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 were 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, the present 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 to 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.）在水产养殖中所经历的环境条件，与自然栖息环境存在显著差异。通常而言，养殖鲑的种群密度远高于野生个体，因此或已适应高密度生存环境。既往研究表明，养殖鲑在孵化场中的生长速率通常远超野生鲑，但在自然环境中，这类生长差异会大幅减弱。这种生长分化的成因，部分可归结为：在高密度养殖环境下，野生鲑的后代会承受更高的生理应激，进而导致生长速率降低。本研究针对孵化场与半自然环境中的两类密度梯度条件，探究了养殖鲑、野生鲑及其F1杂交鲑的生长表现。结果显示，在所有处理组中，养殖鲑的生长速度均显著优于杂交鲑与野生鲑。但值得关注的是，所有组别在不同处理条件下的反应规范（reaction norms）均保持一致。因此，本研究未找到证据表明，经驯化的养殖鲑后代，相较于野生鲑后代，更能适应更高的鱼类养殖密度。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这一现象，未必仅由二者在高密度孵化场环境中的生长能力差异所造成。