FISHERY BULLETIN; VOL. 72, NO. 4 



50 



2A. 36.I*C EXPOSURE 



t TREATMENT 



90 



2B. 21* C EXPOSURE 



1200 0000 1200 0000 1200 0000 1200 0000 1200 0000 1200 0000 1200 



TIME(H) 



Figure 2. — Median hourly tunnel passes by fish throughout the entire 6-day experiment for each treat- 

 ment group. The arrow indicates time of treatment. 



to compare the 3-day pretreatment and 3-day 

 posttreatment median hourly activities. The pre- 

 treatment and posttreatment activity levels of 

 the control group were not significantly different. 

 The daytime posttreatment activity of cold- 

 treated fish, although higher and more variable, 

 was not significantly changed; however, night 

 activity increased (P<0.001). Heat-treated fish 

 demonstrated the greatest change in activity. 



Both night and daytime activities decreased 

 (P<0.01,P<0.001 respectively). 



DISCUSSION 



Combined pretreatment data demonstrate that 

 the 32 test bluegills maintained their environ- 

 mental temperatures within well-defined limits 

 relative to the available temperature range. The 



1090 



