Inland fisheries face increasing threats to their sustainability. Despite speculation that depensation may exacerbate the effects of stressors on population resiliency, depensation has not been empirically explored in freshwater fisheries. Declining productivity of Walleye Sander vitreus populations in northern Wisconsin foreshadows an underlying change in naturally reproduced juvenile Walleye survival. We used long-term stock and recruitment data from lakes in the Ceded Territory of Wisconsin to quantify density-dependent trends in juvenile Walleye survival and tested for the prevalence of depensation using the q parameter of Liermann and Hilborn (1997). Of 82 Walleye populations evaluated, about half exhibited depensatory recruitment. An analysis of the global q for all populations examined suggested that the posterior probability of depensatory dynamics was about 0.89. In addition, there were few clear cases of compensation—most populations exhibited weak density dependence. The general lack of strong compensatory recruitment across Walleye populations could leave these stocks vulnerable to stressors and unresponsive to rehabilitation. We present multiple lines of evidence to suggest that depensation is a plausible phenomenon explaining declines in Walleye populations in the Ceded Territory of Wisconsin and may be implicated in other invisible collapses of freshwater fisheries.

中文翻译：

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淡水渔业依赖的经验证据

内陆渔业的可持续性面临越来越大的威胁。尽管推测转移可能会加剧压力因素对种群恢复力的影响，但尚未在淡水渔业中对转移进行实证研究。威斯康星州北部Walleye Sander 玻璃体种群生产力的下降预示着自然繁殖的 Walleye 幼鱼存活率的潜在变化。我们使用来自威斯康星州割让领地湖泊的长期种群和补充数据来量化幼年角膜白斑存活率的密度依赖性趋势，并使用Liermann 和 Hilborn (1997)的q参数测试了退化的流行率。在评估的 82 个角膜白斑种群中，大约一半表现出依赖招募。全球q分析对于所有检查的人群，表明依赖动力学的后验概率约为 0.89。此外，很少有明确的补偿案例——大多数种群表现出弱的密度依赖性。Walleye 种群普遍缺乏强有力的补偿性招募，这可能会使这些种群容易受到压力源的影响，并且对康复无反应。我们提出了多条证据，表明依赖是一种合理的现象，可以解释威斯康星割让领地的角膜白斑种群数量下降，并且可能与其他无形的淡水渔业崩溃有关。