86 



Fishery Bulletin 92(1), 1994 



July 1984 



August 1984 



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Pink Chum Sockeye Coho 



Pink Chum Sockeye Coho 



Salmon species 



Figure 5 



Catch per unit of effort (CPUE) and frequency of occurrence of 

 juvenile salmonids (pink, Oncorhynchus gorbuscha; chum, O. keta; 

 sockeye, O. nerka; coho, O. kisutch) in the outside waters (69 sets), 

 outer coast inlets (18 sets), and inside waters (55 sets) in South- 

 east Alaska in July and August 1984. Note change in scale of 

 CPUE from July to August 1984. 



Juvenile salmon migrations along the Pacific coast 

 in 1984 did not peak off Southeast Alaska until, at 

 earliest, August. In July, CPUE's were much higher 

 in the outside waters of British Columbia than in 

 Southeast Alaska. By August, CPUE of juvenile 

 salmon in outside waters of Southeast Alaska had 

 increased fivefold, and FO had increased for each 

 species. Hartt and Dell (1986) observed that juve- 

 nile salmon abundance peaked in August in outside 

 waters of Southeast Alaska. 



In Southeast Alaska, juvenile sockeye salmon 

 probably begin their ocean migration to the Gulf of 

 Alaska before juvenile pink and chum salmon, based 

 on two observations from our study. First, the sock- 

 eye salmon did not occur in protected waters along 

 the outer coast of Southeast Alaska like the other 

 species: no sockeye salmon were captured in an 



outer coast inlet. Second, sockeye 

 salmon was the only species with a 

 higher CPUE in outside waters than in 

 inside waters. This higher abundance 

 outside, coupled with low abundance in 

 inside waters in July and August, is 

 consistent with the conclusion that 

 sockeye salmon commence their ocean 

 migration before pink or chum salmon 

 (Straty, 1981; Healey, 1982). 



The migration of pink salmon from 

 the inside waters of Southeast Alaska 

 lasts until at least September. Martin 

 (1966) concluded that late July and 

 early August were the peak periods of 

 juvenile pink salmon migration from 

 the inside waters. However, our data 

 show that pink salmon abundance in 

 inside waters increased from July to 

 August and that pink salmon were 

 more abundant in inside waters than 

 outside waters in August, thus indicat- 

 ing that migration out of the inside 

 waters was not complete in August. 

 The seasonal migration of juvenile 

 chum salmon out of Southeast Alaska 

 could not be determined from the abun- 

 dance data of this study. The migration 

 of juvenile pink, chum, and sockeye 

 salmon out of the inside waters in Sep- 

 tember and later has not been studied. 

 The offshore migration of coho 

 salmon in Southeast Alaska is more 

 complex. CPUE and FO of coho salmon 

 in inside waters remained relatively 

 constant for July and August. Coho 

 salmon was the only species with both 

 a higher CPUE and FO in inside wa- 

 ters than in outside waters in August. These data 

 suggest extensive residency in inside waters for a 

 substantial portion of coho salmon juveniles in 

 Southeast Alaska. Other researchers have found 

 that some juvenile coho salmon remain in the east- 

 ern Pacific Ocean inside waters until late fall 

 (Healey, 1984; Hartt and Dell, 1986; Orsi et al., 

 1987). Winter residency of juvenile coho in inside 

 waters of Southeast Alaska is apparently rare. 2 

 Hartt and Dell ( 1986) and Pearcy and Fisher ( 1990) 

 also found coho salmon offshore as early as May or 

 June; Hartt and Dell ( 1986) noted that juvenile coho 

 salmon migrated seaward earlier than the other 

 salmon species, presumably because of their larger 



2 J. A. Orsi, Auke Bay Laboratory, L1305 Glacier Highway, Ju- 

 neau, AK 99801-8628. pers. commun. Jan. 1992. 



