Michael Wetklo

Estimation of Stock Composition and Individual Identification of Chinook Salmon across the Pacific Rim by Use of Microsatellite Variation

Abstract Variation at 13 microsatellite loci was surveyed for over 52,000 Chinook salmon Oncorhynchus tshawytscha sampled from 325 localities ranging from Russia to California; the variation was applied to estimate stock composition in mixed-stock fishery samples. A rapid increase in the accuracy of estimated stock composition in simulated mixtures with respect to population sample size was observed for sample sizes of up to about 75 individuals, at which point a 90% accuracy of assignment to population was achieved. The number of alleles observed at a locus was related to the power of the locus in providing accurate estimates of the stock composition of single-population mixtures. In analysis of single-population mixtures where the Pacific Rim baseline was used for estimation of stock identification, 75% accuracy for the average population was achieved by employing approximately 55 alleles in the analysis. Increasing the accuracy of the estimated stock composition to 90% for the average population requir...

The Application of Rapid Microsatellite-Based Stock Identification to Management of a Chinook Salmon Troll Fishery off the Queen Charlotte Islands, British Columbia

Abstract Since 1995, the Northern British Columbia (NBC) troll fishery has been managed to reduce exploitation on stocks of Chinook salmon Oncorhynchus tshawytscha from the West Coast of Vancouver Island (WCVI). Before 2002, management actions in the NBC troll fishery were generally large-scale quota reductions and area closures that resulted in substantially reduced catches of Chinook salmon relative to the existing quota. Since 2002, in-season microsatellite-based stock identification has been used to address WCVI Chinook salmon management in the NBC troll fishery. The change in management strategy has resulted in increased quota utilization and increased catches of approximately 390,000 fish during 2002–2005. The increased catch in the fishery was concurrent with average fishing mortality on the main WCVI hatchery indicator stock declining from an average 3.3% during the era of reduced catches (1995–2001) to 2.3% since 2002, when in-season, microsatellite-based stock identification was applied to guide...

Coho Salmon Population Structure in North America Determined from Microsatellites

Abstract Population structure of coho salmon Oncorhynchus kisutch from Russia to California was examined with a survey of microsatellite variation to describe the distribution of genetic variation. Variation at 17 microsatellite loci was surveyed for approximately 50,000 coho salmon sampled from 318 localities. The genetic differentiation index (F ST) over all populations and loci was 0.058, with individual locus F ST values ranging from 0.027 to 0.143. The least genetically diverse coho salmon were observed from Russia, the Porcupine River in the Yukon River drainage, and the middle Fraser and Thompson rivers in southern British Columbia. Coho salmon from Vancouver Island, British Columbia; Puget Sound, Hood Canal, and Juan de Fuca Strait, northern Washington; and Oregon displayed the greatest number of alleles compared with coho salmon in other regions. Differentiation in coho salmon allele frequencies among regions and among populations within regions was approximately seven times greater than that of ...

Microsatellite Stock Identification of Chum Salmon on a Pacific Rim Basis

Abstract The variation at 14 microsatellite loci was analyzed for more than 53,000 chum salmon Oncorhynchus keta from 381 locations ranging from Korea to Washington State and used to estimate the stock composition of mixed-stock fishery samples. High resolution of the samples was possible, the number of reporting groups being distributed as follows: Korea = 1, Japan = 7, Russia = 8, Alaska = 15, Canadian Yukon River = 5, British Columbia = 16, and Washington State = 5. The number of alleles observed at a locus was related to the power of the locus in providing accurate estimates of the stock composition of single population mixtures. Approximately 800 alleles were observed across the 14 microsatellites, providing the basis for high-resolution stock identification. Analysis of known-origin samples indicated that accurate regional estimates of stock composition were obtained. The estimated stock compositions of mixed-fishery samples from coastal Japan, the Sea of Okhotsk, the western Pacific Ocean, the Gulf...

Population structure and stock identification of chum salmon Oncorhynchus keta from Japan determined by microsatellite DNA variation

Variation at 14 microsatellite loci was surveyed in 26 chum salmon Oncorhynchus keta populations from Japan, one population from West Kamchatka and three populations from North America to determine population structure. Microsatellites were then applied to estimate stock composition of chum salmon in mixed-stock fisheries. The genetic differentiation index (Fst) over all populations and loci was 0.031, with individual locus values ranging from 0.010 to 0.081. Seven regional populations were observed in Japanese chum salmon, with late-run populations from the Pacific Coast of Honshu the most distinct. Japanese populations displayed greater genetic diversity than did those in North America. Transplantation history in some Japanese river populations influenced their present genetic characteristics. Analysis of simulated mixtures from fishery sampling suggested that accurate and precise regional estimates of stock composition should be produced when the microsatellites were used to estimate stock compositions. Stock compositions for a 2005 sample of maturing, migrating chum salmon off the north-west coast of Hokkaido near the border of the Sea of Japan and the Sea of Okhotsk indicated that this region may be a migration corridor for Hokkaido populations from the Sea of Japan coast. Microsatellites have the ability to provide fine-scale resolution of stock composition in Japanese coastal fisheries.

Population genetic structure and demographic history of Pacific blue sharks (Prionace glauca) inferred from mitochondrial DNA analysis

Cosmopolitan pelagic species often show shallow genetic divergence and weak, or no, genetic structure across a species’ range. However, there have been few such genetic studies for pelagic sharks. The pelagic blue shark (Prionace glauca) has a broad circumglobal distribution in tropical and temperate oceans. To investigate the population genetic structure and demographic history of this species, we analysed variation in the mitochondrial cytochrome b sequence for a total of 404 specimens collected from 10 locations across the Indo-Pacific region. The observed genetic diversities were comparable among sampling locations (h=0.77–0.87; π=0.17–0.23%). Spatial analysis of molecular variance (SAMOVA), pairwise ΦST and conventional FST estimates, and analysis of isolation with migration indicated weak or no genetic differentiation of this species across the Indo-Pacific region. The results of three phylogeographic analyses (i.e. mismatch distribution and parsimony haplotype network analyses and a neutrality test) suggested that the Pacific blue shark had historically experienced a sudden population expansion. These results, coupled with the biological properties of this species, imply that historical climate fluctuation has had only a minor effect on the genetic structuring of the blue shark.

Microsatellite Mixed-Stock Identification of Coho Salmon in British Columbia

Abstract Variation at 17 microsatellite loci was analyzed for about 50,000 coho salmon Oncorhynchus kisutch sampled from 274 locations ranging from Russia to California (but largely from British Columbia), and the variation was applied to estimate stock composition in mixed-stock fishery samples. High resolution of mixed-stock samples was possible; accurate estimates of stock composition were available for coho salmon originating from 39 regions (Russia, 1 region; Yukon River, 1; southeast Alaska, 1; British Columbia, 28; Washington, 5; Columbia River, 1; Oregon, 1; California, 1). The power of a locus in providing accurate estimates of stock composition of simulated single-population mixtures was related to the number of alleles observed at the locus. Approximately 800 alleles were observed across the 17 microsatellites. Analysis of known-origin samples indicated that accurate regional estimates of stock composition were obtained; estimates from 37 of 39 regions had accuracy greater than 90%. Estimated stock compositions of five mixed-fishery samples collected in British Columbia and the San Juan Islands (Washington) reflected the presence and timing of migration of the local populations. Microsatellites provided accurate estimates of stock composition from many locations in the British Columbia distribution of coho salmon.