SUTHERLAND: DISTRIBUTION OF STEELHEAD TROUT 



of steelhead trout. Summaries of the data are 

 presented in Figures 1-4 to show the relative 

 abundance of steelhead trout throughout their 

 ocean range by season, as measured by the 

 fishing effort (number of sets) and the catch per 

 set within INPFC statistical areas (2° lat. by 

 5°long.). Appendix Figures 1-15 show in 

 detail the fishing stations, locations where steel- 

 head trout were caught, and the number caught 

 at each location by all vessels. 



km (195 miles) north of Buldir Island, and the 

 other by NMFS in a set about 167 km (90 miles) 

 north of Amchitka Island. None was caught by 

 FRI in many sets in Aleutian Islands passes, 

 along the north side of the islands, or in Bristol 

 Bay. 



Steelhead trout apparently do not occur in the 

 Sea of Japan; none was caught by the Fisheries 

 Agency of Japan in 3 yr of operations in that 

 area. 



Oceanic Distribution 



The oceanic range of steelhead trout as 

 revealed by the catch and effort data extended 

 generally north of lat. 42 °N (the approximate 

 southern limit of effort) from the coast of 

 North America to about long. 152 °E in the 

 western North Pacific Ocean and Okhotsk Sea. 

 The northern limits were about lat. 60 °N in the 

 Gulf of Alaska, lat. 56°N in the Bering Sea, 

 and lat. 53 °N in the Okhotsk Sea. The trout 

 were not uniformly dispersed over this range, 

 however. Broad areas of concentration and 

 seasonal shifts of the population were revealed 

 by the data. 



The Japanese reported catches of 10 steel- 

 head trout in 3 of 6 yr of fishing in the Okhotsk 

 Sea off southwest Kamchatka, USSR. The 

 catches each year were made in the summer 

 near the mouths of productive salmon streams. 

 The time and place of capture suggest that the 

 fish originated in those streams and were either 

 seaward migrants or returning adults. Other 

 information suggests they may have originated 

 elsewhere. By virtue of the similarity of S. 

 gairdneri to S. mykiss, mentioned previously, 

 the Japanese report of steelhead trout in the 

 Okhotsk Sea may be in error. It is not entirely 

 unlikely, however, that steelhead trout of North 

 American origin migrate to the Okhotsk Sea, 

 for west Kamchatkan chum salmon stocks are 

 known to range to long. 152 °W in the central 

 North Pacific Ocean. 



Steelhead trout catches in the Bering Sea 

 were negligible. Extensive salmon fishing by 

 the Fisheries Agency of Japan, NMFS, and FRI 

 over a period of several years resulted in catches 

 of only two steelhead trout. One was caught in a 

 set by the Fisheries Agency of Japan about 361 



Seasonal Abundance 



The catch and effort data showed a definite 

 seasonal shift of steelhead trout. In the winter 

 (Figure 1) they were not caught north of lat. 

 57°N in the eastern Gulf of Alaska, and the 

 northern limit decreased in latitutde diagonally 

 across the Gulf of Alaska to lat. 45 °N in the 

 central North Pacific Ocean and lat. 42°30'N 

 in the western North Pacific Ocean. The latter 

 limit was based on a single fish caught by the 

 Japanese in late winter (April). To the south, 

 catches were made westward from the coast of 

 Oregon along approximately lat. 42 °N to the 

 location of the Japanese steelhead trout catch 

 (long. 157°E, lat. 42°30'N). The greatest con- 

 centration of steelhead trout appeared to be 

 between lat. 44 °N and 52 °N from the coasts of 

 British Columbia, Washington, and Oregon to 

 long. 155 °W. Within this area the catch 

 averaged 2.4 steelhead trout per set and was 

 more than 10 steelhead trout per set in two sub- 

 areas. In all other areas combined, the catch 

 averaged slightly less than 0.04 steelhead trout 

 per set. 



Because of restricted vessel operations in the 

 winter, the true distribution of steelhead trout 

 may differ from that revealed by the catch data. 

 Steelhead trout tagged in the eastern North 

 Pacific Ocean and Gulf of Alaska were recovered 

 as far south in the eastern North Pacific Ocean 

 as California (lat. 36°30'N) in the winter. 

 Similar information was not available on the 

 movement of steelhead trout in the western 

 North Pacific. 



The northward and westward movement of 

 steelhead trout evidently begins in late winter 

 and early spring, for they were well dispersed 

 throughout the Gulf of Alaska and across most 



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