Institut de Biologie Intégrative des Systèmes (IBIS), Université Laval, Québec, Quebec, G1V0A6, Canada.
Chaire de recherche sur les espèces aquatiques exploitées, Laboratoire des sciences aquatiques, Département des sciences fondamentales, Université du Québec à Chicoutimi, Chicoutimi, Quebec, G7H2B1, Canada.
Ecol Appl. 2019 Apr;29(3):e01857. doi: 10.1002/eap.1857. Epub 2019 Feb 26.
Worldwide, stocking of fish represents a valuable tool for conservation and maintenance of species exploited by recreational fishing. Releases of hatchery-reared fish are more and more recognized to have numerous demographic, ecological, and genetic impacts on wild populations. However, consequences on intraspecific trophic relationships have rarely been investigated. In this study, we assessed the impacts of supplementation stocking and resulting introgressive hybridization on the trophic niches occupied by stocked, local, and hybrid lake trout (Salvelinus namaycush) within populations of piscivorous and planktivorous ecotypes stocked from a wild piscivorous source population. We compared trophic niches using stable isotope analysis (δ C and δ N) and trophic position among the three genetic origins. Putative genetic effects were tested with phenotype-genotype association of "life history" ecological traits (body size, growth rate, condition index, and trophic niche) and genotypes (RADseq SNP markers) using redundant discriminant analysis (RDA). Results showed that sympatry resulting from the stocking of contrasting ecotypes is a risk factor for niche partitioning. Planktivorous populations are more susceptible to niche partitioning, by competitive exclusion of the local fish from a littoral niche to an alternative pelagic/profundal niche. Observed niche partitioning is probably a manifestation of competitive interactions between ecotypes. Our results emphasize that ecotypic variation should be considered for more efficient management and conservation practices and in order to mitigate negative impact of supplementation stocking.
在全球范围内，鱼类库存是保护和维持休闲渔业捕捞物种的宝贵工具。越来越多的人认识到，人工养殖鱼类的释放对野生种群具有众多人口统计学、生态学和遗传学影响。然而，很少有人研究其对种内营养关系的影响。在这项研究中，我们评估了补充放养和由此产生的入侵杂交对来自野生肉食性种群的肉食性和浮游生物食性种群中放养、本地和杂交湖鳟（Salvelinus namaycush）的营养生态位的影响。我们通过稳定同位素分析（δC 和 δN）和三种遗传来源的营养位比较了营养生态位。利用“生活史”生态特征（体型、生长率、条件指数和营养生态位）和基因型（RADseq SNP 标记）的表型-基因型关联，对潜在的遗传效应进行了测试，采用冗余判别分析（RDA）。结果表明，由于放养不同生态型而导致的同域共存是营养生态位分化的一个风险因素。浮游生物食性种群更容易发生营养生态位分化，因为本地鱼类被从滨岸浅水区排挤到替代的浮游/深水区。观察到的营养生态位分化可能是生态型之间竞争相互作用的表现。我们的研究结果强调，应考虑生态型的变异，以便更有效地管理和保护实践，并减轻补充放养的负面影响。
