Angling catch rates of Walleye Sander vitreus in many lakes across Alberta have increased dramatically in the past 20 years, following their collapse and then recovery after implementation of restrictive harvest regulations. With increased abundance, some anglers are concerned that Walleyes may negatively affect abundance of Northern Pike Esox lucius. To address this hypothesis, we looked at net catch data for each species from 352 surveys in 129 lakes across Alberta between 2000 and 2017. Results were equivocal. Netting data indicated that low‐density Northern Pike populations were not associated with high densities of Walleyes when grouped categorically. However, mixed‐model quantile regression did support a negative relationship for the two species, but the mechanism is unclear and the strength of the interaction is weak in most cases. In few lakes (≤10%), potentially acceptable reductions in Walleye densities may produce meaningful increases in Northern Pike but uncertainty is substantial. Future Walleye harvest experiments to reduce uncertainty and establish causation are warranted only if Northern Pike are already at moderate to high densities and large reductions in Walleyes (≥75%) are acceptable. For these reasons, increased Walleye harvest is not supported as a management tool for increasing Northern Pike populations or enhancing angler catch rates in Alberta.

中文翻译：

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艾伯塔省的北派克种群是否正受到角膜白斑病的威胁？

在过去的20年中，瓦利眼桑德玻璃体的垂钓率在崩溃后急剧增加，随后在实施限制性收割规定后又恢复了过去20年。随着垂钓者数量的增加，一些垂钓者担心角膜白斑可能对北派克ike鱼的数量产生负面影响。。为了解决这个假设，我们研究了2000年至2017年间在艾伯塔省129个湖泊中进行的352次调查中每种物种的净捕获量数据。结果是模棱两可的。网络数据表明，按分类分组时，低密度的北派克种群与高密度的角膜白斑无关。但是，混合模型分位数回归确实支持了这两种物种的负相关关系，但是在大多数情况下，机理尚不清楚，相互作用的强度也很弱。在少数几个湖泊（≤10％）中，大眼鲷密度的潜在可接受的降低可能会导致北派克山脉的有意义的增长，但不确定性很大。仅当北派克菌已经处于中等到高密度并且大范围减少角眼（≥75％）是可以接受的情况下，才有必要进行未来的角眼收获实验以减少不确定性并建立因果关系。由于这些原因，不支持使用增加的角膜白斑收成作为增加北派克种群或提高艾伯塔省垂钓者捕捞率的管理工具。