Figure 23. — Distribution of age .3 sockeye salmon in winter (data from 1962-70 with the exception 



of 1964, 1966, and 1968). 



maturing age .2 fish but is somewhat north of 

 the latter group. We do not know if these fish 

 remain in the Bering Sea throughout winter and 

 early spring. 



By spring, the age .3 sockeye are distributed 

 across the North Pacific Ocean primarily in the 

 Ridge Area and the northern part of the Western 

 Subarctic Intrusion Area waters. Their move- 

 ments toward Bristol Bay in late spring are 

 assumed to be similar to those described for age 

 .2 sockeye. 



INFLUENCE OF WATER AREAS 



AND CURRENTS ON 



SALMON MIGRATIONS 



In the previous sections we have inferred from 

 various research results the migrations of Bristol 

 Bay sockeye salmon from the time they leave the 

 estuary until they return as maturing fish. We 

 have also shown their distribution in relation to 

 water masses which can be summarized as 

 follows: After leaving the Bering Sea, possibly 

 in Alaskan Stream Area water extruding through 

 Aleutian Islands passes, (Favorite and Ingraham, 

 1972), the young salmon move southward in 

 winter through the Alaskan Stream and Ridge 

 Areas into the Western Subarctic Intrusion Area 

 waters. In spring they usually are in Transition 

 waters. In early summer they move northward 



(a reversal of the winter movement) through the 

 Western Subarctic Intrusion Area to Ridge and 

 Alaskan Stream Area waters. Some components 

 of the population move into central and northern 

 parts of the Bering Sea. The salmon that will 

 mature the following spring remain in northern 

 waters, the Ridge Area primarily, over the winter 

 and spring until they commence the spawning 

 migration. Immature age .2 fish repeat the 

 southward movement they made a year earlier 

 and join the new group of age .1 fish. The matures, 

 in late spring, migrate from the Ridge Area and 

 the northern part of the Western Subarctic 

 Intrusion Area waters through the Alaskan 

 Stream and into the Bering Sea through various 

 passes of the Aleutian Islands. 



The influence of these water masses on distri- 

 bution and migrations of sockeye salmon is not 

 evident from our observations. As demonstrated, 

 sockeye salmon in all life history stages appear 

 to move readily in and out of the various water 

 masses. Although salmon at certain life history 

 stages appeared to associate with certain water 

 masses in some years, a shift in location of water 

 masses in other years was not accompanied by 

 a corresponding shift in salmon distribution. 

 Examples of this were shown in Figure 6; in 

 1962 and 1967, immatures were mainly found 

 near or south of lat. 50^N and in the Western 

 Subarctic Intrusion Area; but in 1970 when this 

 oceanographic feature was located north of 50^N, 

 most immatures were in the same general location 



609 



