FISHERY BULLETIN: VOL. 72, NO. 2 



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Figure 8. — Catches of age .1 sockeye salmon in the northeastern 

 Pacific (in numbers offish) with longline gear, 1964-66. Data 

 are total catches not weighted for effort. 



Longline sampling also indicated northward 

 movement of the age .1 sockeye in the north- 

 eastern Pacific (Figure 8). The sample of 11 fish 

 caught south of Kodiak Island near long. ISO'^W 

 and lat. 54''N were all taken in 1964 and were 

 all age 2.1 fish; possibly these results indicate 

 the presence of Bristol Bay immature stocks in 

 this area in June. 



Second Year at Sea 

 Immatures Age .1 (July-December) 



In the summer, July-September, the distribu- 

 tion and migration of immature sockeye salmon 

 south of the Aleutian Islands has been well 

 documented (Hartt, 1962, 1966; French, 1964; 

 French, Craddock, Bakkala, Dunn, and Thorson, 

 1967; Royce et al., 1968; Bakkala, 1971; Roths- 

 child et al., 1971). 



An example of the distribution in late July 

 is shown in Figure 9. This typifies the distribu- 

 tion of immature sockeye salmon south of the 

 Aleutians in July and August; the relative abun- 



dance of immatures is usually highest in late 

 July or early August and at lower levels in early 

 July and late August. 



It has also been demonstrated that Bristol Bay 

 stocks predominate south of the central Aleutian 

 Islands by coastal tag returns 1 or 2 yr later 

 and by the relation between age composition and 

 abundance at sea and by the age composition 

 and abundance in the Bristol Bay run 1 yr later 

 (Ossiander, 1965; Rogers, 1970). Based on the 

 limited tag returns from other areas south of the 

 Aleutians and on the abundance of immatures in 

 these waters, we surmise that Bristol Bay sockeye 

 salmon predominate south of the entire Aleutian 

 Islands chain. 



Considerable evidence has been produced which 

 indicates that migration of immature sockeye 

 south of the Aleutian Islands in summer is 

 predominantly westward (Hartt, 1962, 1966; 

 Larkins, 1964; Dunn, 1969); tagging studies have 

 indicated that this westward migration for some 

 fish is rapid and extensive (Royce et al., 1968). 

 This evidence implies that the total population of 

 Bristol Bay immature sockeye salmon shifts to the 

 west or northwest during the summer. Royce 

 et al. (1968) describe this migration as ". . . they 

 migrate westward south of the Aleutian 

 Islands in a more or less continuous band, from 

 late June through mid-September." This ap- 

 parent movement further implies that the east- 

 ward extent of the Bristol Bay population may 

 also shift to the west through the summer. We 

 have not found evidence, however, that waters 

 to the south of the eastern Aleutian Islands and 

 Alaska Peninsula become devoid of Bristol Bay 

 fish during the summer. Rather, it appears that 

 the Bristol Bay population of immatures main- 



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Figure 9. — Distribution of immature sockeye salmon, 21-31 

 July (from Bakkala, Figure 12, 1971). 



598 



