17 



As with the chlorinated catechols, there was only a small 

 difference between the concentration of chlorinated phenol which 

 caused 100 per cent mortality and that which caused none during 

 96-hr exposure of sockeyc fry from Pitt Lake incubation channel. 

 Tetrachlorophenol caused 100 per cent mortality at 0.5C ppm and 

 none at 0.45 ppm while comparable figures for dichlorophenol were 

 1.8 and 1.5 ppm. 



Condition and Behavior of Test Fish 



All fish tested appeared outwardly to be in good condition. 

 Behavior of experimental and control fish was observed during all 

 bioassays and the only outward symptom of toxicity noted was loss 

 of equilibrium several hours before death. In general, those fish 

 which survived bioassays behaved as the control fish did. Pink 

 salmon fry were especially excitable, possibly due to their urge 

 to migrate, and the level of activity in both control and experimental 

 aquaria was high. However, it was concluded that observable activity 

 of pink and sockeye was independent of tetra- or dichlorocatechol 

 concentration at sublethal levels. 



Effect of Chlorinated Catechols on iiespiration 



Sockeye Salmon Alevins 



Measurements indicated that sublethal concentrations of 

 tetrachlorocatechol caused increased oxygen utilization (respiration 

 rate) by sockeye salmon alevins. The relative respiration rate of 

 hatchery-incubated Cultus Lake sockeye alevins in 0.75 ppm 

 tetrachlorocatechol was 1.6l, indicating a 61 per cent increase in 

 respiration over the control rate (TABLE 5, Trial A) . The relative 

 rate decreased as concentration of tetrachlorocatechol was reduced 

 so that at 0.125 ppm the respiration rate was only seven per cent 

 greater than that of the controls. The results represent samples of 

 20 alevins at each .concentration and in each of the two controls. 



