 's (194.2) results with 

 pentachlorophenol indicate that this difference in density would not 

 have affected resistance of the newly hatched and advanced alevins. 

 It appears likely, based upon the foregoing arguments, that freshly 

 hatched sockeye alevins, fry and smolts were less tolerant of 

 tetrachlorocatechol than were advanced sockeye alevins. 



Pinlc salmon alevins raid fry had 96-hr TL 's of 0.29 and 0.26 

 ppm, respectively, and were less tolerant of tetrachlorocatechol 

 than were sockeye. as an average it would appear that young pink 



