FISHERY BULLETIN: VOL. 72, NO. 2 



ecN 



SS'N 



SCN 



45°^ 



40°N 



I65°W 



155° W 



55''W 



Figure 6. — Distribution of age .1 sockeye salmon from winter catches in the northeastern Pacific Ocean in relation to 



defined oceanographic features. 



is possible that other surface conditions may have 

 greater bearing on the distribution and move- 

 ments of salmon. 



Examination of surface water temperatures in 

 relation to winter catches of age .1 sockeye 

 (Figure 5) revealed that the largest catches 

 were in the temperature range of 3.5° to about 

 5.5°C. The young fish were not generally taken in 

 the extremes of cold or warm surface waters. 

 This was clearly illustrated in 1965 by sampling 

 near long. 170°E. Only a single age .1 sockeye 

 was taken between long. 165^ and 170°E in surface 

 water temperatures of l.S'^C. No fish were caught 

 at other stations where surface temperatures 

 ranged from l.G'' to 2.4°C. Areas in the Bering 

 Sea, where age . 1 sockeye were caught, generally 

 had surface temperatures of S^C or more. The 

 low surface water temperatures or the subsequent 

 reduction in abundance of food forms may cause 

 age .1 sockeye to move out of the Bering Sea 

 and seek warmer water in the North Pacific 

 Ocean. The highest water temperature at which 

 age .1 fish were taken was G.S'C. 



By April and May the age .1 sockeye salmon 

 reach their southernmost limits of distribution 

 (Figure 7). Japanese research vessels caught 

 relatively large numbers of age .1 sockeye in 

 gill nets from lat. 44° to 46°N along long. 175°W 

 illustrating their occurrence south of the central 



Aleutian Islands. Samples taken in 1969 were 

 composed of about 70% age 2.1 fish, which was 

 comparable to the age composition of age .1 

 sockeye salmon taken south of Adak Island that 

 same summer in purse seines by the Fisheries 

 Research Institute (79% age 2.1). 



A few age .1 sockeye salmon were taken in 

 early May 1968 by a Japanese research vessel 

 along long. 175°E (Figure 7). The small sample 

 of readable scales (10 fish) was 50% age 2.1, 

 40% age 3.1, and 10% age 1.1. This was quite 

 unlike the age composition of age .1 sockeye 

 caught south of Adak Island during summer 1968 

 by the Fisheries Research Institute (71% age 1.1 

 fish), indicating that the immature sockeye along 

 long. 175°E in early May might have been Asian 

 fish. 



In the northeastern Pacific, sampling with gill 

 nets along long. 165°W in the spring of 1969 

 resulted in small catches of age .1 fish as 

 far south as lat. 46°N, the limit of sampling. 

 Longline fishing surveys provided some data on 

 the distribution of age .1 sockeye salmon to the 

 east of long. 165°W. 



During 1964, 1965, and 1966, longline surveys 

 by the Fisheries Research Institute (FRI) were 

 made in the northeastern Pacific including the 

 Gulf of Alaska to obtain salmon for tagging. 

 Although longline gear is not considered as 



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