MOSHER: SCALE FEATURES OF SOCKEYE SALMON 



quire different considerations for study. The 

 following discussion is divided into two parts 

 for purposes of racial identification of the fish: 



1. The area westward of long 175° W in the 

 North Pacific Ocean and Bering Sea. 



2. The eastern North Pacific Ocean and Gulf 

 of Alaska. 



WESTERN AND CENTRAL NORTH 

 PACIFIC AND BERING SEA 



Studies of the distribution of sockeye salmon 

 stocks in central North Pacific and Bering Sea 

 for the INPFC, including the morphological, 

 parasitological, and tagging reports noted in the 

 introduction, as well as the scale studies of 

 Mosher (1963) and Mason (1966, 1967a, 1967b) 

 have shown intermingling of stocks primarily 

 from Asia and Bristol Bay over most of the off- 

 shore area westward of long 175° W to between 

 160° and 170° E, depending on the latitude (see 

 Figure 74 of Margolis et al., 1966). 



When examining scales of fish from this area, 

 occasionally a scale with a very large freshwater 

 zone may be seen. These scales usually stand out 

 distinctly from others and are most likely from 

 Lake Dalnee fish (Plates 3, 10, 15, and 17). A 

 few scales, however, may be seen with unusually 

 small freshwater zones. These scales are most 

 likely from fish from Lake Blizhnee (Plates 3, 

 10, 15, and 17). 



Aside from these scales with unusually large 

 or small freshwater zones, nearly all of the scales 

 are of two types: (1) Bristol Bay type scales 

 (Plates 4, 11, 16, and 17) — well-marked scales 

 with regular circuli in all growth zones and a 

 moderately large freshwater zone, usually with 

 less than 23 circuli in the first ocean zone. The 

 widest spacing of circuli in the first ocean zone 

 (and often the other ocean zones as well) is 

 usually near the freshwater zone. The ocean 

 portion of these scales has an open appearance. 

 (2) Asian type scales (Plates 3, 10, 15, and 17) 

 —relatively small freshwater zones with many 

 broken or irregular circuli. The first ocean zone 

 usually has 23 to 26 circuli which are widely 

 spaced over the whole summer growth portion 

 but lack the open appearance of the Bristol Bay 



scales. The ocean zone of these fish often has 

 three and sometimes four winter marks. 



EASTERN NORTH PACIFIC OCEAN 

 AND GULF OF ALASKA 



When we examine scales of fish taken east- 

 ward of long 175° W and in the Gulf of Alaska, 

 many types may be encountered. At the present 

 state of knowledge, I believe that determination 

 of origin is extremely difficult or impossible if 

 separation by each individual stream or river 

 within the area is required. If, however, deter- 

 mination by general locality of origin and certain 

 areas is the immediate goal, age and scale char- 

 acteristics can be used to classify many, if not 

 most, of the fish. 



No sockeye salmon tagged in the Gulf of 

 Alaska has ever been returned from Asian coast- 

 al streams.'" Numerous sockeye tagged in other 

 areas and other species tagged in the Gulf of 

 Alaska have been returned from Asian coastal 

 rivers. Considering that many thousand sock- 

 eye salmon have been tagged in the Gulf of 

 Alaska, at least a few should have been recap- 

 tured from Asian waters if any Asian fish were 

 present there during the time of tagging. 



Thus, the Asian stocks need not be considered 

 when dealing with fish taken in the Gulf area. 

 Some of the scales of fish taken from the Alaska 

 Peninsula eastward to southeastern Alaska re- 

 semble Asian fish in some characters at least. 

 This similarity to Asian fish in scale characters 

 has been noted by Oseko (1961)," and in morpho- 

 logical characters, by Fukuhara et al. (1962). 

 Consequently any scales encountered in the Gulf 

 of Alaska samples that resemble those from 



" One fish tagged at 48°29' N, 159°10' W in the area 

 south of the Gulf of Alaska in 1961 was recovered the 

 same year off the Kamchatka coast at 50°47' N, 162°29' E. 

 Kondo et al. (1965) concluded that it was not possible 

 to draw any definite conclusions from the recovery. 

 Margolis et al. (1966), however, considered it a Kam- 

 chatka sockeye salmon. 



" Oseko, M. 1961. Certain characteristics of the 

 growth pattern of scales as a means of discriminating 

 between sockeye salmon from various streams of Alaska 

 and the Kamchatka Peninsula. [In Japanese.] Hokkaido 

 Reg. Fish. Res. Lab. (INPFC Doc. 479). 38 p. of Jap- 

 anese text; 5 p. of preliminary English translation. 

 (Processed.) 



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