SCALE FEATURES OF SOCKEYE SALMON FROM ASIAN AND 

 NORTH AMERICAN COASTAL REGIONS 



Kenneth H. Mosher' 



ABSTRACT 



Photographic plates of sections of sockeye salmon scales, with descriptions, and frequency tables of the 

 number of circuli in the freshwater and first ocean zones illustrate the variations in scale features of 

 fish over the range of the species in coastal regions of Asia and North America. Suggestions are also 

 given for using these data to determine the geographical origin of sockeye salmon taken in offshore areas 

 of the North Pacific Ocean and adjacent waters. 



Sockeye salmon {Oyicorhynchus nerka) are val- 

 uable food fish of the Bering Sea and the north- 

 ern part of the North Pacific Ocean. They 

 spawn in coastal streams of Asia and North 

 America but spend a portion of their lives feed- 

 ing in oceanic areas. Upon the onset of sexual 

 maturity, they migrate from the ocean, enter 

 their natal streams, spawn, and then die. Be- 

 cause sockeye return to natal streams to spawn, 

 the species is divided into hundreds of individual 

 populations (each from its own geographical 

 area), which are self-reproducing units or 

 "stocks." 



A major goal in fisheries research and man- 

 agement of the sockeye salmon resource is to 

 obtain enough spawning fish within each stream 

 to provide the maximum catch to the fishery and 

 to insure the perpetuation of each stock. This 

 goal is difficult to attain in fishing areas where 

 management agencies are uncertain of the geo- 

 graphic area of origin of the stocks of fish that 

 are being caught. Consequently, methods for de- 

 termining the area of origin of sockeye salmon 

 taken beyond their natal streams are needed. 



A number of methods have been used to de- 

 termine the area of origin of sockeye salmon 

 taken in offshore and coastal areas. These in- 

 clude morphological studies (Fukuhara et al, 

 1962; Landrum and Dark, 1968), parasitologi- 

 cal studies (Margolis, 1963), serological studies 



' National Marine Fisheries Service, Northwest Fish- 

 eries Center, 2725 Montlake Boulevard East. Seattle, WA 

 98102. 



(Ridgway, Klontz, and Matsumoto, 1962), tag- 

 ging studies (Hartt, 1962, 1966; Kondo et al., 

 1965), and scale studies (Krogius, 1958; Kubo, 

 1958'; Kubo and Kosaka, 1959'; Henry, 1961; 

 Mosher, Anas, and Liscom, 1961; and Mosher, 

 1963, 1968). Scale studies have become one of 

 the most popular and successful methods; scale 

 features, for example, are routinely used by in- 

 vestigators of the International Pacific Salmon 

 Fisheries Commission as one element in a tech- 

 nique to determine the natal streams of sockeye 

 taken near the mouth of the Fraser River and 

 are also routinely used by investigators of the 

 National Marine Fisheries Service (NMFS, 

 formerly the Bureau of Commercial Fisheries) 

 to determine continent of origin of sockeye salm- 

 on taken in the Bering Sea and the central North 

 Pacific Ocean. 



No detailed information, however, has been 

 published on the variations in scale features 

 among fish from diff'erent spawning regions 

 along the Asian and North American coasts. 

 Krogius (1958) specifically mentioned the need 

 for an atlas illustrating scales from difl["erent 



Manuscript accepted September 1971. 

 FISHERY BULLETIN: VOL. 70, NO. I, 



1972. 



" Kubo, T. 1958. Study of sockeye salmon stocks by 

 means of the growth pattern of scales (preliminary re- 

 port). Fac. Fish., Hokkaido Univ. (Hakodate). Part I 

 - 15 p. of Japanese text; Part II - 2 pi., 16 fig. in English. 

 (Transl. of Part I, Int. North Pac. Fish. Comm. Doc. 

 206), 9 p. (Processed.) 



^ Kubo, T., and J. Kosaka. 1959. A study of 5,^ age 

 group red salmon stocks by scale growth formula [in 

 Japanese with English abst., headings, tables, and fig. 

 legends.] Suisan cho (Fisheries Agency of Japan), (Int. 

 North Pac. Fish. Comm. Doc. 826), 27 p. (Processed.) 



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