SCARXECCHIA and WAGNER CONTRIBUTION OF COHO SALMON TO OCEAN SPORT FISHERY 



and 63 at Brookings/Gold Beach. An estimated 

 75% of all coho salmon landed by the entire sport 

 fishery from mid-June to mid-September 1977 

 originated from hatchery releases. Percentages of 

 hatchery coho salmon by port and period, along 

 with confidence intervals, are shown in Table 6. 

 Since the sport fishery is mainly composed of 

 private and charter boats on day-long trips, our 

 estimated percentages of hatchery and wild fish by 

 port probably reflect fairly well the actual per- 

 centages occurring near each port, assuming simi- 

 lar catchability of hatchei-y and wild fish. 



DISCUSSION 



Of the estimated 140,660 coho salmon caught in 

 the ocean in 1977 by Oregon sport fishermen from 

 mid-June to mid-September, 35,300 were wild 

 fish. Although scales from fish caught by the com- 

 mercial troll fishery were not analyzed in 1977, it 

 is likely that the overall percentages of wild and 

 hatchery fish were similar to those of sport fishery. 

 To evaluate this likelihood, we compared observed 

 percentage of marked fish in the monthly catch of 

 the sport fishery for six Oregon ports with the 

 percentage of marked fish in the corresponding 

 commercial catch. In only 7 of the 18 comparisons 

 for which sample sizes were adequate did percent- 

 ages of marked fish caught in a given strata by the 

 sport fishery differ from those of the commercial 

 fishery (P<0.05), which indicates that overall per- 

 centages of hatchery and wild fish are similar for 

 the two fisheries. 



We can explain the north to south trend toward 

 increasing percentage of wild fish in the catch 

 (Table 6) by assuming a northward movement of 

 hatchery and wild coho salmon as the season pro- 

 gresses, as Van Hyning (1951) concluded, with 

 wild fish from south and north coastal streams 

 ceasing their northward movement near their 

 natal streams. Since over 80% of the coho salmon 

 produced by hatcheries in California, Oregon, and 

 Washington ( excluding Puget Sound ) are released 

 in the Columbia River and its tributaries (Oregon 

 Department of Fish and Wildlife see footnote 7), 

 many of the hatchery fish off the Oregon coast are 

 probably headed for the Columbia River. These 

 hatchery fish continue northward and concentrate 

 near the mouth of the Columbia River. The argu- 

 ment for south to north movement of coho salmon 

 is supported by the occurrence of lower percent- 

 ages of hatchery fish late in the fishing season in 

 catches off of Garibaldi, Depoe Bay, Newport, and 



Winchester Bay (Table 6). Late in the season, 

 hatchery fish may be proportionately less abun- 

 dant along the south and central coast, since most 

 Columbia River fish would have moved northward 

 by this time, leaving mostly coastal hatchery and 

 wild fish contributing to the south and central 

 coast fisheries. The lowest percentage of hatchery 

 fish noted was 49.7 at Winchester Bay, from 1 

 August to 15 September. 



Another possible factor contributing to lower 

 percentage of hatchery coho salmon in the fishery 

 to the south is that a substantial portion of adult 

 hatchery fish released as smolts from Columbia 

 River hatcheries do not migrate far southward 

 along the Oregon coast. The argument is sup- 

 ported by the large number of coho salmon caught 

 per angler day at Hammond early in the fishing 

 season (Table 5), perhaps indicating that coho 

 salmon returning to the Columbia River are con- 

 centrated near the river in early summer. The 

 high percentage of hatchery fish caught at Ham- 

 mond from 16 June to 15 July further supports this 

 hypothesis (Table 6). 



The total catch of coho salmon and catch per 

 angler day were low after mid-August 1977 from 

 Winchester Bay southward, and were low for all 

 ports after August (Table 5), so that while the 

 percentage of wild coho salmon caught rose late in 

 the season, the numbers caught were low, espe- 

 cially along the southern coast. Closing the season 

 for salmon fishing after mid-August would not 

 have protected many wild coho salmon, and would 

 have made only a small sacrifice in catch of hatch- 

 ery fish. Almost twice as many chinook salmon, O. 

 tshawytscha, would have been lost to the sport 

 fishery. 



Combined data obtained from the Oregon De- 

 partment of Fish and Wildlife from Winchester 

 Bay to Brookings from mid-August to mid- 

 September showed that an estimated 1.8 chinook 

 salmon were caught for every coho salmon landed 

 by sport fishermen. During years of higher abun- 

 dance of coho salmon, fishermen may tend to fish 

 more for coho and less for chinook salmon than 

 they did in 1977, which would increase fishing 

 pressure on wild stocks of coho salmon late in the 

 season. 



If wild and hatchery fish are distributed differ- 

 ently in oceanic areas, fishing pressure could be 

 adjusted to meet management goals. If, however, 

 there is substantial variability in the localities of 

 capture of wild fish, either because of the fishery or 

 because of environmental factors, and if hatchery 



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