

Figure 9. — Scale of a chlnook salmon with a magnified 

 portion of the center, age 1.1. 



Figure 10. — Scale of a chlnook salmon, age 2.2. 



of circuli which are complete below the focus 

 of the scale: the sockeye and chum salmon, 

 six or less; the chinook salmon, more than six 

 (fig. 11). 





Figure 11. — Scale of an ocean-run chinook salmon, with a 

 magnified portion of the center, age 0.1. 



Masu Salmon (figs. 12 and 13) ^ 



This species occurs only on the Asian side 

 of the Pacific Ocean, and research fishing by 

 United States and Canadian scientists has not 

 yet included any masu salmon. 



Life history and offshore distribution data on 

 the masu salmon were summarized by Tanaka 

 (1965). He reported that masu salmon resemble 

 the coho salmon in many morphological and 

 ecological aspects. 



My examination of a series of masu salmon 

 scales showed that they resemble scales from 

 coho salmon in several features, but are dif- 

 ferent in some others. 



The features that are similar to those of the 

 coho salmon are: 



1. Age. Tanaka reported that in 

 Hokkaido, Japan, over 90 percent of the 

 masu salmon mature at age 32 (1.1), the 

 others at age 4j (2.1). In Kamchatka, 

 some fish stay over another year at sea 

 to mature at age 42 (1.2) or 63 (2.2), de- 

 pending on their fresh-water history. 



^Slnce Koo (1962b) and Bllton, Jenkinson, and Shepard 

 (1964) did not include the masu salmon or steelhead trout 

 in their papers, 1 am including a number of examples of 

 scales of these two species to illustrate some of the 

 variations that may be encountered In the study of these 

 fish. 



