MOSHER: SCALE FEATURES OF SOCKEYE SALMON 



60°N 



60°N 



50° 



Figure 2. — Approximate 



1. Okhota River 



2. Kukhtuy River 



3. Okhotsk Sea 



4. Bolshaya River 



5. Ozernaya River 



6. Paratunka River 

 (Dalnee and 



Blizhnee Lakes) 



7. Kamchatka River 



8. Apuka River 



9. Anadyr River 



10. Attu Island 



11. Adak Island 



12. Unalaska Island 



and 37 of Mosher, 1963) are shown for the var- 

 ious areas as frequency tabulations in Tables 4 

 and 5 for the age 1. fish; in Tables 6 and 7 for 

 the age 2. fish; and in Table 8 for the age 3. fish. 

 Inspection of Tables 4 and 6 shows that the 

 mean number of circuli in the freshwater zone 

 varies among some geographical areas, but that 

 in the first ocean zone (Tables 5 and 7) there is 

 a cline in number of circuli from least in the Adak 

 Island fish to most in the central British Colum- 

 bia areas of Rivers and Smith Inlets and the 

 Nimpkish River. A decrease in the mean num- 

 ber of circuli among stocks from central British 

 Columbia southward to the Columbia River is 

 also found. The Asian fish and those north of 

 Bristol Bay have slightly more circuli, on the av- 

 erage, than those of Adak Island and Bristol Bay. 



The scales from sockeye taken from certain 

 geographic areas have similar frequency distri- 

 butions of circuli in the freshwater or first ocean 

 zone. These similarities are the basis for di- 

 viding the coast of North America into certain 

 broad areas. When I discuss the various geo- 

 graphic areas, reference will be made to the 

 appropriate frequency table. 



PREPARATION OF PLATES 



The scale plates for the report were made as 

 follows: (1) The scale images produced by a 

 scale projector like the one I described (Mosher, 

 1950) , at 82 x magnification, were photographed 

 with a 35-mm single lens reflex camera on me- 

 dium speed, fine grained film and processed to 

 accentuate the contrast by minimum exposure 



145 



