Apex Predators in the Pelagic Zone

在远洋食物网中对顶端捕食者的开发应该会在几个尺度上导致一系列生态变化。我们将确定顶端捕食者(大型金枪鱼、比目鱼和鲨鱼)及其一些主要猎物(鱿鱼、小型金枪鱼和幼金枪鱼)在中北太平洋(CNP)中上层食物网中的补偿反应动力学。我们将测试渔业引起的生长率变化、捕食者与猎物的相互作用(食物)、生活史特征，如大小或成熟年龄，以及鱼类群落的物种组成。食物网动态分析将被用来评估开发变化的生态后果。我们将使用与国家海洋渔业局火奴鲁鲁实验室合作提供的对长期数据集的回顾分析。对“脉冲”操纵的反应将来自对开发影响、猎物可获得性和环境影响(海洋制度变化)的重大、快速变化的最新证据的分析。对顶端捕食者种群“压力”操作的反应将来自NMFS维护的35-50年基本生物数据、生活史研究和渔获量数据的记录。当代的生长率、饮食、生活史特征和物种组成的数据将与1948年以来收集的数据进行比较。这项工作将使用三类分析工具。时间序列方法和贝叶斯模型将被用来区分信号和噪声，并识别原因变量之间的相互作用。生物能量学模型将为个体捕食者及其猎物提供食物网联系变化的定量估计，并为顶端营养协会的所有成员提供累积变化。一种新的模拟模型(Ecosim II)创建了整个生态系统的食物网背景，将用于探索对不断变化的死亡率、不同的生活史战略和在西北夏威夷群岛周围建立的栖息地避难所的作用的反应。最近保育人士对大型捕食性鱼类的关注上升是基于它们在维持远洋生态系统的生态完整性方面所扮演的未知角色。我们必须更好地了解这些迁徙捕食者的影响以及它们与目前和未来中上层鱼类避难所所包围的栖息地的相互作用。这种理解必须放在削弱或放大食物网效应的环境变化的背景下。

Exploitation of apex predators in pelagic food webs should result in a set of ecological changes at several scales. We will determine the dynamics of compensatory responses by apex predators (large tunas, billfishes and sharks) and some of their primary prey (squids, small tunas and juvenile mahimahi) in the pelagic food webs of the Central North Pacific (CNP). We will test for fishery-induced changes in growth rates, predator-prey interactions (diets), life history characteristics such as size or age at maturity, and species composition of the fish community. Analyses of food web dynamics will be used to evaluate the ecological consequences of changes in exploitation. We will use retrospective analyses of long-term data sets provided by collaboration with the Honolulu Laboratory, National Marine Fisheries Service. Responses to `pulse` manipulations will derive from analyses of recent evidence for major, rapid changes in exploitation effects, prey availability, and environmental effects (oceanic regime shifts). Responses to `press` manipulations of apex predator populations will derive from the 35-50 year records of basic biological data, life history studies and catch data maintained by NMFS. Contemporary data on growth rates, diets, life history characteristics, and species composition will be compared with those collected since 1948. This effort will employ three classes of analytical tools. Time-series methods and Bayesian models will be used to discern signal from noise and to identify the interactions of causative variables. Bioenergetics models will provide quantitative estimates of the changes in food web linkages for individual predators, their prey and the cumulative change for all members of the apex trophic guild. A new simulation model (Ecosim II) creates the food web context of an entire ecosystem and will be used to explore responses to changing mortality rates, different life history strategies and the role of a habitat refuge created around the Northwest Hawaiian Islands. The recent rise of conservationist concern for large predatory fishes is based on their unknown role in sustaining the ecological integrity of pelagic ecosystems. It is imperative that we better understand the effects of these migratory predators and their interactions with habitats encompassed by current and future refuges for pelagic fishes. That understanding must be set in the context of environmental changes that dampen or amplify food web effects.