FISHERY BULLETIN: VOL. 71, NO. 3 



exception failed to show a saltwater growth 

 pattern characteristic of steelhead trout (R. L. 

 Burgner.FisheriesResearch Institute, University 

 of Washington, Seattle, pers. comm.). 



The distribution of steelhead trout is not 

 known to include coastal streams of Asia. The 

 literature on Asian fishes does not list S. gaird- 

 neri as a native species. Some fish identified as 

 steelhead trout, however, have been taken close 

 to Asia. Steelhead trout were reported in the 

 catches of Japanese research vessels in the Ok- 

 hotsk Sea near the coast of southwest Kam- 

 chatka in 1962, 1964, and 1967 (Appendix 

 Figures 11, 12). The locality of the catches may, 

 therefore, represent an extension of the range of 

 steelhead trout of North American origin, or the 

 fish might possibly have been misidentified. The 

 latter appears most likely as the taxonomy of 

 the genus Salnto in Asia is unresolved. For 

 example, Behnke (1966) considered two species 

 of trout in the Far East, S. luykiss and S. peti- 

 !ihiiie)isis, to be a single species, S. nnjkiss, with 

 both anadromous and nonanadromous popula- 

 tions. Behnke further stated that the single 

 species is most clearly related to the rainbow 

 trout, S. gainhieri. In his opinion, "The only 

 apparent distinction between S. uiykiss and S. 

 gairdneri is the number of vertebrae." Berg 

 (1948) described S. mykiss and S. pe)ishi)ieiisis 

 as separate species, but he noted that S. mykiss 

 is related to S. pc)ishi}ie)isis as S. trutta is 

 related to S. salar. Taxonomic study of the Far 

 Eastern species is complicated by the rarity of 

 specimens. Shmidt (1950) emphasized the lack 

 of specimens of S. pe)ishiiieiisis and said, "... 

 all attempts to receive it from Kamchatka have 

 hitherto been of no avail." Behnke's (1966) 

 review also pointed out the lack of samples of 

 both S. mykiss and S. pe)ishine)isis. Thus, 

 although steelhead trout are not recorded in the 

 Far East, species taxonomically similar to the 

 steelhead trout have been described. 



Steelhead trout hatch in freshwater streams, 

 migrate to sea to grow and mature, and return 

 to their natal streams to spawn as adults after 

 usually spending one or more summers in the 

 ocean. The young steelhead trout may migrate 

 to sea soon after emerging from the gravel of 

 their home stream or delay migration for 

 several years. The period of residence in salt 



water is similarly indefinite. Some return to 

 fresh water aftei- a short stay and others 

 remain in salt water for several years. Scale 

 studies of adult steelhead trout indicate few 

 fish survive that migrate to sea in the year of 

 emergence. Residence in salt water is an essen- 

 tial part of their life history. Anadromy among 

 S. gaird)ieri is optional, however (Rounsefell, 

 1958). The progeny of steelhead trout are not 

 certain to follow the anadromous habits of their 

 parents; instead some may spend their entire 

 lives in fresh water. 



The anadromy of steelhead trout is similar 

 in some respects to that of Pacific salmon, 

 OncorhyncJius spp. Both reside temporarily in 

 fresh water after hatching, migrate to sea, and 

 return to their home streams on reaching 

 maturity. Steelhead trout do not always die 

 after spawning, as do Pacific salmon, but may 

 survive to repeat the migration, maturation, 

 and spawning process in the manner of Atlan- 

 tic salmon, S. salar (Bureau of Sport Fisheries 

 and Wildlife, 1962). 



Because of incomplete catch and escape- 

 ment statistics, agencies that manage steelhead 

 trout fisheries rely primarily on annual indices 

 of abundance derived from commerical and 

 sport landings, hatchery returns, counts at fish- 

 passage facilities, and spawning ground surveys 

 (Larson and Ward, 1955 Washington Game 

 Department, 1968). Individually or collectively, 

 the indices generally do not accurately estimate 

 the total population size. Therefore, no attempt 

 was made in this study to relate annual fluctua- 

 tions of the apparent relative abundance of 

 steelhead trout in offshore waters to inshore 

 "runs." 



The commercial landings of steelhead trout 

 have declined substantially in the United States 

 in recent years. The annual landing in the 

 Pacific Coast states averaged 247,000 kg 

 (543,000 lb.) in 1964-67 compared to 485,000 kg 

 (1,068,000 lb.) during 1960-63 (Power, 1962, 

 1963; Power and Lyles, 1964; Lyles, 1965, 1966, 

 1967, 1968, 1969). By state, about 71% were 

 landed in Oregon, 25% in Washington, and 4% 

 in Alaska. The decline may be attributed in 

 part to changes in fishing regulations that limit 

 the commercial catch and increase the avail- 

 ability of the fish to sport fishermen. The steel- 



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