Canadian Journal of Fisheries and Aquatic Sciences, Ahead of Print.
Decreases in size at maturation in harvested fish populations can reduce productivity and resilience. Delineating the causes for these changes in maturation is challenging. We assessed harvest and large-scale ecosystem variability as causes for changes in maturation in four Lake Erie fishes. Regulated harvests of yellow perch (Perca flavescens) and walleye (Sander vitreus) are greater than unregulated harvests of white perch (Morone americana) and white bass (Morone chrysops). Our assessment considered cohort data from 1991 to 2012 for each species. We used a conceptual model of harvest-induced plasticity to show that changes in female length at 50% maturity (L 50) were unrelated to harvest intensity in all species. We then demonstrated that changes in female L 50 among cohorts were synchronous across species. Post hoc analysis of variables capturing year-to-year variation in climatic and lake conditions suggested L 50 was larger when water levels were near the norm for the study period and smaller at low and high levels. We conclude that changes in L 50 were most strongly related to ecosystem changes unrelated to harvest intensity.

中文翻译：

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具有不同收获历史的四种伊利湖鱼的成熟期长度同步变化

《加拿大渔业和水生科学杂志》，印刷前。
收获鱼类种群成熟时尺寸的减小会降低生产力和弹性。描绘出这些成熟变化的原因是具有挑战性的。我们评估了收获和大规模的生态系统变异性，作为造成伊利湖四类鱼类成熟度变化的原因。黄色鲈鱼（Perca flavescens）和大眼鲷（Sander vitreus）的规定收成要大于白色鲈鱼（美洲莫罗那）和白色鲈鱼（Morone chrysops）的不受监管的收成。我们的评估考虑了1991年至2012年每个物种的队列数据。我们使用了收获诱导可塑性的概念模型来表明，在所有物种中，成熟度为50％（L 50）时雌性长度的变化与收获强度无关。然后，我们证明了队列中雌性L 50的变化在物种之间是同步的。对捕获气候和湖泊条件逐年变化的变量进行事后分析表明，当水位在研究期间接近正常水平时，L 50较大，而在低水位和高水位时，L 50较小。我们得出结论，L 50的变化与生态系统变化最密切相关，而生态系统变化与收获强度无关。