Abstract. Distribution and 



size during their first summer at 

 sea were determined for juvenile 

 salmon (Oncorhynchus spp.) 

 caught in oceanic waters off north- 

 ern British Columbia and South- 

 east Alaska, and in marine waters 

 within the Alexander Archipelago 

 of Southeast Alaska. More than 

 10,000 juvenile salmon were 

 caught in 252 purse-seine sets 

 during August 1983, July 1984, 

 and August 1984. Distribution was 

 patchy; juvenile salmon were 

 highly aggregated, rather than 

 dispersed randomly. Distribution 

 and size of pink salmon 

 (O. gorbuscha), sockeye salmon (O. 

 nerha), and chum salmon (O. keta) 

 were similar but differed from 

 coho salmon (O. kisutch). Chinook 

 salmon (O. tshawytscha) were ex- 

 cluded from most analyses because 

 few were caught. Sizes were con- 

 sistent with the concept that juve- 

 nile salmon in more northern and 

 seaward locations had been at sea 

 longer than those in more south- 

 ern and inshore locations. Juvenile 

 salmon migration up the Pacific 

 coast did not peak in abundance 

 off Southeast Alaska until August; 

 movement from inside to outside 

 waters was not complete by the 

 end of August. The migration band 

 of juvenile salmon in outside wa- 

 ters of Southeast Alaska extended 

 beyond the continental shelf to at 

 least 74 km offshore, twice the dis- 

 tance previously reported. 



Marine distribution and size of 

 juvenile Pacific salmon in 

 Southeast Alaska and 

 northern British Columbia 



Herbert W. Jaenicke 



Adrian G. Celewycz 



Auke Bay Laboratory, Alaska Fisheries Science Center 



National Marine Fisheries Service. NOAA 



1 1305 Glacier Highway. Juneau. Alaska 99801-8626 



Manuscript accepted 28 September 1993 

 Fishery Bulletin 92:79-90 (1994) 



The general migratory movements 

 of Pacific salmon (Oncorhynchus 

 spp.) during their first year at sea 

 have been described (Hartt and 

 Dell, 1986), but little information is 

 available on the seaward migration 

 of juvenile salmon from the inside 

 waters of Southeast Alaska into the 

 Gulf of Alaska. Salmon moving sea- 

 ward from streams inside South- 

 east Alaska pass first through the 

 complex waterways of the 

 Alexander Archipelago, the "inside 

 waters" of Southeast Alaska. Upon 

 entering the Gulf, these salmon 

 either occupy outer coast inlets or 

 move into exposed outside waters. 

 Salmon entering exposed outside 

 waters either migrate north along 

 the coast or move progressively far- 

 ther offshore (Hartt and Dell, 

 1986). Determining when and at 

 what size juvenile salmon from 

 Southeast Alaska utilize different 

 habitats during their seaward mi- 

 gration to the Gulf may facilitate 

 understanding the high mortality 

 during their first few months at sea 

 (Parker, 1968; Bax, 1983; Furnell 

 and Brett, 1986). 



Our goal was to ascertain the 

 distribution and migration of juve- 

 nile Pacific salmon during their 

 first summer at sea after they 

 leave nearshore estuarine habitats. 



Specific objectives were 1) to deter- 

 mine relative distribution, abun- 

 dance, and size of juvenile salmon in 

 exposed outside waters, in protected 

 waters adjacent to the outer coast, 

 and in the inside waters of Southeast 

 Alaska, and 2) to compare abun- 

 dance and size of juvenile salmon in 

 outside waters of Southeast Alaska 

 and northern British Columbia. 



Methods 



Study area and time 



The study area extended from 

 Lituya Bay, Southeast Alaska, to 

 the northern end of Vancouver Is- 

 land, British Columbia (Fig. 1). 

 Three major habitats were 

 sampled: 1) outside waters (the 

 North Pacific Ocean and Gulf of 

 Alaska adjacent to the outer coast 

 of Southeast Alaska and British 

 Columbia); 2) outer coast inlets 

 (protected waters along the outer 

 coast of Southeast Alaska); and 3) 

 inside waters (marine waters 

 within the Alexander Archipelago). 

 Southeast Alaska was further di- 

 vided at lat. 56°N into a northern 

 and southern region for some 

 analyses. Fishing effort was con- 

 centrated in the northern region of 

 Southeast Alaska (Fig. 1). 



79 



