24 



Pink Salmon Alevins 



Sublethal concentrations of tetrachlorocatechol caused the 

 rate of oxygen utilization by pink salmon alevins to increase. 

 The relative respiration rate of Sweltzer Creek pink salmon 

 alevins reached a maximum of about 1.5 butween G.175 and 0,250 ppm 

 tetrachlorocatechol (TABLE 7). At 0,150 ppm tetrachlorocatechol, 

 relative respiration rate dropped sharply to I.l6 and continued 

 to drop to less t'lan unity at 0.125 and 0.100 ppm. At 0,050 ppm 

 tetrachlorocatecholj relative respiration rate rose to unity. 

 Relative respiration rates less than unity were possibly due to 

 experip.ental variation, in which case it appears that respiration 

 rate vas not affected at tetrachlorocatechol concentrations of, 

 or below, 0.125 ppm. 



Relative respiration rates of Skeena River stock alevins were 

 determined to be 1.33 and 1.35 in two trials at 0.25 ppm 

 tetrachlorocatechol (TABLE 7). These rates are less than the 

 value of 1,48 determinea for Sv/eltzer Greek alevins and may have 

 been due to the fact that Skeena alevins were larger than those 

 from Sv^ltzer Creek. Trials K and i^I were conducted on successive 

 dr.j'-s using different individual fish from the same hatchery basket. 

 A sample of 20 fish from the basket was used to obtain the weights 

 report din TABLL 7 for these two trials. 



The mean relative respiration rates of alevins. were plotted in 

 FIGURE 3 where the trends in data already discussed can be seen 

 graphically.- It can be concluded that respiration rate was increased 

 at concentrations greater than C.125 ppm tetrachlorocatechol, but 

 that further research would be required to confirm the possible 

 decrease in respiration rate noted at lower concentrations of 

 tetrachlorocatechol . 



