FISHERY BULLETIN: VOL. 78, NO. 3 



100 



16 22 28 

 FEB 



1 1 r- 



12 18 24 30 

 MAR 



-i 1 r- 



12 18 24 

 APR 



30 



Figure 3 . — Daily cumulative percent of emergence of pink salmon fry that did not receive exposure to ammonia (controls) or received a 

 single 24-h exposure to ammonia sometime prior to normal emergence. The dates when the 24-h exposures began are indicated by 

 arrows and exposure concentrations. Three ranges of un-ionized ammonia concentrations were used: 1) <25 ppb (not shown) which 

 resulted in <1% immediate emergence. The date of 50% emergence was within ±3 d of 50% control emergence, 2) 30-60 ppb of 

 un-ionized ammonia (upper), 3) 90-150 ppb of un-ionized ammonia (lower). Asterisk indicates the lack of initial emergence (<1%) in 

 response to ammonia exposures ( same pattern as controls). 



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