summer upwelling there is a function of those elements 

 (Hollister 1966), he may have indirectly detected an association 

 between catchability and upwelling. Fall chinook salmon of 

 several age groups comprise the bulk of the ocean catches, so 

 fishing success late in the previous season may indicate abun- 

 dance of some age groups in the following year. All of these 

 factors could be related to ocean fishing success for chinook 

 salmon. 



For those coho salmon stocks where naturally produced fish 

 are a major component, environmental factors have been found 

 to strongly influence recruitment; while in most major produc- 

 tion areas, massive hatchery releases have complicated stock- 

 recruitment relationships in recent years. Low streamflow rates 

 during the year of juvenile freshwater residence reduce survival 

 (Neave 1949; Smoker 1953), and an index of summer flow rate 

 in year i — 2 is used to predict Puget Sound wild coho salmon 

 runs in year i (Zillges 1974, 1977). 



Environmental conditions during periods of preemergence 

 and hatching could also influence abundance. The same ocean- 

 ographic conditions suspected of influencing survival of juvenile 

 chinook salmon and catchability of harvestable fish could also 

 affect coho salmon. Hollister (1956) referred to a positive 

 association between troll success off the west coast of Vancouver 

 Island and surface salinity, Wright et al. (1976) found that peak 

 success in the Oregon troll fishery coincided with surface sea 

 temperatures of 11 °-13°C, Gunsolus (1978) described a positive 

 relationship between abundance of adult coho salmon off 

 Oregon and spring upwelling in the previous year, and Fisheries 

 of Canada (1971) cited an example of the influence of upwelling 

 on trolling activities. Jack returns are considered indicative of 

 survival of a particular year class and may be valid indicators of 

 abundance of maturing Columbia River coho salmon (Gunsolus 

 1978). Growth rate may show a direct relationship with survival 

 in the marine environment (Henry 1961). There may be an in- 

 verse relationship between average individual size and 

 catchability, with smaller coho salmon staying closer to shore 

 and being more vulnerable to the fisheries, an opinion cor- 

 roborated by results of Oregon Department of Fish and Wildlife 

 studies (Gunsolus 1978). All of these diverse elements could af- 

 fect ocean fishing success for coho salmon. 



In this paper, we have examined the relative influence of 1) 

 brood year abundance, 2) hatchery releases, 3) freshwater 

 environmental factors, 4) oceanographic conditions, and 5) 

 levels of nominal effort on a) commercial ocean troll catch, b) 

 troll catch per unit of effort (CPUE), and c) ocean sport catch 

 of pink, chinook, and coho salmon during 1955-75 from 

 Tillamook Head, Ore., to Cape Scott, Vancouver Island. 

 Several predictive models for ocean catch based on the above 

 factors were developed and their reliability evaluated. 



METHODS 



Catch and effort data for commercial fisheries were obtained 

 from Washington Department of Fisheries (1955-75) and 

 Canada Fisheries and Marine Service (1955-75a). Sources of 

 sport fishery data were Haw and Buckley (1965), Nye and Ward 

 (1966), Haw et al. (1967), Washington Department of Fisheries 

 (1966-75), and Canada Fisheries and Marine Service (1955-75b). 

 Hatchery production figures originated from Wahle et al. (1975) 

 and unpublished data (Foster*) of the Washington Department 



of Fisheries, Hatchery Division. Estimates of run size and 

 escapements were from Oregon Department of Fish and 

 Wildlife and Washington Department of Fisheries (1976) for 

 Columbia River stocks, International Pacific Salmon Fisheries 

 Commission (1962, 1968, 1974, 1976) for pink salmon, and 

 unpublished data (Zillges 5 ) for Puget Sound chinook and coho 

 salmon. Average winter air temperatures and river peak 

 momentary discharge rates at Washington stations were obtain- 

 ed from U.S. Geological Survey records, Tacoma, Wash. 

 Surface sea temperatures and salinities at Canadian shore sta- 

 tions were from Hollister and Sandnes (1972), Hollister (1972, 

 1974), and Giovando and Hollister (1974). Indices of upwelling 

 were modified from Gunsolus (1978). Data obtained directly (or 

 slightly modified) from readily available published sources are 

 not reproduced here and can be found in Low (1979). 



The Washington Department of Fisheries and Canada 

 Fisheries and Marine Service used a marine statistical area 

 system to report commercial catches in numbers of salmon by 

 species and effort in either individual vessel landings 

 (Washington) or days fished (Canada) during 1955 through 

 1975. We have pooled data for these areas according to the district 

 classification shown in Figure 1 . Washington data reported by 

 geographical category were classified as follows: 1) Columbia 

 River district: Tillamook Head to Cape Shoalwater; 2) Coastal 

 Washington district: a) Cape Shoalwater to Cape Elizabeth, b) 

 Cape Shoalwater to Cape Johnson, c) Cape Elizabeth to Cape 

 Johnson, d) Split Rock (near Cape Elizabeth), e) Quillayute 

 (zone 3), f) La Push; 3) Puget Sound district: a) Cape Flattery 

 (zone 4), b) Barkley Sound (area 23), c) Swiftsure (area 21). 



'G. Zillges, Washington Department of Fisheries, Olympia, Wash., pers. com- 

 mun. October 1977. 



VANCOUVER IS 

 DISTRICT 



PUGET SOUND 

 DISTRICT 



COASTAL 



WASHINGTON 



DISTRICT 



COLUMBIA 



RIVER 

 DISTRICT 



Warrenton 

 TILLAMOOK HEAD 



'R. Foster, Washington Department of Fisheries, Olympia, Wash., pers. com- 

 mun. February 1976. 



Figure 1. — Salmon statistical catch areas. 



