MOSHER: SCALE FEATURES OF SOCKEYE SALMON 



marks labelled "1" on p. 260 of Mosher, 1968) ; 

 (2) a relatively small number of circuli in the 

 ocean zones; and (3) a wider spacing of the 

 circuli usually near the freshwater zone. 



In the other geographical areas, except Adak 

 Island, there are more circuli, on the average, 

 in the first ocean zone on the scales, and the 

 winter zone may be diffuse (see winter marks 

 labelled "3" on p. 260 of Mosher, 1968). These 

 features result in a more even spacing of ocean 

 circuli and a smaller average width per circulus 

 producing a less "open" appearance. The ef- 

 fect of this characteristic is reflected in the size 

 of the widest five adjacent circuli in the first 

 ocean zone in the frequency tabulations shown 

 in Table 10. This table shows that Bristol Bay 

 scales, on the average, have five adjacent cir- 

 culi that are substantially wider than on scales 

 from fish of other geographical areas. This 

 feature is found on scales of Bristol Bay salmon 

 of all freshwater ages. Krogius and Krokhin 

 (1956) also have noted variation in spacing of 

 circuli. 



Aleutian Islands to Cook Inlet (Plate 5; 

 Tables 4 and 5) 



The area from Chignik to Cook Inlet is an area 

 of high production of Alaskan sockeye salmon, 

 usually second to that of Bristol Bay. To provide 

 a comparison with other areas, the commercial 

 catch in 1966 of sockeye salmon in the subsec- 

 tions of this geographic area are shown below 

 (International North Pacific Fisheries Commis- 

 sion, 1966) : 



Area 



Thousands of fish 



Commercial fishing operations in the Aleutian 

 Islands and along the south side of the Alaska 

 Peninsula take both transient fish migrating to 

 Bristol Bay and local stocks (Atkinson, 1955). 

 My samples from the Aleutian Islands, obtained 

 for INPFC purposes, are of local stocks. 



Table 10. — Frequency tabulations of the width of the widest five adjacent circuli in the first ocean zone of age 1. 

 sockeye salmon from representative areas.^ (Asterisks indicate modes.) 



Width" 



Asia* 



Bristol 

 Bay 



Chignik 



Cook 

 Inlet 



Fish 

 Creek 



Ketch- 

 ikan 



Skeena 

 River 



Rivers 

 Inlet 



Fraser 

 River 



Columbia 

 River 



No. in 

 sample 



54 



281 



80 



82 



50 



88 



85 



87 



82 



1 All samples from 1963 except Ketchikan, 1964. 



" Millimeters of projected image, magnification 82X. i- r-i c l j ,j 



3 Asian samples from an area near Southeastern Kamchatka coast where Asian fish are present almost exclusively (Margolis, Cleaver, tukuda, and 

 Godfrey, 1966). Data smoothed according to Henry (1961). 



171 



