Subject: Tests to Determine the Time Factor in the Floating of Dead 

 Salmonbid Fishes, Bonneville Dam, 1945 (Continued) 



It should be pointed out that the observed times reauired for the 

 specimens to float and to remain afloat is probably greater than the 

 actual time in both cases. The specimens could have floated up or sank 

 ajiy time between the time they were first seen or disappeared and the 

 previous observation. A difference of as great as 24 hours is possiblco 



Observations upon the physical condition of the specimens as they 

 floated to the surface would seem to indicate that it would be difficult 

 for scavengers to destroy the fish sufficiently to prevent its raising to 

 the s\arface, provided it was not held under water by some physical obstruc- 

 tion. It is possible that fish v/ith cuts or skin abrasions would be more 

 easily attacked and eatent The fish used in these tests developed a heavy 

 growth of fungus, a condition not noticed in the natural river mortality 

 to any extent. Perhaps the abundant fungus growth was due to the fish 

 being held in more or less quiet water away from "tiie influence of v/lnd and 

 current. It should be realized that the behavior of the fish under observa- 

 tion would not necessarily be that of fish floating free in the water. 



Charles B. Wade 

 Aquatic Biologist 



41 



Interior Duplicating Section, Washington 25, T.C. 83913 



