Genetic Assessment of Inconnu (Stenodus leucichthys) from the Selawik and Kobuk Rivers, Alaska, using PCR and RFLP Analyses. Alaska Fisheries Technical Report Number 48, September 1998

摘要

Population structure of inconnu in the Kobuk and Selawik rivers in western Alaska was assessed using genetic methods. Collections from each of the rivers were performed in 1993 and 1994 in conjunction with an inconnu tagging study. Nonlethal sampling methods were used to collect samples of boney fin and scales (with epithelium attached) for DNA extraction. The polymerase chain reaction (PCR) was used to amplify three segments of the mitochondrial DNA (mtDNA) and one segment of the nuclear DNA (nucDNA). Restriction site analysis was used to assess genetic variation among individual fish for the cytochrome-B segment of the mtDNA and the growth hormone-1 segment of the nucDNA. Frequencies of mtDNA genotypes were significantly different between the Kobuk and Selawik collections. A total of four mtDNA genotypes were observed; all four occurred in the Selawik collections and two were in the Kobuk collections. The two mtDNA genotypes that were unique to the Selawik collections occurred at 8% each. Three nucDNA genotypes composed of two alleles occurred in both the Kobuk and Selawik collections at significantly different frequencies. Both the mtDNA and nucDNA revealed similar stock relationships and indicated that the Kobuk and Selawik rivers each support different stocks of inconnu that do not routinely interbreed. Further support for different stocks came from a multiyear tagging study showing that fish tagged in one river were not recaptured in the other river. Inconnu of the region support sport, commercial, and subsistence fisheries and have significant cultural importance. Our results can be used to address concerns about the overharvest of the smaller Selawik stock in mixed stock winter fisheries and to help formulate management plans to achieve harvest and conservation goals.