The Potential Biological Removal (PBR) level serves as a threshold for management of marine mammal–fishery interactions under the US Marine Mammal Protection Act. The PBR protocol involves classifying fisheries based on the ratio of recent average bycatch mortality to PBR. A simulation-based framework is developed that quantifies the probability of incorrectly concluding that average bycatch mortality exceeds PBR (i.e., a false positive) or incorrectly concluding that average bycatch mortality is less than PBR (i.e., a false negative), with application to the US stock of gray seals in the northwest Atlantic, a stock for which human-caused mortality levels are approaching PBR. The application to this stock of northwest Atlantic gray seals is complicated by the transboundary nature of the population. Consequently, the analyses are based on a population model that includes the US stock and the component of the Canadian stock off southern Nova Scotia, fitted to available data using Bayesian methods. The total error (i.e., false positive or false negative) probability is found to be largely independent of the coefficient of variation (CV) for estimates of bycatch mortality, whereas this probability is an increasing function of the CV for estimates of abundance. For gray seals, a CV for the estimates of abundance of ∼0.2 appears to balance the reduction in the total error probability versus the cost of surveys with greater sampling effort and more precise estimates of abundance.

根据美国海洋哺乳动物保护法，潜在生物去除 (PBR) 水平是管理海洋哺乳动物与渔业相互作用的阈值。PBR 协议涉及根据近期平均兼捕死亡率与 PBR 的比率对渔业进行分类。开发了一个基于模拟的框架，该框架量化了错误得出平均兼捕死亡率超过 PBR（即假阳性）或错误得出平均兼捕死亡率低于 PBR（即假阴性）结论的概率，并将其应用于美国西北大西洋的灰海豹种群，该种群的人为死亡率接近 PBR。由于种群的跨界性质，对这种西北大西洋灰海豹种群的应用变得复杂。最后，这些分析基于一个人口模型，该模型包括美国种群和新斯科舍省南部的加拿大种群，并使用贝叶斯方法拟合可用数据。发现总误差（即假阳性或假阴性）概率在很大程度上独立于估计兼捕死亡率的变异系数（CV），而该概率是估计丰度的 CV 的递增函数。对于灰海豹，丰度估计值的 CV 约为 0.2 似乎可以平衡总错误概率的降低与调查成本的降低，以及更多的抽样工作和更精确的丰度估计。发现假阳性或假阴性）概率在很大程度上独立于估计兼捕死亡率的变异系数 (CV)，而该概率是估计丰度的 CV 的递增函数。对于灰海豹，丰度估计值的 CV 约为 0.2 似乎可以平衡总错误概率的降低与调查成本的降低，以及更多的抽样工作和更精确的丰度估计。发现假阳性或假阴性）概率在很大程度上独立于估计兼捕死亡率的变异系数 (CV)，而该概率是估计丰度的 CV 的递增函数。对于灰海豹，丰度估计值的 CV 约为 0.2 似乎可以平衡总错误概率的降低与调查成本的降低，以及更多的抽样工作和更精确的丰度估计。