Development of molecular markers for genetic stock identification of chum salmon

We are conducting a collaborative study to develop molecular markers and baseline information for chum salmon (Oncorhynchus keta) to address stock identification problems and other issues. To date, more than 2,000 individuals representing 46 populations from Japan/Korea, Russia and North America (Alaska, British Columbia and Washington) have been evaluated with mitochondrial (mt) DNA sequence variation and/or at five microsatellite (ms) DNA loci. Analysis of mtDNA disclosed a greater genetic variation in the populations of Japan than those of Russia and North America and a distinct genetic differentiation among the three regional groups of populations, in addition to more than 20 region-specific haplotypes. Similar genetic variation was also found using msDNA, although allelic variation was different among the examined loci. Besides estimation of the genetic differentiation and stock origin of chum salmon, our DNA markers, particularly mtDNA analysis, may provide a useful means for understanding the historical origin and the formation of population structure in this species.