Data from: Species’ ecological functionality alters the outcome of fish stocking success predicted by a food-web model

Fish stocking is used worldwide in conservation and management but its effects on food-web dynamics and ecosystem stability are poorly known. To better understand these effects and predict the outcomes of stocking, we used an empirically validated network model of a well-studied lake ecosystem. We simulate two stocking scenarios with two native fish species valuable for fishing. In the first scenario, we stock planktivorous fish (whitefish) larvae in the ecosystem. This leads to 1% increase in adult whitefish biomasses and decreases the biomasses of the top predator (perch). In the second scenario, we also stock perch larvae in the ecosystem. This decreases the planktivorous whitefish and the oldest top predator age class biomasses, and destabilizes the ecosystem. Our results demonstrate that the effects of stocking depend on the species’ position in the food web and thus cannot be assessed without considering interacting species. We further show that stocking can lead to undesired outcomes from both management and conservation perspectives. The gains of stocking can remain minor and have adverse effects on the entire ecosystem.

鱼类放养（Fish Stocking）已在全球范围内被广泛应用于物种保护与渔业管理领域，但其对食物网（food web）动态及生态系统稳定性（ecosystem stability）的影响却尚未得到充分认知。为深入阐明此类影响并预判鱼类放养的实施效果，本研究采用了经实证验证的、针对某一已被广泛研究的湖泊生态系统的网络模型。我们针对两种兼具重要渔业价值的本土鱼类，设置了两类放养情景开展模拟实验。在第一类情景中，我们向该生态系统投放浮游食性鱼类（planktivorous fish）的幼体，即白鱼（whitefish）。该操作可使成年白鱼的生物量提升1%，同时会降低顶级捕食者——鲈鱼（perch）的生物量。在第二类情景中，我们额外向该生态系统投放鲈鱼（perch）的幼体。该操作会降低浮游食性白鱼以及最年长年龄组顶级捕食者的生物量，并破坏生态系统的稳定性。本研究结果表明，鱼类放养的影响取决于物种在食物网中的所处位置，因此若不考虑物种间的相互作用，便无法准确评估其实施效果。此外，本研究还证实，从渔业管理与物种保护的双重视角出发，鱼类放养均可能产生非预期的负面结果：其所能带来的收益可能微乎其微，反而会对整个生态系统造成不利影响。