Apex Predators in the Central Pacific: An Ecosystem Approach

目前渔业造成的死亡率与被捕捞物种漫长的进化史上的任何情况都不同，因此，渔业是一种强大的生态力量。 将渔业影响理解为扰动的原因提供了关于调节远洋生态系统结构和功能的生态过程的重要经验教训。 上一个项目，Apex Predators in Pelagic Ecosystems，重点是在三个尺度上基于建模分析的中北太平洋（CNP）生态系统中的营养相互作用： 个体鱼类的生物能量学、捕食者-被捕食者相互作用和生态系统模型。 金枪鱼、长嘴鱼和鲨鱼延绳钓渔业的生态影响一直是所有三个模型开发领域的主题。 主要的教训是：1。 特征营养个体发育是一个关键组成部分，建立有效的模型，这个系统的强烈重叠使用的猎物资源和行会内捕食，和2。 渔业已成为并将继续成为CNP营养结构变化的主要原因。 该项目将支持第一个项目的继续和扩大。 Kitterman博士和合作者将开发模型，可以评估渔业影响在食物网动态中的作用，扩大到包括与大规模环境影响的相互作用，如ENSO，PDO，和/或气候变化动力学，并使用由此产生的模型作为评估资源管理政策的基础，这些政策可以改变生态系统结构，功能 三个主要目标将追求：实验方法建模。 他们开发了一个模型的营养相互作用和渔业影响的中北太平洋（CNP）的基础上，部分合并人口规模的数据与食物网信息和渔业发展的历史。 在中南太平洋（CSP）存在一个生态类似物，那里的渔业发展较晚。 研究人员将使用CNP方法开发CSP模型，然后对渔业发展引起的营养变化进行相当于独立的重复分析。 合并这些模型创建了一个单一的工具，可以评估在大规模背景下表达的局部效应。 将渔业定性为新的捕食者，可以评估食物网中的强烈相互作用和渔业效应产生的复杂反馈机制。 建模包括环境驱动因素。 他们将实施环境强迫由于ENSO，PDO和/或全球变化的影响，在我们的CNP，CSP模型和类似的热带太平洋东部（ETP）的模式，通过国家生态分析和综合中心（NCEAS）赞助的合作开发。 调查人员将使用统计方法来评估种群数据中的异常情况，作为区分渔业影响与改变初级生产率及其在较高营养水平生产中表达的环境强迫影响的基础。 副渔获物和生态相互作用。 主要的养护问题围绕着这些海洋生态系统中受到威胁或濒危的海龟、鸟类、鲨鱼和长嘴鱼的副渔获物。 博士，Kitterman和同事将使用“情景”的方法来模拟替代管理行动，渔业开发过程中的变化，其随之而来的生态变化及其社会经济后果的可能反应。 基本的生态系统模拟模型现在包括利用鱼价格加上就业、养护和/或生态系统管理目标权重对后者进行评估的能力。

The current levels of mortality owing to fisheries are unlike anything in the long evolutionary history of exploited species and, therefore, that fisheries are a powerful ecological force. Understanding fishery effects as causes of perturbation offers important lessons about the ecological processes that regulate structure and function of pelagic ecosystems. The previous project, Apex Predators in Pelagic Ecosystems, focused on trophic interactions in the central north Pacific (CNP) ecosystem based on modeling analyses at three scales: bioenergetics of individual fish species, predator-prey interactions and ecosystem models. The ecological effects of long-line fisheries for tunas, billfishes and sharks has been a consistent theme in all three areas of model development. The major lessons were that: 1. Characterizing trophic ontogeny was a key component to building effective models for this system of strongly overlapping use of prey resources and intra-guild predation, and 2. Fisheries have become and continue as the main cause of change in trophic structure of the CNP. This project will support continuation and expansion of the first project. Dr. Kitchell and collaborators will develop models that can evaluate the role of fishery effects in food web dynamics, expand that to include interactions with large-scale environmental effects such as those due to ENSO, PDO, and/or climate change dynamics and use the consequent models as a basis for evaluating resource management policies that can change ecosystem structure and function. Three major objectives will be pursued: Experimental Approach to Modeling. They have developed a model of trophic interactions and fishery effects for the central north Pacific (CNP) based, in part, on merging population-scale data with food web information and the history of fishery development. An ecological analogue exists in the central south Pacific (CSP) where fishery development occurred at a later time. The researchers will use the CNP approach to develop a CSP model, then conduct the equivalent of an independent, replicate analysis of the trophic changes owing to fishery development. Merging these models creates a single tool that allows evaluation of local effects expressed in a large-scale context. Characterizing fisheries as the equivalent of new predators allows an evaluation of .strong interactions in food webs and the complex feedback mechanisms that emerge from fishery effects. Modeling to Include Environmental Drivers. They will implement environmental forcing due to ENSO, PDO and/or global change effects expressed in our models of the CNP, CSP and a similar model of the eastern tropical Pacific (ETP) developed through collaboration sponsored by the National Center for Ecological Analysis and Synthesis (NCEAS). The investigators will use statistical approaches that evaluate anomalies in the population data as the basis for differentiating effects of the fisheries from those of the environmental forcing that alters primary production rates and its expression in production of higher trophic levels. Bycatch and Ecological Interactions. Major conservation issues revolve around bycatch of threatened or endangered turtles, birds, sharks and billfishes in these pelagic ecosystems. Dr, Kitchell and co-workers will use a "scenarios" approach to simulation of alternative management actions, the likely responses of changes in fishery exploitation processes, their consequent ecological changes and their socioeconomic consequences. The basic Ecosim model now includes the capacity to evaluate the latter using inputs of fish prices plus weighting for goals based on employment, conservation and/or ecosystem management.