Complex life history behaviours like spawning migrations can complicate population assessments. However, predictable aggregation of populations at certain times of year (e.g. at spawning grounds) presents an effective way to sample species that are otherwise spatially widespread. From 2014 to 2019, a mark-recapture study on Green Bay northern pike (Esox lucius) entering a spawning wetland was used to estimate apparent survival and population size using Bayesian inference and the Cormack–Jolly–Seber model. Population estimates and apparent survival varied from 446 to 1949 and 0.22 (males in 2017) to 0.63 (males in 2015), respectively, among years. Apparent survival also increased with maximum mean daily water temperature. Estimated capture probability was consistently low across years (<30%) despite a sampling method with high capture efficiency of fish present at the wetland, suggesting Green Bay northern pike may be exhibiting low spawning site fidelity or other life history behaviours, like skipped spawning, which reduce their capture probability at a single wetland over time. Further, spawning site selection and timing may respond to water temperatures. Surveying multiple sites could further elucidate important life history traits while refining estimates of population size and structure in large systems.

中文翻译：

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估计下绿湾成年北梭子鱼 (Esox lucius) 的种群规模和存活率

繁衍迁徙等复杂的生活史行为会使种群评估复杂化。然而，在一年中的某些时间（例如在产卵场）可预测的种群聚集提供了一种对空间分布广泛的物种进行采样的有效方法。2014-2019年绿湾北梭子鱼（Esox lucius) 使用贝叶斯推理和 Cormack-Jolly-Seber 模型进入产卵湿地来估计表观存活率和种群规模。人口估计数和表观存活率分别从 446 到 1949 年和 0.22（2017 年男性）到 0.63（2015 年男性）在不同年份之间变化。表观存活率也随着每日平均最高水温的增加而增加。尽管采样方法对湿地中存在的鱼类具有高捕获效率，但估计捕获概率多年来一直很低（<30％），这表明绿湾北部梭子鱼可能表现出产卵地点保真度低或其他生活史行为，如跳过产卵，随着时间的推移，这会降低它们在单个湿地的捕获概率。此外，产卵地点的选择和时间可能会响应水温。