2 percent, had injuries (table 21). This is com- 

 pared to an injury incidence of about 0.5 

 percent in 1962. Since the counters could see 

 only the top and one side of each fish, the 

 incidence of injury might have been greater 

 than observed. Of the total number of injured 

 fish observed in 1963, about 64, 19, and 17 

 percent were recorded in the left, middle and 

 right ladders, respectively. These percentages 

 agree roughly with the percentages of the runs 

 using each of the ladders. 



As in 1962, the greatest number of injuries 

 were observed on the large chinook and sock- 

 eye salmon. In the 2-week period July 16-31, 

 29,908 sockeye were counted through the fish- 

 ways and injuries were noted on approximately 

 4 percent of the fish. In the same period in 

 1962, the incidence of injuries on sockeye 

 salmon amounted to approximately 0.2 per- 

 cent. 



Circular cuts or abrasions were the most 

 numerous injuries observed at Rock Island 

 Dam in 1963. Pathologic examination of these 

 injuries by personnel of College of Fisheries, 

 University of Washington, indicated a very 

 high incidence of Bacillus columnaris disease 

 in the cut and abraded areas. 



In 1963, 156 chinook salmon bearing num- 

 bered Peterson disk tags were counted through 

 the fishways at Rock Island Dam. These fish 

 had been trapped and tagged by Washington 

 Department of Fisheries personnel at Priest 

 Rapids Dam, located approximately 52 miles 

 downstream from Rock Island Dam. Purpose 

 of the tagging experiment was to determine 

 proper time for trapping fall chinook salmon 

 for stocking the Priest Rapids -Wanapum 

 spawning channel. 



One chinook salmon with a small red disk 

 tag attached just below the dorsal fin, of a 

 kind not employed at Priest Rapids, was ob- 

 served at Rock Island. 



On July 10, 11, 12, 17, 18, 19, and 24, 731 

 sockeye were trapped and identified with num- 

 bered Peterson disk tags at the left ladder at 

 Rock Island Dam. These fish were released 

 into the Rock Island pool approximately one- 

 quarter mile above the dam. An additional 

 117 sockeye were trapped at the left ladder, 

 marked with a pressure sprayed fluorescent 

 paint, and released at the same location as 

 the tagged fish. The painted mark was on the 

 left side and about 1 inch in diameter. This 

 tagging and marking program was conducted 

 by Bureau of Commercial Fisheries as part 

 of an evaluation study of fish passage facili- 

 ties at Rocky Reach Dam, located approxi- 

 mately 26 miles upstream from Rock Island 

 Dam. 



The middle fish ladder at Rock Island Dam 

 was inoperative from May 1-20, due to low 

 tailwater conditions. During this period modi- 

 fications were made to the fishway entrance and 

 rise in tailwater on May 21 permitted resump- 

 tion of ladder operation. Prior to counting on 



May 1, modifications also were made to the 

 left fish ladder. 



To secure information regarding night move- 

 ment of fish at Rock Island Dam, limited 

 counting was conducted at the left fish ladder 

 on July 19, between 9 p.m. and 11:30 p.m. 

 Artificial light was used to permit identifi- 

 cation of fish moving over the counting board. 

 Twenty- six sockeye, one chinook, ten suckers, 

 twelve squawfish, and seven whitefish migrated 

 up the ladder in that night period. 



On August 8, modifications were made to 

 the water supply conduit at the middle ladder 

 to increase the flow of auxiliary water. An 

 increase in fish movement through the ladder 

 was noted. 



On August 27, the west side entrance of the 

 middle ladder was opened and additional aux- 

 iliary water provided. 



The right ladder was closed on September 

 1, and reopened on the same day. Closure 

 was made in order to permit removal of de- 

 bris. 



Frequent inspections were made of fishway 

 operations by State and Federal personnel 

 throughout the counting season. 



SUMMARY 



1. The total Rock Island count of salmon 

 and steelhead in 1963 was 106,554, about 34,800 

 more than in 1962. 



2. The chinook salmon count of 34,688 (jacks 

 included) in 1963 greatly exceeded the mean 

 of 16,777 for the 30-year period 1933-62 and 

 was about 500 more than in 1962 and more 

 than one-half the peak year of 1957. In 1963, 

 19,409 jacks were recorded, representing 

 about 56 percent of that year's total of chinook 

 salmon counted. In 1962, jacks represented 

 about 21 percent of the chinook run. 



3. The sockeye count of 64,768 in 1963 was 

 about 13,600 more than the 30-year mean of 

 51,164 and exceeded the 1962 count by about 

 35,500 fish. 



4. The coho salmon count of 20 fish in 1963 

 was about 25 percent of the 30-year mean of 

 83 fish and less than 3 percent of the 1962 

 count of 737 fish. 



5. The steelhead count of 7,078 in 1963 

 was slightly more than twice the 30-year 

 mean of 3,336 and was about 500 less than 

 recorded in 1962. 



6. In 1963, as in previous years, more 

 salmon and steelhead used the left bank fish 

 ladder than either of the other ladders. 



7. Fish counting in 1963 began May 1 and 

 terminated October 30. From May 1 through 

 August 31, counting was conducted for 16 

 hours each day; from September 1 through 

 October 30, 14 hours each day (6 a.m. to 

 8 p.m.) to conform with the daylight avail- 

 able. 



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