COUNTING PROCEDURES 



Fish counting in 1962 began on May 1 and 

 terminated on October 27. From May 1 through 

 September 13, fish were counted 16 hours each 

 day, starting at 5 a.m. and ending at 9 p.m. 

 From September 14 through October 27, count- 

 ing was reduced to conform to the hours of 

 daylight available. 



Fish counters were allowed a 15- minute 

 rest period at the end of each hour; and during 

 all periods of noncounting, ladders were closed 

 to passage of fish. 



the season, jacks rarely, if ever, exceed 22 

 inches in length. Consequently, jacks at Rock 

 Island Dam are identified as all chinook salmon 

 18 inches or less in length prior to July 1 

 and 22 inches or less in length after that date. 

 The maximum daily count of 173 jacks oc- 

 curred on August 7 (table 3). The 7,118 fish 

 recorded as jacks constitute 20.8 percent of 

 the 1962 chinook salmon run as compared to 

 28.0 percent in 1961. 



Table 5 shows the number and percentage 

 of chinook salmon jacks counted over each fish 

 ladder. Monthly totals are given in table 2. 



ENUMERATION OF FISH 



Chinook Salmon, Oncorhynchus 

 tshawytscha 



The 1962 chinook salmon count of 34,154 

 (jacks included) was well above the mean of 

 16,178 for the 29- year period 1933-61. It was 

 also greater than the 1961 count, but only 

 67 percent of the record count of 50,713 in 

 1957 (table 1). Monthly totals of chinook 

 salmon counted are given in table 2. Maximum 

 day's count of chinook salmon, jacks not in- 

 cluded, inl962 was 570 on August 10 (table 3). 

 Tables 4 and 5 show semimonthly totals of 

 the number and percentage of chinook salmon 

 counted over each fish ladder. Of the chinook 

 salmon (jacks excluded) which passed Rock 

 Island Dam in 1962, 65.6 percent ascended the 

 left ladder, while 13.5 and 20.9 percent as- 

 cended the middle and right ladders, re- 

 spectively. The count of 8 chinook salmon on 

 May 1, 1962, is in sharp contrast to the 137 

 on the same date in 1961. 



Chinook Salmon Jacks 



Some chinook salmon return from the ocean 

 as mature fish in the year following their 

 seaward migration and are referred to as 

 "jacks." These fish are small and predomi- 

 nantly males. It has been determined at Rock 

 Island Dam that up to June 30 of each year, 

 jacks rarely, if ever, exceed 18 inches in 

 length, while other chinook salmon are much 

 larger. Likewise, from July 1 to the end of 



Sockeye Salmon, Oncorhynchus nerka 

 (Blueback or Red) 



The 1962 sockeye salmon count of 29,253 

 was 56 percent of the 29-year mean of 51,920 

 (table 1). In 1962, peak of the run was reached 

 on July 21, when 2,541 fish were counted 

 through the fishways at Rock Island Dam. 



Table 6 shows semimonthly totals of the 

 number and percentage of sockeye salmon 

 counted over each ladder. Of the sockeye 

 salmon passing Rock Island Dam in 1962, 

 48.3 percent ascended the left ladder, while 

 21.7 and 30.0 percent ascended the middle and 

 right ladders, respectively. Data pertaining to 

 sockeye salmon daily counts are in tables 9-14. 

 Monthly totals of sockeye salmon counted in 

 1962 are in table 2. 



Coho Salmon, Oncorhynchus kisutch 

 (Silver) 



The 1962 coho salmon count of 737 fish 

 greatly exceeded the 29-year mean of 60 and 

 the 1961 count of 50 (table 1). Additional data 

 are shown in tables 7, 12, 13, and 14. Maxi- 

 mum day's count of 70 fish occurred on 

 September 27 (table 3). In 1961, maximum 

 day's count of 8 fish occurred on October 4. 

 The first coho salmon appearing at Rock 

 Island Dam in 1962 was observed 14 days 

 prior to the initial count of this species of 

 salmon in 1961. Of the coho salmon passing 

 the dam in 1962, 77.3 percent utilized the left 

 ladder, while 3.9 and 18.8 percent ascended 

 the middle and right ladders, respectively. 



