FiousE 9. — Diagram of probable ocean migrations of pink 

 salmon stocks originating in East Kamchatka. 



Figure 10. — Catclies of .1-age .sockeye salmon during win- 

 ter gill netting in 1962 and 1963 (source: French and 

 Mason, 1964). 



a-s .1-age ' immature fish of 35-cm. average length 

 migrating westward in large numbers along the 

 south side of the Aleutian Islands. Two items of 

 indirect evidence, however, help fill in the first 

 year's migration. Fii-st, the Bristol Bay sockeye 

 salmon apparently do not migrate south of the 

 Aleutians during their first summer; .0-age juve- 

 niles were extremely rare in the intensive purse 



" Ocean age designation throughout this paper Is that proposed 

 by Koo (1962) in which the number of ocean winter annul! on the 

 sculo Is preceded hj- a decimal i)oint (e.g.. .1-agc — one winter iit 

 sea). 



seine sampling along the south side of the Aleu- 

 tians during the summers of 1956-65 (Interna- 

 tional North Pacific Fisheries Commi.ssion, 1957- 

 66). Second, winter sampling with gill nets 

 (French and Mason, 1964) has shown the presence 

 of .1-age sockeye salmon north of the western 

 Aleutians and south of the central Aleutians dur- 

 ing January and February' (fig. 10). At this stage 

 they average alx)ut 25 to 30 cm. long. It has not 

 been proved that these are Bristol Bay fish, but it 

 seems safe so to assume, because of their abundance 

 and because tagging and other studies have shown 

 that Bristol Bay stocks predominate in these areas 

 in spring and summer. Thus, we may [lostulate that 

 the fingerlings remain in the Bering Sea at least 

 until autumn, and their winter distribution sug- 

 gests that tliey reach the western Bering Sea and 

 proceed soutlnvard into the Xorth Pacific. The next 

 move must be eastward in the Subarctic Current to 

 place them in position by late spring to make the 

 cliaraeterifttic vsummer migration westward with 

 the Alaskan Stream along the south side of the 

 Aleutian Islands — a migration which has been ex- 

 tensively studied and described (Hartt, 1966). The 

 postulated first year's migi-ation is diagi-ammed in 

 figure 11 A as part of the schematic of (heir entire 

 ocean travels. The first year's migration could be 

 accomplished at an average rate of 10 miles (18.5 

 km.) i>er day, which is the rate indicated for the 

 juveniles tagge<:l near Kodiak Island in the Gulf of 

 Alaska discussed earlier. 



SECOND YEAR AT SEA 



During their second summer at sea, Bristol Bay 

 sockeye salmon arc immature .1-age fisli averaging 

 35 cm. long. They migrate westward south of the 

 Aleutian Islands in a more or less continuous 

 band, from late June tlirough ini(l-Se))tember. The 

 band extends otr.sliore about 100 miles (185 km.), 

 but the greatest abundance is usually within 30 

 miles (55.6 km.) (French, 1964: Ilartt. 1^66). The 

 fish ai^parently approach from areas to the south 

 and east and continue far westward and north- 

 westM-ard, as .shown by tag returns from the high- 

 seas fleet in tlie year of release (fig. 12). The 

 (loiniiiaiice of Bristol Bay stocks is demonstrated 

 by coastal tag returns 1 year later (fig. 12) and 

 by the relation between age composition and 

 abundance at sea and age composition and abun- 

 dance in the Bristol Bay run 1 year later (Ossi- 

 ander, 1965). Some idea of the magnitude of the 



450 



U.S. FISH AND WILDLIFE SERVICE 



