these hoods, migrant mortality has 

 been nearly eliminated.* Observations 

 made prior to installation of the pro- 

 tective hoods indicated some of the 

 migrants emerging from the draft tubes 

 into the tailwater were stunned and 

 became easy prey for predators and 

 gulls. 



In 1959, trapping of fish from the 

 left bank fish ladder was conducted 

 for the following experiments: 



1. Collection oi Chondro coccus col- 

 umnaris cultures by Washington 

 School of Fisheries --July 17, 

 from 10:20 a.m. to 1:45 p.m.; 

 July 24, from 7:10 a.m. to 

 9:45 a.m.; and August 7, from 

 8:00 a.m. to 10:45 a.m. 



2. Middle fish ladder, from 

 8:00 a.m. to 4:00 p.m. No- 

 vember 23, 1959, for inspection 

 and cleaning. 



3. Right bank fish ladder, from 

 8:00 a.m. to 4:00 p.m. Novem- 

 ber 25, 1959, for inspection and 

 cleaning. 



4. Left ladder, from 8:00 a.nn. to 

 4:00 p.m. November 24, 1959, 

 for inspection and cleaning. 



Some slight variation in the spillway 

 gate opening sequence was necessary 

 during the season due to damaged guide 

 rails in the gate slots. This variation 

 was not of sufficient consequence to 

 cause adverse effects on the fish runs. 



2. Effect of light on maturation stud- 

 ies by Bureau of Sport Fisheries 

 and Wildlife, National Fish Hatch- 

 ery, Entiat, Wash. --July 23, fronn 

 6:30 a.m. to 2:20 p.m. 



3. Fecundity studies by Bureau of 

 Commercial Fisheries Biological 

 Laboratory, Seattle, Wash.-- 

 July 23, in conjunction with trap- 

 ping blueback for Entiat Hatch- 

 ery. 



The four times that it was necessary 

 to dewater the fish ladder during 1959 

 are as follows: 



Middle fish ladder, from 

 10:00 a.m. January 12, 1959, to 

 1:30 p.m. January 13, 1959, to 

 repair broken links on telescopic 

 gate chains. 



* Biological Report, Rocky tteach Fisheries Research 

 Program, 1958, Washington Department of Fisheries 

 (Unpublished). 



Rock Island Project. Alleviation of Mortality to Down- 

 stream Migrant Salmonids on Cooling Water Screens, 

 February 23, 1960, Chelan County Public UtiUty District. 

 (Unpublished). 



During the year the Bureau of Com- 

 mercial Fisheries installed experi- 

 mental electronic fish counting tunnels 

 in left bank fishway at Rock Island 

 Dam. The studies were conducted in 

 such fashion as to not interfere with 

 regular counting operations. 



SUMMARY 



1. The total Rock Island Dam count 

 of salmon and steelhead in 1959 

 was 99,959 which was less than the 

 1958 count of 135,182. 



2. Yearly total counts of fish passing 

 Rock Island Dam during the period 

 1933-1959, inclusive, are given in 

 table 1. 



3. The Chinook salmon count of 

 23,352 in 1959 was less than in 

 1958 and less than half the peak 

 year of 1957. In 1959, 5,960 jacks 

 were recorded, representing 25.5 

 percent of that year's count. 



4. The sockeye count of 72,35 1 in 1959 

 was less than in 1958 but exceeded 

 the 26-year mean of 52,073. A 



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