Conservation efforts have mainly been focused on depleted species or populations, but many formerly reduced marine mammal populations have recovered to historical abundances. This calls for new management strategies and new models for ecological risk assessment that incorporate local density dependence and multiple environmental stressors. The harbor seal metapopulation in Swedish and Danish waters has increased from about 2500 to 25,000 over the past 40 yr. Trend analysis based on aerial survey data and somatic growth curves indicates that the population is close to carrying capacity. We performed a population viability analysis based on realistic life history parameters and investigated a range of potential scenarios caused by future stressors. If the population is able to resume its high intrinsic rate of increase at about 11% annually, when pushed down below carrying capacity, it can also sustain additional mortality such as modest hunting and infrequent epizootics. However, if xenobiotics will cause even a slight reduction in average fecundity, the population becomes significantly more vulnerable. In the absence of epizootics, and given full reproductive capacity, hunting of a few hundred animals annually is not harmful to the long‐term persistence of the population. Nevertheless, a slight decrease in growth potential, for example, caused by exposure to endocrine disruptors, makes even limited hunting risky. Our study shows how an apparently stable and abundant marine mammal population can be close to a point of rapid population decline. Thus, careful monitoring of population size, growth rate, health, and exposure to xenobiotics as well as recording of the age and sex structure of the hunt is required to avoid repeating the history of overexploitation and another population collapse.

中文翻译：

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过度利用看似稳定的海豹种群的风险：多重压力源和狩猎的影响

保护工作主要集中在枯竭的物种或种群上，但许多以前减少的海洋哺乳动物种群已恢复到历史丰富水平。这就要求采用新的管理策略和新的生态风险评估模型，其中应纳入局部密度依赖性和多种环境压力因素。在过去的40年中，瑞典和丹麦水域的海豹种群数量从大约2500增加到25,000。根据航测数据和体细胞生长曲线进行的趋势分析表明，人口接近承载能力。我们根据现实的生活史参数进行了种群生存力分析，并研究了未来压力源导致的一系列潜在情景。如果人口能够以每年约11％的速度恢复其高固有增长率，如果将其推低至承载力以下，它还可以维持额外的死亡率，例如适度的狩猎和罕见的动物流行病。但是，如果异生素甚至会导致平均生育力略有下降，那么人口将变得更加脆弱。在没有动物流行病的情况下，并具有充分的繁殖能力，每年猎杀数百只动物对人口的长期存续没有害处。然而，例如由于暴露于内分泌干扰物而导致的生长潜力略有下降，甚至使有限的狩猎风险也成为可能。我们的研究表明，看似稳定和丰富的海洋哺乳动物种群如何接近种群迅速减少的点。因此，请仔细监控人口规模，增长率，健康状况，