FISHERY BULLETIN: VOL. 7, NO. 3 



These results are in general agreement with the 

 known timing and composition of steelhead 

 runs on the west coast of North America (With- 

 ler, 1966). Although major stocks of summer 

 and winter steelhead trout are known to spawn 

 in British Columbia streams, little information 

 is available on their comparative abundance. 

 Winter steelhead trout stocks predominate in 

 Washington, Oregon, and California (J. D. 

 Ayerst, Washington Department of Game, pers. 

 comm.). 



The precise timing of arrival or the seasonal 

 composition of the run cannot be judged solely 

 on the basis of the time of catpture \\. coastal 

 streams, however. Some time lapse between 

 arrival and capture is to be expected. Many of 

 the tagged fish returned to British Columbia 

 were recovered before ascending coastal 

 streams; whereas, most of those returned to 

 Washington, Oregon, and California were 

 recovered after ascending coastal streams. 

 Those captured in the summer are presumably 

 summer-run fish that arrived shortly prior to 

 capture. Recoveries in the winter may be either 

 winter runs or summer runs because both spawn 

 in late winter through spring. 



The tag recoveries indicate that, on the 



average, Canadian steelhead trout spend more 



time at sea than do Washington, Oregon, and 



California steelhead trout, as was also shown 



by Withler (1966) in his analysis of the age 



composition of the stocks. (It should be noted, 



however, that my evidence is based on a rather 



small number of fish.) In comparing the time 



that fish recovered in northern spawning 



streams spent at sea with the time that fish in 



southern streams spent at sea, tagged fish 



recovered in May through March are considered 



as belonging to the same spawning run. Of the 



15 tagged steelhead trout (with readable scales) 



recovered in British Columbia, 6 (40% ) were 



age .1 at the time of tagging; 5 (33% ) were age 



.2; and 4 (27% ) were age .3. Of the 22 recovered 



in Washington, Oregon, and California, 17 



(77%) were age .1 at the time of tagging, and 5 



(23%) were age .2. 



SUMMARY 



1. Cruise and catch data of United States, 



Japanese, and Canadian research vessels in the 

 North Pacific Ocean for 1953 and 1955-67 and 

 the scientific literature were analyzed for in- 

 formation on distribution, age, and size of steel- 

 head trout in the ocean. Data are not available 

 from all nations in all years, but considerable 

 information was obtained. 



2. Catches were made with gill nets, long- 

 lines, and purse seines. U.S. catches were with 

 gill nets and longlines by the National Marine 

 Fisheries Service (NMFS) and with purse 

 seines and longlines by the Fisheries Research 

 Institute (FRI), University of Washington. 

 Japanese and Canadian vessels used gill nets 

 and longlines. The catch per set was chosen as 

 the comparative unit of effort because of the 

 great variation in types of gear used and varia- 

 tion in construction and in methods of fishing 

 gill nets. 



3. Catches by research vessels showed steel- 

 head trout to be distributed virtually throughout 

 the Gulf of Alaska and the North Pacific Ocean 

 north of about lat. 42°N to the Aleutian Islands 

 chain and west from the coast of North America 

 to about long. 152 °E. Steelhead trout rarely 

 were found north of the Aleutian Islands in the 

 southern Bering Sea and in the southeastern 

 Okhotsk Sea (catch reported by the Japanese). 

 None were reported in fishing sets in the Bristol 

 Bay area, central and northern Bering Sea, 

 central and western Okhotsk Sea, or the Sea of 

 Japan. 



4. The relative abundance of steelhead trout 

 could be indicated only in a general way. 

 Because the fishing gear often varied between 

 years and between areas and because catches 

 were relatively small, the catch per set was 

 chosen as the comparative unit of effort. Data 

 on the catch per set indicated that the abun- 

 dance of steelhead trout was greatest in the Gulf 

 of Alaska and eastern North Pacific Ocean, 

 decreased westward, and reached a low level 

 in the western North Pacific and western Aleu- 

 tian Islands area. Fishing primarily east of long. 

 180°, NMFS research vessels averaged 1.05 

 steelhead trout per gill net set. In the same 

 general area research vessels of NMFS, FRI, 

 and FRBC averaged 0.75, 0.81, and 1.00 steel- 

 head trout per longline set, respectively. Fish- 

 ing primarily west of long. 175 °W, the Japanese 



804 



