Modeling interactions between top predators and fishing vessels: implications for fisheries management in a wider ecosystem

在2002年约翰内斯堡可持续发展问题世界首脑会议(WSSD)上，签署国同意到2012年制定和实施渔业生态系统办法(EAF)。EAF的一个中心原则是，管理优先事项应从生态系统而不是目标物种开始，必须将人类视为正在管理的生态系统的组成部分。然而，实施EAF会带来一系列所谓的邪恶问题，因为很难找到对生态系统所有组成部分都公平的解决方案。然而，如果能够开发一个共同的框架，在该框架内可以评估和比较系统所有组件的风险，则解决方案是可能的。该项目将通过开发一个空间上明确的数学和统计模型来促进这一框架，该模型描述了在北海开发具有重要商业价值的鱼类资源的“捕食者”(灰海豹、海豹和不同的捕捞船队)之间的相互作用。这个模型将被用来调查不同的管理方案对个体捕食者和生态系统的影响。我们尤其会集中研究拟议的海洋条例草案白皮书所概述的海洋环境管理改革所带来的影响。我们将使用操作模型方法来描述三组不同的过程：底层生物系统的运行方式；该系统的管理方式；以及从该系统收集和分析数据的方式。我们将推广这一方法，通过应用计算机密集的统计方法，使数据与渔业上岸和海豹状况及数量的数据相吻合，从而对潜在的生物和经济过程提供更多的洞察。由于运营模型可以清楚地考虑到我们对系统的了解中的主要不确定性来源，因此它们对于评估与不同管理方案相关的风险特别有用。运营模式将分两个阶段开发。一组功能反应将被用来预测鳕鱼、黑线鳕、鳕鱼和鲱鱼的消费/捕获量与它们在特定空间位置的丰度之间的关系。一组综合反应将被用来预测捕捞努力的分布和海豹在太空中的觅食。捕食者的觅食策略和收集其行为信息的方式之间的相似之处将促进建模过程。它们都从猎物中获得了相对明确的净收益，这些净收益是由它们捕获的东西的价值和获得它的成本之间的平衡决定的。我们将侧重于捕食者的一个子集，它们的觅食受到限制，因为需要定期返回到相对较少的明确界定的地点进行捕捞和繁殖，对于海豹来说，或者对于渔业来说，是上岸捕捞和补充燃料。我们将在以捕鱼/觅食旅行为基本时间单位的共同经济框架中评估它们的收益和成本。我们将根据海洋哺乳动物研究组收集的大量海豹活动数据，以及根据欧盟委员会的MAFCONS项目收集的北海捕捞活动的大量数据库，建立这些模型。我们将把这些组合模型与北海主要繁殖群体的渔业上岸数据和海豹身体状况数据进行匹配。最后，我们将模拟实施Defra提出的新的海洋资源管理制度的方式，例如一系列保护区和更多地强调区域管理。然后，我们将使用情景分析来预测这些制度对捕鱼船队和捕食者的空间分布、对它们的上岸和身体状况以及对它们的猎物资源的可能影响。

At the 2002 World Summit on Sustainable Development (WSSD) in Johannesburg, signatory nations agreed to develop and implement an ecosystem approach to fisheries (EAF) by 2012. A central tenet of EAF is that management priorities should start with the ecosystem rather than the target species, and that humans must be considered as an integral part of the ecosystems that are being managed. However, implementing an EAF poses a range of so-called wicked problems, because it is difficult to find a solution that is equitable for all components of the ecosystem. A solution may, however, be possible if a common framework can be developed within which the risks to all components of the system can be evaluated and compared. This project will contribute to that framework by developing a spatially-explicit mathematical and statistical model of the interactions between the 'predators' (grey and harbour seals, and different fishing fleets) that exploit commercially-important fish stocks in the North Sea. This model will be used to investigate the impacts of different management options on the individual predators and on the ecosystem. In particular, we will focus on the implications of changes in the management of the marine environment that are outlined in the White Paper on the proposed Marine Bill. We will use an operating model approach that describes three different sets of processes: the way in which the underlying biological system operates; the way in which this system is managed; and the way in which data from the system are collected and analysed. We will extend this approach to provide additional insight into the underlying biological and economic processes by applying computer-intensive statistical methods to fit the to data on fisheries landings and seal condition and numbers. Because operating models can take explicit account of the major sources of uncertainty in our knowledge of the system, they are therefore particularly useful for evaluating the risks associated with different management scenarios. The operating model will be developed in two phases. A set of functional responses will be used to predict the relationship between the consumption/catch of cod, haddock, whiting and herring and their abundance at a particular spatial location. A set of aggregative responses will be used to predict the distribution of fishing effort and seal foraging over space. The modelling process will be facilitated by similarities between the foraging strategies of the predators and the ways in which information on their behaviour is collected. They all derive relatively well-defined net benefits from their prey that are determined by the balance between the value of what they catch and the cost of obtaining it. We will focus on a subset of the predators whose foraging is constrained by the need to return at regular intervals to a relatively small number of well-defined locations to haul out and breed, in the case of seals, or to land their catch and refuel, in the case of the fisheries. We will evaluate their benefits and costs in a common economic framework that uses the fishing/foraging trip as the basic time unit. We will base these models on the large body of data on seal movements collected by the Sea Mammal Research Unit, and the extensive database on fishing effort in the North Sea collected under the European Commission's MAFCONS project. We will fit these combined models to data on fisheries landings and data on the body condition of seals at the major breeding colony in the North Sea. Finally, we will model the way in which new management regimes for marine resources, such as a range of protected areas and a greater emphasis on regional management, proposed by Defra are likely to be implemented. We will then use scenario analysis to predict the likely impacts of these regimes on the spatial distribution of fishing fleets and predators, on their landings and body condition, and on their prey resources.