We used the geographic distributions of biochemical genetic variants in sockeye salmon (Oncorhynchus nerka) to describe features of its population structure and to identify stocks in commercial catches from the central fishing district of Cook Inlet, Alaska. Allelic frequencies for 6 polymorphic loci were determined for samples of 13 spawning areas using starch gel electrophoresis and were used as the basis of stock classification. The level of genetic variation, estimated by average heterozygosity, was 4.6%. Likelihood ratio tests for heterogeneity among allelic frequencies indicated a significant degree of heterogeneity among spawning areas within the Susitna and Kenai rivers, but not among the spawning areas within the Kasilof River. These tests also indicated that for the Kasilof River, where multi-year samples were taken, allelic frequencies were not significantly different for two consecutive years. Cluster analysis of genetic similarities between samples indicated that the samples from the Kasilof River were distinct from samples of the Kenai and Susitna rivers, but that Kenai and Susitna River samples were not distinct from one another. Maximum likelihood estimates of the stock composition of samples collected from the set- and drift-gillnet fisheries were made on a weekly basis during the commercial fishing season. These estimates indicated that Susitna River fish predominated in the 1976 run into Cook Inlet.Key words: sockeye salmon, Oncorhynchus nerka; stock identification, biochemical genetic variation, population genetics, Cook Inlet, electrophoresis
We used protein electrophoresis to examine genetic population structure and origin of life history types of chinook salmon Oncorhynchus tshawytscha in British Columbia, Canada. Among 31 allozyme loci resolved in 91 samples from 63 populations of chinook salmon in rivers and hatcheries throughout British Columbia, population heterozygosities averaged 0.084 (range 0.048–0.108) and were typical of values for populations in other regions. A hierarchical gene diversity analysis indicated that 91.3% of the total allele‐frequency diversity was attributable to within‐population variability; the remaining 8.7% was attributable to geographic variability among populations, which was partitioned into among‐river (3.3%), among‐area (3.5%), and among‐region (1.9%) components. Two major groups of populations appeared in the principal components analysis and in cluster analysis of genetic distances. A coastal group included populations in four subgroups: Central coast, Georgia Strait, lower Fraser River, and west Vancouver Island. An inland group included six subgroups: Nass River, Skeena River, north Thompson River, upper and mid‐Fraser River, south Thompson River, and lower Thompson River. The geographic extents of the inland and coastal groups largely coincided with the geographic distributions of stream‐ and ocean‐type juvenile forms and may reflect postglacial colonization by two ancestral lineages that survived in Pleistocene refugia. The presence of genetically undifferentiated stream‐type fish in coastal streams populated by ocean‐type fish may reflect either postglacial life history differentiation from ancestral ocean‐type fish or life history flexibility of ocean‐type fish.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.