618 



Fishery Bulletin 94(4), 1996 



20 



30 



— 23.13 



— 9.42 



— 6.56 



15 



2C 



30 



J.- -.«. : -.-J 



— 6.56 



— 4.36 





Figure 2 



Autoradiography of chum salmon DNA restricted with Haelll and hybridized with the probe pSsa-A33 

 (A) or pSsa-A34 (B). In panel A, lanes 1, 11, 20, and 30 represent size-standard fish; lanes 2 and 29 

 represent standard fish; lanes 3-8, 16-19, and 21-22 represent Atnarko fish; and 9-10, 12-15, and 

 23-28 represent Chilliwack fish. In panel B, the lanes are similar; Chilliwack chum salmon DNA is 

 seen in lanes 3-8, 16-19, and 21-22, and Nitinat chum salmon DNA in lanes 9-10, 12-15, and 24-29. 



or greater for east coast of Vancouver Island (ECVI), 

 mainland British Columbia, or Fraser River stocks 

 (Table 1). However, within a region, marked differ- 

 ences in allelic frequencies could be observed among 

 stocks. For example, frequency of the allele greater 

 than 16.0 kbp ranged between 0.16 and 0.28 for six 

 Fraser River stocks, and frequency of the 11.0-13.0 

 kbp allele ranged between 0.13 and 0.39 for seven 

 ECVI stocks. This variation in allele frequencies among 

 stocks within regions may allow discrimination among 

 stocks within the region but it increases the complex- 

 ity of discriminating among stocks between regions. 



Genotypic frequencies at the Ssa -A33 locus were 

 in Hardy-Weinberg equilibrium in all 42 stocks 

 sampled. On a regional basis, heterozygosity ranged 

 from 54 to 72% for the stocks sampled, with Japa- 

 nese stocks significantly more heterozygous than the 

 pooled aggregate of North American stocks (G=6.03, 

 df=l,P<0.05)(Table 1). 



Geographic variation in Ssa-A34 allele 

 frequencies 



Allele size varied from 2.6 to 8.5 kbp (Fig. 2), with 

 major alleles at 3.7-3.9 kbp (bin 8), 3.9-4.1 kbp (bin 



9), and 4.4-4.7 kbp (bin 11) (Fig. 1; Table 2). As with 

 the Ssa-A33 locus, differences in allele frequencies 

 were observed among Japanese, Russian, and North 

 American stocks. Of the Russian stocks surveyed, all 

 had a relatively high frequency (mean 0.60) of the 

 4.4-4.7 kbp allele, significantly different from Japa- 

 nese stocks (mean 0.21)(x 2 =89.6, df=l, P<0.01)(Table 

 2). Mean frequency of the 3.7-3.9 kbp allele was 0.08 

 in Japanese stocks, 0.22-0.25 in Russian and Yukon 

 River stocks, and 0.40-0.52 in southeast Alaska and 

 British Columbia stocks. Similar patterns of the ge- 

 netic distinctiveness of the major stock groups were 

 observed at both the Ssa-A33 and Ssa-A34 loci. 



In British Columbia, regional differences in allele 

 frequencies were fairly minor in comparison with the 

 variation among stocks within regions (Table 2). For 

 example, in the six Fraser River stocks, frequencies 

 of the 4.4-4.7 kbp allele ranged from 0.13 to 0.38 

 (mean 0.27), in the seven ECVI stocks from 0.18 to 

 0.41 (mean 0.24), and in the four mainland stocks 

 from 0. 19 to 0.35 (mean 0.28). The variation in allele 

 frequencies among stocks within regions may be used 

 effectively for localized stock discrimination, but as 

 with the Ssct-A33 locus, makes discrimination among 

 regional groups of stocks more difficult. 



