248 



ERNEST 0. SALO 



In 1966 in Elliott Bay we released 441,646 

 marked fish. We sampled 21 days with an actual 75 hours 

 of net time, and we recovered 31,000 salmon, of which 

 2,894 were marked. Now, these were marked with a 

 fluorescent pigment that is visible only under ultraviolet 

 light. The technique was invented somewhere else, but we 

 developed it at FRI. 



Even with this amount of effort we found 

 our mortality estimates biased and possibly misleading, 

 so the experiment was repeated in the spring of 1967. 

 The field work has just been concluded. 



This year we marked and released 531,398 

 fish, a half a million, we tow netted for 32 days with a 

 total of 140 hours of sampling time, and we recovered 

 5,200 marked fish. 



Our mortality estimates, I believe, this 

 year are valid. This year we modified the experiment a 

 little bit by releasing at different water times under 

 different flow conditions. We received the cooperation 

 of people at Howard Hanson Dam. 



The locations of the capture of these fish 

 are recorded, as are the associated water quality para- 

 meters. Sampling occurred from May through the first part 

 of July, when the fish no longer are available to the 



