SUTHERLAND: DISTRIBUTION OF STEELHEAD TROUT 



head trout fishery in California is exclusively a 

 sport fishery. In Oregon and Washington it is 

 open to commercial fishermen. Although in 

 Washington, the commercial fishery is limited 

 to Indians fishing in treaty waters. In British 

 Columbia, where steelhead trout are fished com- 

 mercially, landings have ranged from 59,000 kg 

 (130.000 lb.) to 141,000 kg (310.000 lb.) during 

 1961-67; no i)ronounced trend towards decreas- 

 ing or increasing landings is evidenced (Depart- 

 ment of Fisheries of Canada, 1967). 



Sport fishery catches of steelhead trout have 

 increased substantially in recent years. In 

 Washington, for example, angler catches have 

 increased from an average of approximately 

 137,000 fish during the 1951-52 to 1960-61 

 fishing seasons to approximately 268,000 fish 

 during the 1961-62 to 1965-66 seasons (Wash- 

 ington Game Department, 1968). 



Little has been published about the distribu- 

 tion and biology of steelhead trout in the 

 oceanic environment. Since 1953, Canada, 

 Japan, and the United States, as member 

 nations of the International North Pacific 

 Fisheries Commission (INPFC), have engaged 

 in extensive research in the North Pacific Ocean, 

 Gulf of Alaska, Bering Sea, Okhotsk Sea, and 

 Sea of Japan on species of mutual interest. 

 Their vessel operations have extended over all 

 seasons and to most areas of the North Pacific 

 Ocean and Bering Sea occupied by salmon and 

 steelhead trout. They have included catches of 

 steelhead trout in their reports to the Com- 

 mission (the Canadians and Japanese did not 

 do this in all years), although steelhead trout 

 was not considered a species of mutual interest. 

 In 1955, the Fisheries Research Institute (FRI) 

 began tagging experiments on salmon and steel- 

 head trout in the North Pacific Ocean, Gulf of 

 Alaska, and Bering Sea under contract to the 

 National Marine Fisheries Service (NMFS), 

 formerly the Bureau of Commercial Fisheries. 

 Research reports of FRI that describe these 

 experiments have been included in the reports 

 of investigations by the United States in the 

 Annual Reports of INPFC. Neave and Hana- 

 van (1960) used data from catches by Canadian 

 and United States research vessels in 1956 and 

 1957 to describe the summer distribution of 

 steelhead trout in the Gulf of Alaska and along 



the eastern Aleutian Islands. Larkins (1964) 

 rei)orted steelhead trout as common in gill net 

 catches of NMFS research vessels operating 

 in the Gulf of Alaska, North Pacific, and Aleu- 

 tian Island areas. The occurrence of steelhead 

 trout in the Gulf of Alaska in the winter was 

 noted by Manzer (1968). The purpose of my 

 study was to make additional information 

 available on the life history of steelhead trout in 

 the ocean. Some of this information may be of 

 value in the future in managing the fisheries. 

 For example, steelhead trout are vulnerable in 

 offshore waters to gill net and longline fisheries 

 such as are now carried out by Japan in the 

 western North Pacific Ocean; a gill net or long- 

 line fishery in the eastern North Pacific would 

 probably be a serious threat to some stocks. 



FISHING GEAR AND METHODS 



The fishing gear and methods used aboard 

 research vessels of Canada, Japan, and the 

 United States have been described in various 

 publications. Canadian high-seas fishing was 

 reported in detail by Neave, et al. (1962) and 

 that of Japan was described by the Fisheries 

 Agency of Japan (1962). The methods used by 

 the United States in 1953 in pioneering efforts 

 of the RV J()h)i N. Cobb were reviewed by 

 Schaefers and Fukuhara (1954). Later reviews 

 were made by Powell and Peterson (1957), 

 Hanavan andTanonaka (1959), Hartt (1962), 

 and French (1964). Gill nets, longlines, and 

 purse seines were the types of gear used. 



Gill nets of several mesh sizes, synthetic 

 materials, lengths, and depths were fished by 

 the research vessels in daylight and darkness 

 for various periods. The net string most com- 

 monly used consisted of mesh sizes ranging 

 from 50.8 to 139.7 mm and was constructed of 

 multifilament nylon. It generally varied from 

 about 2,928 to 3,221 m (1,600-1,700 fm) in 

 length and 7.3 to 9.1 m (4-5 fm) in depth. The 

 net string was usually set at dark, allowed to 

 drift free through the night, and hauled after 

 dawn the following morning. 



The basic unit of the longline is a skate 

 (basket) consisting of 49 hooks, one each on 1-m 

 dro]) lines, spaced 2.3 m apart; the total length 

 of the skate is 138 m (75.5 fm). The number of 



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