other fishes floating dovmstream below the dam at f^arious times of the 

 year. The Corps of 'Fngineers accordingly instructed its biologists to 

 make periodic trips dovmstream in a boat to learn the extent of mortality, 

 and if possible, to determine if the fishes died as a result of injuries 

 received at Bonneville Damo These studies have been carried on for the 

 past eight years (Appendix, Table 3) o Data obtained during the fall 

 migration period in September 1946 by the U. S. Fish and Yfildlife Service 

 in cooperation with the Corps of Engineers are included in the text. 



SECTION I 



INJURED FISH STimiES 



Injur ies Observed at Bonne-vllle Dam« For several years, it has been 

 the practice for the fish counters at Bonneville Dam to keep a record of 

 the number of injured fish observed. Prior to 1941 they had recorded 

 merely that there was an apparent injury on the fish, and then only those 

 injuries deemed "Serious'* were recorded. In May 1943, during the height 

 of the spring rim of saMon,, a more detailed record was kept, showing not 

 only the number of injuries but also the type and location of each injuryo 



Injuries, 1943. In a sample of 37.805 chinook salmon passing up the 

 ladders during May of 1943, 339 shov/ed injuries. Of this nuniber, 165 or 

 about 49 percent were injuries to the dorsal fin, and the remaining 174 

 were injuries to other parts of the body of the fish. 



l^et I njuries, Chinook Salmon, 1946 . In the STimner of 1946^ a series 

 of SBmple counts wps made at counting stations in the fish ladders at 

 Bonneville Dam to determine the frequency of net marks and other injuries. 

 Injuries other than those obviously caused by nets were wounds and abrasions 

 on various parts of the body of the fish. In some cases, there were deep 

 gouges on the flesh along sides and peduncle area. In others, large torn 

 patches of skin were hanging loose,, leaving the muscle tissue exposed j 

 and in still others, fungus patches had begun to form ou previous cuts 

 or abrasions on the snout and tail. The numbers of net and other injuries 

 during June, July, and Aurust 1946 are shown in Table 1. 



Injuries Observed Above and Below Bonneville Dam . In order to 

 determine whether there were more injured fish above Bonneville Dam than 

 belOTf and the types of injuries present at each locality, observers were 

 stationed at Big White Salmon and at Bonneville Hatchei^ie; during the 

 height of spawning activities. Pig White Salmon Ititchery is on the 

 Washington Shore approximately 30 miles above the dam, and Bonneville 

 Hatchery is approximately one mile below the dam on the Oregon shore. 



At each hatchery the observers daily recorded the following data 

 for Chinook salmon: (a) total n-jmber of fish examined, (b) dorsal and 

 ventral fin cuts or abrasions, (c) completely encircling abrasions, and 

 (d) other injuries. 



