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Population Structure and Stock Identification of Steelhead in Southern British Columbia, Washington, and the Columbia River Based on Microsatellite DNA Variation
Author(s) -
Beacham Terry D.,
Pollard Susan,
Le Khai D.
Publication year - 1999
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/1548-8659(1999)128<1068:psasio>2.0.co;2
Subject(s) - microsatellite , population , stock (firearms) , fishery , drainage basin , genetic variation , geography , biology , population genetics , ecology , allele , demography , archaeology , cartography , biochemistry , sociology , gene
The purpose of this study was to describe population structure and determine the potential for genetic stock identification for steelhead Oncorhynchus mykiss in British Columbia using microsatellite DNA markers. Variation at eight microsatellite DNA loci ( Oki200, Omy77, Ots1, Ots3, Ssa85, Ots100, Ots103 , and Ots108 ) was surveyed in approximately 1,500 steelhead from 22 populations in southern British Columbia, Washington, and the Columbia River drainage as well as in more than 450 steelhead from two commercial salmon fisheries conducted off the southwest coast of Vancouver Island. Nine populations were sampled for two or more years, and variation in allele frequencies among populations and regions was, on average, about 3.7 times greater than annual variation within populations. Regional structuring of populations was apparent, with Thompson River, upper Fraser River, and Columbia River populations forming distinct groups. Significant differences in allele frequencies were observed among regional stock groups at all loci. After variation within populations was accounted for, variation among regions was the greatest source of the remaining variation (4.4%), followed by variation among populations within regions (3.1%) and variation among years within populations (2.0%). The overall classification accuracy of single individuals to five regional groups using a jackknifed discriminant analysis was 80%. Simulated mixed‐stock samples suggested that variation at the eight microsatellite DNA loci surveyed should provide relatively accurate and precise estimates of stock composition for fishery management applications. Analyses of commercial marine fisheries samples indicated that during 1994–1996 more than 85% of the steelhead sampled in a directed chum salmon fishery off the mouth of the Nitinat River originated in the Fraser River drainage with the majority of steelhead from the Thompson River. However, in 1997, steelhead of U.S. origin were estimated to have composed 60% of the samples, and the Canadian component was largely of Fraser River steelhead, possibly reflecting anomalies associated with climatic variation. Estimated stock composition of samples from the 1997 sockeye salmon fishery in Barkley Sound indicated that the majority (71%) of steelhead was of Vancouver Island origin with the remainder being of U.S. origin.