Table 1. --Variation in number of vertebrae in Pacific herring 



Rounsefell found what he considered to be 

 significant differences between samples from 

 the same area . The variation was largely due to 

 differences between year classes. The 1921 

 year class in McClure Bay (Prince William Sound 

 area) differed from the 1923 year class by 0.67 

 vertebra. This was the extreme variation found. 

 Samples composed of several year classes did 

 not differ as much; the greatest variation found 

 between such samples was 0.26 vertebra (Larch 

 Bay, S.E. Alaska). When considering the sig- 

 nificance of differences between two localities, 

 it is essential to take into account the variation 

 found between samples in the same locality. 



On the basis of vertebral counts, Rounsefell 

 postulated the distinctness of the populations in 



the following areas studied: California; southern 

 British Columbia; three areas in S E . Alaska 

 (Craig, Chatham Strait and Stephens Passage); 

 three areas in central Alaska (Cook Inlet- 

 Shuyak Strait, Prince William Sound, Shearwater 

 Bay - Old Harbor); and four areas in western 

 Alaska (Chignik, Shumagin Islands, Unalaska 

 and Golovin Bay) . 



Dorsal -ray counts. --The Pacific herring 

 has from 15 to 21 dorsal rays with 17 to 20 being 

 the usual number. Mean number of dorsal rays 

 in fish from 9 localities between Puget Sound and 

 Unalaska ranged from 18 .70 to 19.05 (1 small 

 sample had a mean of 19.36) . The number of 

 dorsal rays does not exhibit any general change 

 with latitude, as do vertebrae, but appears to 



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