A spatially resolved ecosystem model for the assessment of fisheries

以北纬47 ~ 62度，东经-12 ~ 10度的北欧陆架为研究区域，构建了以商业捕捞鱼类为研究对象的空间多物种生态系统模型。模型中的物种或功能群将被放置在生物细节的层次结构中。在最高或“结构化”的详细水平上，目标物种将通过相互作用的长度结构种群来表示，其中控制个体生长、捕食、繁殖和死亡的过程得到充分规定。在中间水平将是“非结构化”的生态系统元素，如底栖无脊椎动物和浮游动物，它们是动态表示的，但没有生活史细节。在最低层次的细节上，我们将有顶级捕食者（鲸类和海鸟）和捕鱼死亡率的“驱动因素”，它们没有被建模，但对生态系统的其余部分提供了强制功能。该模型将在不同的空间尺度上运行，从一系列相互关联的区域模型到覆盖整个域的中等尺度网格。物理环境将从海洋环流模型中获得，温度用于驱动依赖温度的过程，如生长率，流量决定浮游生物、浮游动物和鱼类幼虫的运输。该模型将使用渔业调查数据、浮游动物和底栖生物产量的估计以及顶级捕食者的消耗估计来进行参数化。由于顶级捕食者可能对生态和商业产生重要影响，一项联合提案（针对捆绑学生）将致力于对这些驱动因素进行改进的空间估计。自由参数将由马尔可夫链蒙特卡罗（MCMC）方法估计。我们将借鉴斯特拉斯克莱德大学开发的一系列计算创新，用于处理具有生活史结构和生长变异性的种群的明确空间模型。我们将使用Ecopath软件作为辅助工具来构建我们系统中物种之间传质的区域预算，然后将其与我们的模型预测的结果进行比较。我们的建模方法与其他生态系统建模方法有很大不同，例如Ecopath with Ecosim (EwE)，后者经常被提倡作为基于生态系统的渔业管理的前进方向。因此，我们建议的一个关键部分是进行涉及EwE区域生态系统模型的比较研究，以确定替代方法的优缺点。

We aim to construct a spatial multi-species ecosystem model focused on commercially exploited fish in the northern European shelf (47 to 62 degrees N, and -12 to 10 degrees E). Species or functional groups within the model will be placed within a hierarchy of biological detail. At the highest, or 'structured', level of detail the target species will be represented by interacting length-structured populations in which the processes governing individual growth, predation, reproduction, and mortality are fully specified. At an intermediate level will be 'unstructured' ecosystem elements, such as benthic invertebrates and zooplankton, that are represented dynamically but without life history detail. At the lowest level of detail we will have the 'drivers' of top predators (cetacean and seabird) and fishing mortality, which are not modelled but provide forcing functions to the rest of the ecosystem. The model will be run at various spatial scales, from a series of linked regional models through to medium-scale grid covering the entire domain. The physical environment will be obtained from an ocean circulation model, with temperatures used to drive temperature-dependent process such as growth rate, and flows determining the transport of plankton zooplankton and fish larvae. The model will be parameterised using fishing survey data, and estimates of zooplankton and benthic production, and estimates of consumption by top predators. Due to the potential for ecologically and commercially important impacts by top predators a joint proposal (for a tied studentship) will aim to produce improved spatial estimates for these drivers. Free parameters will be estimated by Markov chain Monte Carlo (MCMC) methods. We will draw on a range of computational innovations developed at Strathclyde University for dealing with explicitly spatial models of populations with life history structure and growth variability. We will use the Ecopath software as an aid to constructing regional budgets for mass transfer between the species in our system, and which can then be compared to those predicted by our model. Our modelling approach differs substantially from alternative ecosystem modelling methods, such as Ecopath with Ecosim (EwE), that are frequently advocated as the way forward for ecosystem-based management in fisheries. A key part of our proposal is therefore a comparative study involving EwE regional ecosystem models, with a view to identifying the strengths and weaknesses of alternative methodologies.