Fish stocking is commonly used to enhance recreational fisheries; however, the side effects of stocking at the ecosystem scale have rarely been tested. Avian predators, because of their high position in food webs, can serve as indicators of environmental change, including prey-species abundance. The scope of this study was to understand whether recent changes in northern pike (Esox lucius) stocking on a national scale could cascade through food webs and significantly shape the diet of a predator––the white-tailed eagle (Haliaeetus albicilla). The stocking of pike in state-owned waters in Lithuania has increased two- to threefold since 2005. A significant increase in the proportion of pike in the breeding-season diet of the white-tailed eagle has also been observed. We explain the increase in pike in the predator’s diet as being a causal consequence of pike stocking. We encourage consideration of the entire food web when launching/terminating recreational fish stocking programmes.

鱼类放养通常用于增强休闲渔业；但是，很少对生态系统规模的放养副作用进行测试。禽类天敌在食物网中的地位很高，可以作为环境变化的指标，包括猎物种类的丰富度。这项研究的目的是了解全国范围内北梭鱼（Esox lucius）近期种群的变化是否可以通过食物网级联并显着影响捕食者白尾鹰（Haliaeetus albicilla）的饮食。）。自2005年以来，立陶宛国有水域中的白斑狗鱼种群增加了2到3倍。白尾鹰繁殖季节饮食中的白斑狗鱼比例也显着增加。我们将食肉动物日粮中白斑狗的增加解释为是白斑狗鱼放养的因果结果。我们鼓励在启动/终止休闲鱼类种群计划时考虑整个食物网。