650 



Fishery Bulletin 101(3) 



ing, 1996). Nonetheless, the extension of a DNA baseline to 

 include populations in Oregon and California, may resolve 

 fine-scale (geographic and temporal) differences between 

 coho salmon populations in southern coastal areas. 



Stock compositions of ocean-caught juvenile 

 coho salmon 



Studies using large purse seines conducted in 1981-85 

 revealed that juvenile coho salmon were the most abundant 

 of the Oncorhynchus species in the nearshore areas along 

 the Oregon and Washington coasts ( Pearcy and Fisher, 1988; 

 1990). Pearcy and Fisher (1988; 1990) captured hatchery- 



tagged juvenile coho salmon and concluded they were not 

 highly migratory, often remaining close to their point of sea 

 entry for several months. Our genetic results corroborate 

 that finding. Genetic estimates indicate that about 89% 

 of ocean juveniles caught in June and 81% in September 

 originated from the Columbia River and adjacent coastal 

 rivers. Recoveries of hatchery-tagged fish in=41) also indi- 

 cate that juveniles remain near river mouths in their first 

 few months after ocean entry; only three of these CWT- 

 marked fish came from hatcheries in other regions. 



However, our genetic results indicate that a change has 

 occurred in the distribution of Washington coastal and 

 Puget Sound juvenile coho salmon. In the 1980s, juvenile 

 coho salmon from Washington coastal hatcheries were 

 not recovered along the Washington and Oregon coasts 

 after mid summer, apparently having migrated northward 

 (Pearcy and Fisher, 1988). Pearcy and Fisher (1990) also 

 found that Puget Sound coho salmon did not migrate along 

 the Washington and Oregon coast until sometime between 

 their first and second summer at sea. However, our genetic 

 results showed that in 1998-2000 fish from Washington 

 coastal streams and hatcheries comprised substantial 

 proportions of the juveniles in nearshore areas along 

 the Washington and Oregon coast in both early and late 

 summer (24% and 28%). We also found that juvenile coho 

 salmon from Puget Sound are present in late summer. Our 

 finding that coho salmon from northern stocks move south 

 along the coast during their first summer was substanti- 

 ated by the catch of CWT-marked fish originating from 

 Puget Sound (n=2) and southern British Columbia {n=2). 



Recent reductions in the number of coho salmon smolts 

 released from the region's hatcheries have not resulted in 

 a decrease in the proportion of hatchery juveniles along the 

 Oregon and Washington coasts. Annual releases of hatch- 



