Tabulations of the runs were obtained by 

 adding commercial catches (winter and sum- 

 mer run) below Bonneville Dam to the counts 

 of fish that pass Bonneville Dam (U.S. Army 

 Corps of Engineers, 1966). The winter-run 

 commercial catch averages only about 3 per- 

 cent of the minimum run. Steelhead trout are 

 seldom caught in the ocean by trolling gear. 

 Thus, the portion of the total run not accounted 

 for in figure 1 is the escapement (magnitude 

 unknown) to tributaries below Bonneville Dam 

 and the catch by the sport fishery in the trib- 

 utaries and the winter-run sport catch in the 

 main Columbia River. 



The sport fishery is large; the average an- 

 nual catch below Bonneville Dam was estimated 

 at 89,000 fish for 1962-66. The average esti- 

 mated sport catch in the Columbia River and 

 its tributaries for 1962-66 was 117,000 summer- 

 run fish and 62,000 winter-run fish (table 4). 



In Idaho, the Salmon, Clearwater, and lower 

 and middle Snake Rivers are the only streams 

 that support runs of steelhead trout. Passage 

 above Oxbow Dam was discontinued in 1964; 

 all spawners are collected at Hells Canyon Dam 

 and routed to hatcheries. Spawning and fish- 

 ing areas eliminated by blockage at Hells Can- 

 yon Dam were the Payette, Weiser, Boise, and 

 Snake Rivers. The size of the sport catch re- 

 flects to a degree the size of the spawning 

 escapement to each tributary, though adverse 

 fishing conditions result in a greater escape- 

 ment in some years than in others and some 

 fish are caught in wintering areas such as that 

 below McNary Dam. Steelhead trout are not 

 easily seen during spawning because they 

 spawn during high water; consequently the 

 number of spawners are not known. 



Future of Steelhead Trout Runs 



Most tributaries of the Columbia River are 

 not overpopulated by steelhead trout spawners 

 because of the extensive sport catch during the 

 prespawning period, the commercial catch in 

 Oregon, and various adverse factors. A num- 

 ber of hatcheries in the Columbia River Basin 

 propagate steelhead trout and the returns of 

 adult fish from hatchery plants are usually 

 high. The prospect for continuation of steel- 

 head trout runs at about 200,000 to 250,000 

 fish appears good, although some areas have 



been taken from production because steelhead 

 trout failed to pass through the reservoirs. 



COHO SALMON 



Somfe coho salmon enter the mouth of the 

 Columbia River to start their spawning mi- 

 gration in late August, but most of the run 

 enters between mid-September and about mid- 

 November. Young coho salmon invariably 

 remain in fresh water for 1 year before mi- 

 grating to the sea. Most of the young fish 

 make the seaward migration about 18 months 

 after the eggs are deposited in the gravel, feed 

 in the ocean for about 18 months, and return 

 to spawn in their third year. Some, mostly 

 males, mature in their second year, after about 

 6 months in the ocean, and are called "jacks." 

 Jacks are recognized by their small size — 

 generally they are less than about 53 cm. long. 



Three-year-old coho salmon weigh an av- 

 erage of 4.5 kg.; they spawn in the fall, usually 

 within a week after they reach their spawning 

 grounds. As the fish migrate upstream or 

 approach maturity, their silvery appearance 

 changes to deep red (deeper in males). The 

 males develop a hooked nose, curved jaw, and 

 a hump anterior to the dorsal fin; the females 

 may become slightly humped and have slightly 

 curved jaws. 



Coho salmon are prized by sport fishermen 

 because of their ability to put up a hard fight 

 when hooked and their good eating quality. 

 Major sport fisheries are along the coasts of 

 Washington, Oregon, and California and in the 

 Columbia River estuary. The flesh is medium 

 red, and those caught in the ocean are espe- 

 cially delicious. 



Spawning Areas 



Coho salmon spawn predominantly in the 

 tributaries of the lower Columbia River (maps 

 7, 8, and 9). Table 5 gives added information 

 about the streams and runs of this species. 



Coho salmon have been introduced into 

 tributaries of the Willamette River system. 

 Although the first generation of adults has re- 

 turned to spawn and fry have been observed 

 in the streams, it is not yet known whether 

 runs of this species are permanently estab- 

 lished. I have designated the areas where 

 spawning now occurs. 



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