Constant concentrations of di- and tetrachlorocatechol v/erc 

 maintained by metering fresh Cultus Lake water ajid a 25-ppm solution 

 of the respective toxicant into the troughs using overflow plastic 

 headboxes. Water and solutions were well mixed by introduction of 

 compressed air through air stones at the inlet end of the troughs, 

 Dissolveu oxygen v;as near saturation (12 ppm) , 



iilevins in Groups 1 and 2 were hatchery-incubated Cultus Lake 



race sockeye. The fish in Groups 1 and 2 were taken from hatchery 



baskets and acclimated to the apparatus for eight and six days, 



respectively, before the test solutions were introduced. No 



mortalities occurred auring the acclimation period. Group 1 alevins 



were further advanced than those in Group 2 and at the time that the 



test solutions were introduced to the troughs they had accumulated 



1,500 and 1,300 temperature iinits, respectively. Fish in Group 1 



reached the '' swim-up" fry stage about 14 days after addition of the 



test solution while those in Group 2 required 29 days. Exposiire to 



toxicant was continuous for 31 days for each group: Group 1 for lA 



days as alevins and 17 days as fry, an.j. Group 2 for 29 days as 



1 

 alevins and two days as fry. ^"ry were fed Abernathy dry aiet, 



in excess, eight times per day commencing at ''swim-up". 



MeasLirements of Respiration Rate 



The effect of chlorinated catechols on respiration rate was 

 determined by comparing oxygen consumption of experimental and 

 control groups of young sockeye and pink salmon during a 5-hr period, 

 Prior to testing, fish were helu overnight in one liter plastic 

 aquaria in the saine concentration of di- or tetrachlorocatechol at 

 which they were to be tested the next day, except in a few cases 

 described m the RESULTS. Fish were held and tested at the 

 temperatirre of the water from which they were taken. Fry were not 

 fed for A8 hr before testing. 



1 Developed at the U.S. Fish and VJildlife Service Salmon 

 Cultural Laboratory, Abernathy Creek, Longview, Washington. 



