FISHERY BULLETIN: VOL. 86, NO. 2 



In general, the legal size limits increased from 

 north to south, which could result in more recov- 

 eries of juvenile coho salmon in northern than 

 southern regions. Thus, these data do not provide 

 evidence that a large proportion of juvenile coho 

 salmon from British Columbia and waters to the 

 south made northward migrations into Alaskan 

 waters before or during the commercial and 

 sports salmon seasons. Movements of Washing- 

 ton, Columbia River, and Oregon fish into British 

 Columbian waters were common however. 



Hunter (1985) expanded the catches of CWT 

 juvenile coho salmon caught along the west coast 

 of North America during 1978-80 to the total 

 landed plus estimated "drop-off' mortality (fish 

 that were hooked and died without being landed) 

 of both tagged and untagged hatchery groups. 

 Calculations of the percentage returns from dif- 

 ferent release and recapture areas are similar to 

 ours (Table 6). The highest percentage of returns 

 were from the areas of release for all areas except 

 for California, and a higher proportion of the 

 catches of Washington coastal, Puget Sound, Co- 

 lumbia River, and Oregon coastal stocks were re- 

 ported north than south of the area of release. 



Are Juvenile Coho Highly Migratory? 



Based on our observations on movements of 

 marked fish, north-south and seasonal trends in 

 abundance and size, and directional purse seine 

 sets during the summer, we conclude that many 

 juvenile coho salmon from Oregon and Washing- 

 ton coastal streams and the Columbia River are 

 transported by currents to the south in May and 

 June but then migrate north later in the summer. 

 The mean catches per set of yearling coho salmon 

 in August and September are a large fraction of 

 those in June, indicating that in the years studied 

 many juvenile coho salmon in coastal waters of 

 Oregon and Washington were not highly migra- 

 tory. Moreover, more marked juvenile hatchery 

 coho salmon were caught in ocean fisheries in the 

 region of release than in distant waters. Recover- 

 ies of juvenile coho salmon released from hatch- 

 eries south of Cape Flattery were rare in northern 

 waters off Alaska and relatively few were recov- 

 ered in British Columbia (Table 6). In addition, 

 the positive correlation between upwelling off Or- 

 egon and survival of hatchery coho salmon from 

 the Columbia River, Oregon, and California 

 (Nickelson 1986) also argues for a close coupling 

 of OPI coho salmon with a local, not a distant, 

 environmental event during the time that year- 



class survival is determined. All of these trends 

 suggest that most juvenile coho salmon from this 

 area are not highly migratory and that many usu- 

 ally remain in coastal waters near their sites of 

 ocean entry during their first summer in the 

 ocean, and perhaps during their entire ocean life. 

 In years of unfavorable ocean conditions, how- 

 ever, movements may be more extensive or mor- 

 tality may be higher, as suggested by the very low 

 catches of juvenile coho salmon in purse seine sets 

 south of Cape Flattery during September 1983, 

 the year of the recent strong El Nino. 



Although Pacific salmon are renown for their 

 long foraging migrations in the subarctic Pacific, 

 coho salmon demonstrate both nonmigratory and 

 highly migratory behavior. Milne (1950) found 

 immature coho salmon almost year-round in 

 Georgia Strait and concluded that two types of 

 coho salmon exist in British Columbia waters: 

 "ocean" and "inshore" types, the "ocean" type 

 spending most of its ocean life in coastal and off- 

 shore waters and the "inshore" type in inside 

 waters such as Georgia Strait. Healey (1978) 

 caught "inshore" juvenile coho salmon in purse 

 seines in Georgia Strait during summer, fall, and 

 winter months. Similarily, large numbers of coho 

 salmon originating from streams of Puget Sound 

 remain in the Sound throughout their marine life 

 (Haw et al. 1967). Young coho salmon have also 

 been found in the winter and spring, many 

 months after seawater entry in Yaquina Bay 

 (Myers 1980) and other Oregon estuaries 

 (J. Nicholas^). Hartt and Dell (1986), in their im- 

 pressive study of juvenile salmonids of the north- 

 eastern Pacific during 1956-70, recognized these 

 two migratory patterns of coho salmon. They 

 found juvenile coho salmon in waters off Vancou- 

 ver Island and in the Strait of Juan de Fuca 

 throughout the summer and fall, and concluded 

 that some coho salmon spend their entire marine 

 life in "inside" waters and make only limited 

 ocean migrations. 



What Proportion of Juvenile Coho 



from Oregon and 



Washington Migrate North? 



The tagging experiments reported by Hartt and 

 Dell (1986) and Godfrey (1965) provide convinc- 

 ing evidence for long-distance migrations of coho 



■IJ. Nicholas, Oregon Department of Fish and Wildlife, Cor- 

 vallis, OR, 97331, pers. commun. May 1986. 



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