GENETIC-RELATIONSHIPS AMONG CHUM SALMON POPULATIONS IN SOUTHEAST ALASKA AND NORTHERN BRITISH-COLUMBIA

Allozymes from 46 loci were analyzed from chum salmon (Oncorhynchus ke ta) collected at 61 locations in southeast Alaska and northern British Columbia. Of the 42 variable loci, 21 had a common allele frequency < 0.95. We observed significant heterogeneity within and among six regio nal groups: central southeast Alaska, Prince of Wales island area, sou thern southeast Alaska - northern British Columbia, north-central Brit ish Columbia, and two groups in the Queen Charlotte islands. Genetic v ariation among regions was significantly greater than within regions. The three island groups were distinct from each other and from the mai nland populations. Allele frequencies were stable over time in 14 of 1 5 locations sampled for more than 1 yr. The geographic basis for heter ogeneity among regions is confounded in part by spawning-time differen ces. The Prince of Wales and Queen Charlotte populations spawn in the fall; the mainland populations spawn mainly in the summer, although so me overlap exists. Overall, most genetic diversity (97%) occurred with in sampling locations; the remaining diversity was distributed almost equally within and among regions. Our genetic data may provide fishery managers a means to estimate stock composition in the mixed-stock fis heries near this boundary between the United States and Canada.