FRENCH and BAKKALA: NEW MODEL OF OCEAN MIGRATIONS 



of about lat. 51^N compared to catches south of 

 this latitude. It appears, therefore, that the young 

 salmon migrate through passes between long. 

 169°W and 179^E (the area bordered by Umnak 

 Island on the east and Amchitka Island on the 

 west) and then move eastward. A possible path- 

 way from the Bering Sea to the North Pacific may 

 be Amchitka Pass where a branch of the Alaskan 

 Stream in September flows northward into the 

 Bering Sea (Favorite and Ingraham, 1972). 



Depending on routes followed, the migration 

 from the eastern Bering Sea to the central North 

 Pacific near lat. 46''N or south of the Alaska 

 Peninsula between lat. 48^ and Sl'^N would 

 require migrations of from about 700 to 1,000 

 miles (1,300-1,850 km) and travel rates of at 

 least 8 to 10 miles (14.8-18.5 km) per day. This 

 rate is entirely reasonable for it has been esti- 

 mated that juvenile salmon travel about 10 miles 

 (18.5 km) per day in the Gulf of Alaska (Royce 

 et al., 1968). 



Salmon research cruises have also included 

 oceanographic studies which have defined major 

 oceanographic features of the Subarctic North 

 Pacific (McAlister et al., 1970). These are perma- 

 nent features of the Subarctic Region and are 

 defined by surface and subsurface characteristics 

 (generally between 100 and 400 m). Salmon 

 catches have been related to these features in 

 an attempt to determine their influence on distri- 



bution and movements of salmon. Bakkala (1971) 

 related winter catches of age .1 sockeye salmon 

 in 1962, 1963, 1965, and 1967 to the major water 

 masses and indicated that the salmon were usu- 

 ally associated with the Oyashio Extension Area 

 (Figure 5). 



Catches in winter 1969 and 1970, however, 

 show that the age .1 fish were not always 

 associated with this water. The eastward-moving 

 water between the Ridge and Transition Areas 

 was previously separated into Oyashio and Sub- 

 arctic Current Areas, but more recent termi- 

 nology combines the two areas into a single 

 feature called the Western Subarctic Intrusion 

 (Favorite, Ingraham, and Fisk, 1972). In Figure 6 

 are shown four years of winter catch data and 

 associated oceanic features in the northeastern 

 Pacific. In 1962 and 1967, age .1 fish were 

 associated with the Western Subarctic Intrusion. 

 In 1969 and 1970, this water mass shifted 

 northward (in 1970 it formed only a relatively 

 narrow tongue stretching east of long. 160'' W) but 

 was not accompanied by a corresponding shift in 

 distribution of the age .1 sockeye salmon. These 

 fish remained at much the same latitudes as in 

 the earlier years, and their winter distribution 

 was not affected by changes in location of the 

 specific water mass. Because this particular water 

 mass is defined by weak eastward flow and 

 temperature conditions between 200 and 400 m, it 



I70°E 



180 



I70°W 



I60°W 



I50°W 



Figure 5. — Distribution of age .1 sockeye salmon in the winters of 1962, 1963, 1965, and 1967 

 in relation to oceanographic features of the Subarctic Region of the North Pacific Ocean. 



595 



