Evaluating fisheries management options under large systematic changes in predator-prey interactions

最常用于提供渔业管理建议的定量模型假定，在很长一段时间内，控制鱼类种群动态的生态条件是稳定的。在许多区域，捕食鱼类的关键物种出现了非常大的系统性趋势，关键被捕食物种也出现了大幅波动。已经有相当多的理论建模研究，研究捕食者-猎物相互作用对商业和娱乐价值物种的可能影响。然而，已经有相对较少的注意力，制定股票评估建模方法和管理战略评价（MSE）的方法，可以提供直接的建议，渔业管理人员和决策者的情况下，有很大的明显变化的主要猎物和捕食物种的主要娱乐和商业鱼类。我试图调查系统的变化，捕食者-猎物的相互作用对鱼类种群动态的影响，在加拿大渔业的各种中，似乎有很大的变化，猎物和捕食者的人口。我将使用MSE方法来做到这一点，其中我将建立新的鱼类种群种群动态模型，以解释许多加拿大渔业中捕食者和猎物种群变化可能产生的影响，这些渔业中的关键捕食者和猎物种群最近发生了重大变化。/或猎物物种种群。我将寻求测试的假设可能的影响，捕食物种丰度和捕食率的变化对自然死亡率和猎物物种丰度的变化对这些鱼类种群的增长率的变化。因此，我提出的研究计划的长期目标是调查的捕食者-猎物的相互作用对鱼类种群的影响，使用管理策略评估（MSE）的框架。我试图开发人口动态模型，使用贝叶斯统计技术来测试假设的影响捕食者-猎物的相互作用对捕捞鱼类种群的人口动态，并将这些模型应用于中小企业，以确定政策选择，是强大的未来捕食率和猎物可用性的合理变化的情况。我计划测试的假设，大系统的变化（a）pinniped（例如，海豹物种）种群丰度和（B）饲料物种的可用性将通过改变，例如，增长率和自然死亡率（M）。为了进行研究，我将调查（1）空间异质性和历史和未来可能的趋势捕食风险和丰富的猎物物种可以共同修改（a）人口动态，（B）最大可持续产量（MSY）的参考点，通常用于指导政策建议，和（c）不同的管理方法的适用性的各种收获的鱼类物种。此外，我将调查（2）如何管理方法可以设计，以适应系统的变化，丰富的关键捕食者和猎物，可能会修改鱼类种群的弹性开发。我计划两个案例研究：项目#1：使用MSE方法来评估长期枯竭的不列颠哥伦比亚省内水岩鱼种群的政策选择。项目二：使用MSE方法来评估政策选项的顶端捕食者下大的变化，饲料物种丰富度：下弗雷泽河白色鲟鱼。在这些案例研究中，将评估关键捕食者和被捕食者种群的系统性变化如何影响鱼类种群的情景，以确定适当应对这种变化的渔业监测和捕捞控制政策选择。

The quantitative models most commonly applied to provide fisheries management advice presume stability in ecological conditions governing fish population dynamics over long periods of time. In many regions there have been very large systematic trends in key species that prey on fishes and large fluctuations in key prey species. There has been considerable theoretical modeling research into studying the possible impacts of predator-prey interactions on commercially and recreationally valuable species. However, there has been relatively little attention given to developing stock assessment modeling approaches and management strategy evaluation (MSE) approaches that can offer direct advice to fisheries managers and policy makers in situations where there have been large apparent changes in key prey and predator species of key recreational and commercial fishes. I seek to investigate the influence of systematic changes in predator-prey interactions on fish population dynamics for a variety of Canadian fisheries in which there appears to have been substantial changes in the prey and predator populations. I will do so using a MSE approach in which I will build new population dynamics models of fish populations that account for the possible influence of changes in predator and prey populations in a number of Canadian fisheries where there have been substantial recent changes in key predator and/or prey species populations. I will seek to test hypotheses about the possible effects of changes in predator species abundance and predation rates on natural mortality rates and changes in prey species abundance on changes in growth rates for these fish populations. The long-term objective of my proposed research program is thus to investigate the influence of predator-prey interactions on fish populations using the framework of management strategy evaluation (MSE). I seek to develop population dynamics models, use Bayesian statistical techniques to test hypotheses about the influence of predator-prey interactions on the population dynamics of harvested fish populations and apply these models in MSEs to identify policy options that are robust to scenarios for plausible changes in future predation rates and prey availability. I plan to test the hypotheses that large systematic changes in (a) pinniped (e.g., seal species) population abundance and (b) forage species availability will modify the influence of fisheries exploitation on the population dynamics of harvested fish populations via changes in, e.g., growth and natural mortality rates (M). To undertake the research I will investigate how (1) spatial heterogeneity and historic and possible future trends in predation risk and the abundance of prey species can jointly modify (a) the population dynamics, (b) the maximum sustainable yield (MSY) reference points that are commonly used to guide policy advice, and (c) the suitability of different management approaches for a variety of harvested fish species. In addition I will investigate (2) how management approaches can be designed to adapt to systematic changes in the abundance of key predator and prey that may modify a fish stock’s resilience to exploitation. I plan two case studies: Project #1: Using an MSE approach to evaluate policy options for chronically-depleted B.C. inside water rockfish stocks. Project #2: Using a MSE approach to evaluate policy options for an apex predator under large changes in forage species abundance: Lower Fraser River white sturgeon. In these case studies, scenarios on how systematic changes in key predator and prey populations can affect fish stocks will be assessed in order to identify fisheries monitoring and harvest control policy options that respond appropriately to such changes.