catechols. However, an indication of the likelihood of successfiil 

 biological oxidation of chlorinated catechols may be obtained by 

 reference to oxidation of the structurally similar chlorinated 

 phenols. Research has shown that biological treatment oxidized 

 mono-, di- and trichlorophenol while pentachlorophenol was 

 resistant (Ingols, Gaffney and Stevenson, 1966), Based upon these 

 data, and the fact that catechol itself can be oxidized, it is 

 likely that dichlorocatechol would be oxidized during biological 

 treatment. The fate of tetrachlorocatechol cannot be so easily 

 estimated and was determined experimentally in the present study. 



MATii-KlALS MD i'ETHODS 



Sources of Fish 



Pink and sockeye salmon used in the present experiments were 

 obtained from various sources. All sockeye were of the Cultus Lake 

 or Pitt Kiver races. Some Cultus Lake sockeye alevins were 

 incubated in the Cultus Lake hatchery while others originated from 

 naturally spaxmed stock. The latter alevins were dug from redds 

 on the Lindell Beach spawning ground of Cultus Lake. Sockeye smolts 

 were trapped in Sweltzer Creek during their seaward migration from 

 Cultus Lake. Pitt River sockeye fry were reared in outdoor ponds 

 at Cultus Lake hatchery following transfer from an incubation 

 channel at Pitt Pdver. 



The pink salmon alevins used in the present tests originated 

 from Skeena riiver (courtesy Department of Fisheries of Canada) and 

 from Sweltzer Creek. Both stocks were hatchery incubated. Pink 

 salmon fry were obtained during migration from an incubation channel 

 used by Sweltzer Creek stocks. 



The origin of fish used in each test is restated where applicable 

 in the .^SULTS. 



