FRENCH and BAKKALA: NEW MODEL OF OCEAN MIGRATIONS 

 A 



1st YEAR AT SEA ( JULY- MAY) 

 AGE TO AGE 1 



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180° 



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2nd YEAR AT SEA 



(JUNE-SEPTEMBER) 



IMMATURE AGE .1 





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55° N 



55° 



OCTOBER -MAY 

 IMMATURE AGE .1 TO AGE .2 



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3rd YEAR AT SEA (JUNE-SEPTEMBER) 

 IMMATURE AGE .2 Migrotion continued as in EftF 



OCTOBER -MAY 

 MATURING AGE I TO AGE 2 



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3fd YEAR AT SEA (JUNE-JULY) 

 MATURING AGE .2 



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Figure 25. — Model of migration of Bristol Bay sockeye salmon. 



The new model calls attention to changes in 

 migration or distribution patterns from year to 

 year — which could affect indices of abundance 

 that are based on data from only one area or time 

 period. 



A graphical illustration of the model appears 

 in Figure 25, and a brief narrative account follows. 



First Year at Sea 



Juveniles Age .0 (July-December) 



Juveniles, age .0 fish, after leaving the rivers 

 of Bristol Bay, move southwest along the north 



side of the Alaska Peninsula, and by mid- 

 September many still remain east of long. leS'^W 

 and within 90 miles (167 km) of shore. In late 

 fall or early winter the juveniles move south- 

 westward along the Aleutian Islands and then 

 proceed south through various passes, most likely 

 between long. 179'E and 169°W. The migration 

 out of the Bering Sea may be motivated by lowered 

 surface water temperatures and reduced food 

 supplies — ^juveniles generally are not found in 

 surface waters with temperatures less than 3^C. 

 Principal routes of migration may be through 

 Aleutian Islands passes where the Alaskan 

 Stream branches into the Bering Sea. 



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