SUTHERLAND: DISTRIBUTION OF STEELHEAD TROUT 



Table 3. — Catch of steelhead trout and catch per purse seine and longline set by research vessels of the 



Fisheries Research Institute, University of Washington, 1956-67. 



French (1964) found the efficiency of the two 

 gears differed with size offish. The purse seines 

 caught relatively more small fish and the gill 

 nets relatively more large fish. The difference in 

 steelhead trout catch per set for purse seines 

 compared to gill nets or longlines may be 

 attributed to the ability of the large fish to 

 escape the purse seines or the lesser chance 

 that the relatively scarce steelhead trout had in 

 encountering the purse seine with its limited 

 coverage in time and space. Because of the 

 bias in the catch data previously discussed and 

 the vast difference in dates and locations of 

 fishing, the catch per set may be of little 

 comparative value between gears. 



Japanese Research Vessels 



The Fisheries Agency of Japan has engaged 

 in fisheries research on the high seas for INPFC 

 since 1955. The research centered chiefly in 

 the western North Pacific Ocean from the Asian 

 coast eastward to long. 180° and from lat. 

 40°N northward to the Aleutian Islands. In 

 some years the investigations extended east- 

 ward along the Aleutian Islands to about long. 

 160°W and throughout most of the Bering and 

 Okhotsk Seas and the Sea of Japan. 



The research during 1955-61 was of about 

 the same intensity as that of NMFS, with one 

 to three vessels operating over a wide ocean 

 area. Fishing effort was substantially increased 

 in subsequent years, with 16 to 19 vessels 



given research assignments primarily in the 

 Japanese land-based fishery area west of long. 

 170 °E and south of lat. 48 °N. Before 1967 

 the vessels were operated only in the spring 

 and summer: April or May to August. In 1967 

 the operations began in early February and 

 ended in late August. 



Catches of steelhead trout by Japanese 

 research vessels were few in all years and in all 

 areas surveyed. The data show a 9-yr total 

 catch of 186 steelhead trout — 171 by gill nets 

 and 15 by longlines (Table 4). The catch per 

 set for the 9 yr averaged 0.048 fish by gill nets 

 and 0.007 by longlines. The apparent abun- 

 dance of steelhead trout in relation to salmon 

 was very low in the areas fished, as indicated 

 by the catch ratios in Table 1. In 9 yr of fishing 

 directed toward salmon, the catch of salmon 

 exceeded steelhead trout in gill nets by an 

 average ratio of 13,743:1 and in longlines by a 

 ratio of 49,632:1. 



Canadian Research Vessels 



Gill net catches of steelhead trout by FRBC 

 were not included in the catch data submitted 

 to INPFC before 1960. A single steelhead 

 trout was reported in 1960, and some were 

 listed in 1963 catch data from inshore sets. 

 FRBC began longline fishing in 1961 to catch 

 live fish for tagging experiments; steelhead 

 trout as well as salmon were included in their 

 catch reports. 



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