Data from: Does density influence relative growth performance of farm, wild, and F1 hybrid Atlantic salmon in semi-natural and hatchery common garden conditions?

The conditions encountered by Atlantic salmon, Salmo salar L., in aquaculture are markedly different from the natural environment. Typically, farmed salmon experience much higher densities than wild individuals, and may therefore have adapted to living in high densities. Previous studies have demonstrated that farmed salmon typically outgrow wild salmon by large ratios in the hatchery, but these differences are much less pronounced in the wild. Such divergence in growth may be explained partly by the offspring of wild salmon experiencing higher stress and thus lower growth when compared under high-density farming conditions. Here, growth of farmed, wild and F1 hybrid salmon was studied at contrasting densities within a hatchery and semi-natural environment. Farmed salmon significantly outgrew hybrid and wild salmon in all treatments. Importantly, however, the reaction norms were similar across treatments for all groups. Thus, this study was unable to find evidence that the offspring of farmed salmon have adapted more readily to higher fish densities than wild salmon as a result of domestication. It is suggested that the substantially higher growth rate of farmed salmon observed in the hatchery compared with wild individuals may not solely be caused by differences in their ability to grow in high-density hatchery scenarios.大西洋鲑（Atlantic salmon, Salmo salar L.）在水产养殖过程中所经历的环境条件，与自然生存环境存在显著差异。通常，养殖鲑的种群密度远高于野生个体，因此可能已适应高密度生存环境。既往研究表明，在孵化场环境中，养殖鲑的生长速度通常远超野生鲑，但这种生长差异在野生环境中已大幅减弱。这种生长表现的分化，部分可归因于在高密度养殖条件下，野生鲑的后代面临更高的应激水平，进而生长速率更低。本研究在孵化场与半自然环境中，设置不同密度梯度，对养殖鲑、野生鲑及F1杂交鲑（F1 hybrid salmon）的生长情况展开研究。结果显示，在所有处理组中，养殖鲑的生长速度均显著高于杂交鲑与野生鲑。但值得注意的是，所有类群的反应规范（reaction norms）在不同处理间均无显著差异。因此，本研究未发现证据表明，经驯化的养殖鲑后代，相比野生鲑后代更易适应更高的鱼类养殖密度。本研究提示，孵化场中观测到的养殖鲑生长速度远高于野生个体的现象，可能并非仅由二者在高密度孵化场环境中的生长能力差异所导致。