FISHERY BULLETIN: VOL. 74, NO. 1 



DAY OF EMERGENCE 



Figure 3. — Timing of coho salmon fry emergence from the 

 simulated redds. 



The average size of fry increased significantly 

 (P<0.01) as emergence proceeded but the largest 

 fry emerged during the peak of emergence from 

 day 10 to day 15 (Figure 4). 



More fry emerged at night than during the day 

 in redds 2 and 3 (57% and 60%, respectively), but 

 more fry emerged during the day in redd 1 (Table 

 1). No preference was shown by fry in redd 4 

 which emerged in equal numbers. Dividing the 

 data into two time intervals, days 1 through 11, 

 and days 12 through 24, revealed that emergence 

 during the day increased some 30% in all four 

 redds in the latter period. 



Emerging fry showed a strong positive current 

 response, the majority (69-82%) moving upstream 

 subsequent to emergence, upstream movement 

 increasing but slightly as emergence proceeded. 



There were no significant differences in aver- 

 age length and weight (P<0.01) of fry moving up- 

 stream or downstream following emergence, but 

 fry emerging during the day were, on the aver- 

 age, larger than those emerging at night (Table 

 1), significantly so in two redds (redd 3, P<0.05; 





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DAY OF EMERGENCE 

 Figure 4. — Size of coho salmon fry at emergence including the regression lines. 



170 



