The recovery of large carnivore species from over‐exploitation can have socioecological effects; thus, reliable estimates of potential abundance and distribution represent a valuable tool for developing management objectives and recovery criteria. For sea otters (Enhydra lutris), as with many apex predators, equilibrium abundance is not constant across space but rather varies as a function of local habitat quality and resource dynamics, thereby complicating the extrapolation of carrying capacity (K) from one location to another. To overcome this challenge, we developed a state‐space model of density‐dependent population dynamics in southern sea otters (E. l. nereis), in which K is estimated as a continuously varying function of a suite of physical, biotic, and oceanographic variables, all described at fine spatial scales. We used a theta‐logistic process model that included environmental stochasticity and allowed for density‐independent mortality associated with shark bites. We used Bayesian methods to fit the model to time series of survey data, augmented by auxiliary data on cause of death in stranded otters. Our model results showed that the expected density at K for a given area can be predicted based on local bathymetry (depth and distance from shore), benthic substrate composition (rocky vs. soft sediments), presence of kelp canopy, net primary productivity, and whether or not the area is inside an estuary. In addition to density‐dependent reductions in growth, increased levels of shark‐bite mortality over the last decade have also acted to limit population expansion. We used the functional relationships between habitat variables and equilibrium density to project estimated values of K for the entire historical range of southern sea otters in California, USA, accounting for spatial variation in habitat quality. Our results suggest that California could eventually support 17,226 otters (95% CrI = 9,739–30,087). We also used the fitted model to compute candidate values of optimal sustainable population abundance (OSP) for all of California and for regions within California. We employed a simulation‐based approach to determine the abundance associated with the maximum net productivity level (MNPL) and propose that the upper quartile of the distribution of MNPL estimates (accounting for parameter uncertainty) represents an appropriate threshold value for OSP. Based on this analysis, we suggest a candidate value for OSP (for all of California) of 10,236, which represents 59.4% of projected K. © 2021 The Authors. The Journal of Wildlife Management published by Wiley Periodicals LLC on behalf of The Wildlife Society.

中文翻译：

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人居特征预测恢复的食肉动物的承载能力

从过度开发中恢复大型食肉动物物种可能产生社会生态影响；因此，对潜在丰度和分布的可靠估计是制定管理目标和恢复标准的宝贵工具。对于水獭（Enhydra lutris）而言，与许多先天性捕食者一样，整个空间的平衡丰度不是恒定的，而是随当地栖息地质量和资源动态而变化的，从而使从一个位置到另一个位置的承载能力（K）的推断复杂化。。为了克服这一挑战，我们开发了一种状态空间模型，用于研究南部水獭（E. l。nereis）的密度依赖性种群动态，其中K估计值是一系列物理，生物和海洋学变量的连续变化函数，所有这些变量都在精细的空间尺度上描述。我们使用了包括环境随机性在内的热流逻辑过程模型，并考虑到了与鲨鱼叮咬相关的密度无关的死亡率。我们使用贝叶斯方法将模型拟合到调查数据的时间序列，并补充了搁浅水獭死亡原因的辅助数据。我们的模型结果表明，在K处的预期密度可以根据局部测深法（距岸的深度和距离），底栖基质成分（岩石与软沉积物），海带冠层的存在，净初级生产力以及该区域是否在河口内来预测给定区域的水。除了依赖密度的增长减少外，过去十年来鲨鱼咬伤死亡率的上升也限制了人口的增长。我们利用栖息地变量和平衡密度之间的函数关系来估算K的估计值在美国加利福尼亚州南部水獭的整个历史范围内，说明了栖息地质量的空间变化。我们的结果表明，加利福尼亚州最终可以支持17,226只水獭（95％的CrI = 9,739–30,087）。我们还使用拟合模型为整个加利福尼亚州和加利福尼亚州内的区域计算最佳可持续人口数量（OSP）的候选值。我们采用基于仿真的方法来确定与最大净生产率水平（MNPL）相关的丰度，并提出MNPL估计值分布的上限四分位数（考虑参数不确定性）代表OSP的适当阈值。根据此分析，我们建议OSP的候选值（对于整个加利福尼亚州）为10236，占预计K的59.4％。©2021作者。Wiley Periodicals LLC代表野生动物协会出版的《野生动物管理杂志》。