title: Effects of Large-Scale Releases on the Genetic Structure of Red Sea Bream (Pagrus major, Temminck et Schlegel) Populations in Japan.
abstract: Large-scale hatchery releases are carried out for many marine fish species worldwide; nevertheless, the long-term effects of this practice on the genetic structure of natural populations remains unclear. The lack of knowledge is especially evident when independent stock enhancement programs are conducted simultaneously on the same species at different geographical locations, as occurs with red sea bream (Pagrus major, Temminck et Schlegel) in Japan. In this study, we examined the putative effects of intensive offspring releases on the genetic structure of red sea bream populations along the Japanese archipelago by genotyping 848 fish at fifteen microsatellite loci. Our results suggests weak but consistent patterns of genetic divergence (F(ST) = 0.002, p < 0.001). Red sea bream in Japan appeared spatially structured with several patches of distinct allelic composition, which corresponded to areas receiving an important influx of fish of hatchery origin, either released intentionally or from unintentional escapees from aquaculture operations. In addition to impacts upon local populations inhabiting semi-enclosed embayments, large-scale releases (either intentionally or from unintentional escapes) appeared also to have perturbed genetic structure in open areas. Hence, results of the present study suggest that independent large-scale marine stock enhancement programs conducted simultaneously on one species at different geographical locations may compromise native genetic structure and lead to patchy patterns in population genetic structure.
authors.affiliation: The Research Institute of Marine Bioresources, Fukuyama University, Onomichi, 722-2101, Japan; University of Agder, N-4604, Kristiansand, Norway; Institute of Marine Research (IMR), Flødevigen, N-4817, His, Norway.
authors.forename: Enrique
authors.initials: E
authors.lastname: Blanco Gonzalez
authors.affiliation: Coastal Fisheries and Aquaculture Division, Seikai National Fisheries Research Institute, Fisheries Research Agency, Nagasaki, 851-2213, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Aritaki
authors.affiliation: University of Agder, N-4604, Kristiansand, Norway; Institute of Marine Research (IMR), Flødevigen, N-4817, His, Norway; Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Blindern, N-0316, Oslo, Norway.
authors.forename: Halvor
authors.initials: H
authors.lastname: Knutsen
authors.affiliation: The Research Institute of Marine Bioresources, Fukuyama University, Onomichi, 722-2101, Japan.
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Taniguchi
mesh_terms: D000818:Animals; D017756:Aquaculture / Q000379:methods; D005398:Fisheries / Q000379:methods; D005828:Genetics, Population / Q000379:methods; D005838:Genotype; D007564:Japan; D018895:Microsatellite Repeats / Q000235:genetics; D021541:Sea Bream / Q000235:genetics* / Q000254:growth & development*