Genetic effects of marine stock enhancement: a case study based on the highly piscivorous Japanese Spanish mackerel

Abstract

Abstract:We used a before-after control-impact design to quantify the genetic effects of the large piscivorous Japanese Spanish mackerel (Scomberomorus niphonius) stock enhancement program on wild populations in the Seto Inland Sea. Samples of 1424 wild and 230 hatchery fish collected from 13 sites around Japan were genotyped using five microsatellite markers. A total of 758 wild and 103 hatchery fish were sequenced for the mitochondrial DNA D-loop region. The population structure of Japanese Spanish mackerel was panmictic around Japan. Hatchery fish had significantly lower genetic diversity indices than did wild fish. However, there was no significant change in any of the diversity indices in the Seto Inland Sea, despite the substantial genetic mixing proportion of hatchery-origin genes (7.8%-14.5% from releases in 2001 and 2002), a conclusion supported by simulations. The estimated effective population size was surprisingly small (ϳ430-970) but stable in the Seto Inland Sea compared with the large census size. A Ryman-Laikre effect was not likely in the Japanese Spanish mackerel.Résumé : Nous avons utilisé un schéma contrôle-incidence avant-après pour quantifier les effets génétiques du programme d'amélioration des stocks de thazard oriental (Scomberomorus niphonius), un grand poisson piscivore, sur les populations sauvages dans la mer intérieure de Seto. Des échantillons de 1424 poissons sauvages et 230 poissons d'élevage prélevés en 13 endroits différents au Japon ont été génotypés à l'aide de cinq marqueurs microsatellites. Un total de 758 poissons sauvages et 103 poissons d'élevage ont fait l'objet d'un séquençage de la région de la boucle D de l'ADN mitochondrial. La structure de la population de thazard oriental était panmictique dans la région du Japon. Les poissons d'élevage présentaient des indices de diversité génétique significativement plus faibles que les poissons sauvages. Cela dit, aucun indice de diversité ne présentait de variation significative dans la mer intérieure de Seto, malgré l'importante proportion de mélange génétique de gènes issus d'écloserie (7,8-14,5 % dans les lâchés en 2001 et 2002), une conclusion appuyée par les simulations. La taille effective estimée de la population était étonnamment faible (ϳ430-970), bien que stable, dans la mer intérieure de Seto comparativement à la grande taille recensée. La présence d'un effet Ryman-Laikre chez les thazards orientals était peu probable. [Traduit par la Rédaction]

A Genetic Assessment of a Red Drum, Sciaenops ocellatus, Stock Enhancement Program

“…Similar to this study, stock enhancement programs for Pacific herring in northern Japan (Kitada et al ), Japanese Spanish mackerel off the western coast of Japan (Nakajima et al ), and red drum in the Gulf of Mexico (Carson et al ) also reported no change in genetic diversity metrics despite measurable contributions of stocked individuals to the local spawning population (Pacific herring) and subadult populations (Japanese Spanish mackerel and red drum) in the wild. These programs incorporated aspects of the “Responsible Approach” (Blankenship and Leber ) by using native broodstock and periodically rotating these individuals out of production to increase hatchery effective population size per generation.…”

Recent genetic changes in enhanced populations of sea trout (Salmo truttam.trutta) in the southern Baltic rivers revealed with SNP analysis

“…Utter et al 1987;Wenne 1992;Poteaux and Berrebi 1997;Halvorson et al 2001;Was et al 2004;Poćwierz-Kotus et al 2007;Wenne et al 2007;Filipowicz et al 2008;Beaumont et al 2010;Wenne et al 2011;Kohout et al 2013;Nakajima et al 2014). Microsatellites are regularly used in fisheries related applications and research (Was and Wenne 1998;Griffiths et al 2013;Perrier et al 2013;Pukk et al 2013;Bernaś et al 2014;Koljonen et al 2014;Thaulow et al 2014;Valiquette et al 2014).…”

Population panmixia and demographic expansion of a highly piscivorous marine fish Scomberomorus niphonius

“…Publicly available mtDNA‐CR sequences (305 bp without gaps and missing data, n = 720) and microsatellite genotypes at five loci ( n = 1331) in wild S. niphonius were used (Nakajima et al ., , b ), excluding the sample collected in South Korea and those of hatchery‐reared fish from the original data. All loci were scored by capillary electrophoresis using an ABI PRISM 3130xl Genetic Analyzer (Applied Biosystems; http://www.apliedbiosystems.com) with fluorescent dye‐labelled primers and there was no evidence for scoring error caused by stuttering, large allele dropout, or null alleles (Nakajima et al ., ). The samples were collected from major distribution areas in Japan during 2001–2010 ( Table and Fig .…”

“…The sample included some 2 year old fish, but they were matured. As no significant difference was found in the haplotype and allele frequencies (Nakajima et al ., ) by an exact test for population differentiation (Raymond & Rousset, ), the samples were combined within each sampling period and denoted as SIS_1 and SIS_2,. The other samples were young immature fish collected in Tosa Bay (TSB), Shibushi Bay (SBS), Kasasa (KSA), Ise Bay (ISB), Wakasa Bay (WKB) and Goto Island (GOT).…”