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Beacham, Terry D.; Wallace, Colin G.; MacConnachie, Cathy; Jonsen, Kim; McIntosh, Brenda; Candy, John R.; Devlin, Robert H.; Withler, Ruth E.; Wallace, Colin 2018-06-12 Parentage-based tagging (PBT) and genetic stock identification (GSI) were used to identify individual coho salmon (Oncorhynchus kisutch) to specific populations and brood years. In total, 20 242 individuals from 117 populations were genotyped at 304 single nucleotide polymorphisms (SNPs) via direct sequencing of amplicons. Coho salmon from 15 populations were assigned via parentage analysis that required the genotypes of both parents. The overall accuracy of assignment for 1939 coho salmon to the correct population was 100%, and to correct brood year within population was also 100%. Inclusion of individuals requiring only a single parental genotype for identification resulted in assignments of 2101 individuals, with an accuracy of 99.95% (2000–2001) to population and 100.0% to age. With 23 regions defined by the coded-wire tag (CWT) program, and individuals displaying an assignment probability <0.85 excluded from the analysis, mean regional assignment accuracy of individuals via GSI was 98.4% over all 23 regions. A PBT–GSI or PBT system of identification will provide an alternate method of identification in the assessment and management of Canadian-origin coho salmon relative to the existing CWT program.
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Beacham, Terry D.; Wallace, Colin; Jonsen, Kim; McIntosh, Brenda; Candy, John R.; Willis, David; Lynch, Cheryl; Moore, Jean-Sébastien; Bernatchez, Louis; Withler, Ruth E. 2018-09-07 Wild Pacific salmon, including Coho salmon Onchorynchus kisutch, have been supplemented with hatchery propagation for over 50 years in support of increased ocean harvest and conservation of threatened populations. In Canada, the Wild Salmon Policy for Pacific salmon was established with the goal of maintaining and restoring healthy and diverse Pacific salmon populations, making conservation of wild salmon and their habitats the highest priority for resource management decision-making. A new approach to the assessment and management of wild coho salmon, and the associated hatchery production and fishery management is needed. Implementation of parentage-based tagging (PBT) may overcome problems associated with coded-wire tag-based (CWT) assessment and management of coho salmon fisheries, providing at a minimum information equivalent to that derived from the CWT program. PBT and genetic stock identification (GSI) were used to identify coho salmon sampled in fisheries (8,006 individuals) and escapements (1,692 individuals) in British Columbia to specific conservation units (CU), populations, and broodyears. Individuals were genotyped at 304 single nucleotide polymorphisms (SNPs) via direct sequencing of amplicons. Very high accuracy of assignment to population (100%) via PBT for 543 jack (age 2) assigned to correct age and collection location and 265 coded-wire tag (CWT, age 3) coho salmon assigned to correct age and release location was observed, with a 40,774–individual, 267–population baseline available for assignment. Coho salmon from un-CWTed enhanced populations contributed 65% of the catch in southern recreational fisheries in 2017. Application of a PBT-GSI system of identification to individuals in 2017 fisheries and escapements provided high-resolution estimates of stock composition, catch, and exploitation rate by CU or population, providing an alternate and more effective method in the assessment and management of Canadian-origin coho salmon relative to CWTs, and an opportunity for a genetic-based system to replace the current CWT system for coho salmon assessment.
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McClelland, Erin K.; Ming, Tobi J.; Tabata, Amy; Kaukinen, Karia H.; Beacham, Terry D.; Withler, Ruth E.; Miller, Kristina M. 2013-06-19 The major histocompatibility complex (MHC), an important component of the vertebrate immune system, provides an important suite of genes to examine the role of genetic diversity at non-neutral loci for population persistence. We contrasted patterns of diversity at the two classical MHC loci in sockeye salmon (Oncorhynchus nerka), MHC class I (UBA) and MHC class II (DAB), and neutral microsatellite loci across 70 populations spanning the species range from Washington State to Japan. There was no correlation in allelic richness or heterozygosity between MHC loci or between MHC loci and microsatellites. The two unlinked MHC loci may be responding to different selective pressures; the distribution of FST values for the two loci was uncorrelated, and evidence for both balancing and directional selection on alleles and lineages of DAB and UBA was observed in populations throughout the species range but rarely on both loci within a population. These results suggest that fluctuating selection has resulted in the divergence of MHC loci in contemporary populations.
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Beacham, Terry D.; Withler, Ruth E. 2018-06-21 Population structure of three ecotypes of Oncorhynchus nerka (sea-type Sockeye Salmon, lake-type Sockeye Salmon, and Kokanee) in the Fraser River and Columbia River drainages was examined with microsatellite variation, with the main focus as to whether Kokanee population structure within the Fraser River drainage suggested either a monophyletic or polyphyletic origin of the ecotype within the drainage. Variation at 14 microsatellite loci was surveyed for sea-type and lake-type Sockeye Salmon and Kokanee sampled from 121 populations in the two river drainages. An index of genetic differentiation, FST, over all populations and loci was 0.087, with individual locus values ranging from 0.031 to 0.172. Standardized to an ecotype sample size of 275 individuals, the least genetically diverse ecotype was sea-type Sockeye Salmon with 203 alleles, whereas Kokanee displayed the greatest number of alleles (260 alleles), with lake-type Sockeye Salmon intermediate (241 alleles). Kokanee populations from the Columbia River drainage (Okanagan Lake, Kootenay Lake), the South Thompson River (a major Fraser River tributary) drainage populations, and the mid-Fraser River populations all clustered together in a neighbor-joining analysis, indicative of a monophyletic origin of the Kokanee ecotype in these regions, likely reflecting the origin of salmon radiating from a refuge after the last glaciation period. However, upstream of the mid-Fraser River populations, there were closer relationships between the lake-type Sockeye Salmon ecotype and the Kokanee ecotype, indicative of the Kokanee ecotype evolving independently from the lake-type Sockeye Salmon ecotype in parallel radiation. Kokanee population structure within the entire Fraser River drainage suggested a polyphyletic origin of the ecotype within the drainage. Studies employing geographically restricted population sampling may not outline accurately the phylogenetic history of salmonid ecotypes.

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