Population structuring of Cod around the UK; scale, mechanism and dynamics

许多全球海洋渔业已经崩溃，或处于创纪录的丰度水平。持续的捕捞和气候变化的不确定影响增加了对鱼类资源的进一步压力。因此，需要新的战略来协助我们的管理和保护工作。其中一项发展将是将鱼类种群之间存在的空间相关生物差异的程度和动态纳入种群评估。这种信息很重要，因为大多数被开发的鱼种由不同的个体组成，它们的生长、繁殖、迁徙趋势和死亡率都不同。因此，例如，将捕捞强度水平与捕捞后预计的补给率相匹配就变得可取了，从而降低了个别种群灭绝的可能性。保护种群之间的这种生物差异对于维持野生鱼类种群的遗传多样性也很重要，因此赋予它们更大的进化潜力来适应环境的变化。这项工作的一个关键组成部分是检验与卵和幼虫扩散等因素的相对贡献有关的假设，以及幼体和成体在维持这种生物学差异方面的行为。通过将英国三大渔业机构(FRS、CEFAS、AFBI)的研究工作与英国大学的合作伙伴、一家NERC研究所和一名来自丹麦的国际鳕鱼专家整合在一起，我们将首次研究整个英国水域鳕鱼(Gadus Morhua)种群结构的范围、模式和稳定性。我们将使用现有的(微卫星)和新的(单核苷酸多态)遗传标记来评估来自不同产卵群体的个体杂交的程度，并将这些间接扩散方法与对耳骨(耳石)和被电子标记的个体进行化学分析所获得的鱼类运动的直接测量进行比较。然后，我们将把这些数据输入到定制的鳕鱼种群模型中，该模型将测试幼体阶段和成体扩散对观察到的种群分离模式的可能影响，并模拟基于空间的种群差异对捕捞努力、种群恢复和海洋保护区设计等方面的可能后果。这项提议将是英国大学和所有三个英国渔业机构首次合作解决这个问题，这个问题必须考虑到英国大片地区和邻近水域鱼类种群的相互依存关系。该提案将产生对种群分离的新的遗传估计，特别是在凯尔特海和爱尔兰海以及北海南部和英吉利海峡等不确定地区，并提供可用于预测持续捕捞压力和环境变化对鳕鱼种群的影响的新理论工具(种群模型)。此外，这些工具将提供关于海洋保护区的适当空间规模和分布的信息，以及现已正式濒危并列入世界自然保护联盟红色名录(http://www.iucnredlist.org/).)的物种的可能种群回收率

Many global marine fisheries have collapsed, or are at record low levels of abundance. Continuing exploitation and the uncertain impacts of climate change are adding further pressures on fish resources. New strategies are therefore required to assist in our management and conservation efforts. One such development will be to incorporate the extent and dynamics of spatially-associated biological differences that exist among fish stocks into stock assessment. Such information is important since most exploited fish species comprise assemblages of individuals that differ in their vital rates of growth, reproduction, migratory tendency and mortality. It therefore becomes desirable, for example, to match the level of fishing intensity to the projected rate of replenishment following harvesting, thereby reducing the probability that individual stocks will become extinct. Conserving such biological differences among stocks is also important in the maintenance of genetic diversity in wild fish populations, so endowing them with greater evolutionary potential for adapting to changes in the environment. A critical component of such work involves the testing of hypotheses relating to the relative contributions of such factors as dispersal of eggs and larvae, and behaviour of juveniles and adults in maintaining such biological differences. By integrating research efforts across each of the three major UK fisheries agencies (FRS, CEFAS, AFBI) with partners in UK Universities, a NERC Institute and an international cod expert from Denmark, we will for the first time examine the extent, patterns and stability of cod (Gadus morhua) population structuring throughout UK waters. We will employ existing (microsatellites) and new (single nucleotide polymorphisms) genetic markers to assess the extent to which individuals from different spawning groups interbreed, and will compare these indirect methods of dispersal with direct measure of fish movement taken from chemical analysis of ear-bones ('otoliths') and individuals that have been electronically 'tagged'. We will then input these data to tailored cod population models that will test the likely effects of young-stage and adult dispersal on observed patterns of stock separation, as well as simulating the likely consequences of spatially-based differences in stocks on such things as fishing effort, stock recovery and the design of marine protected areas. The proposal will represent the first opportunity for UK Universities and all three UK Fisheries agencies to work together on a problem that has to take account of the interdependence of fish stocks across large regions of UK and adjoining waters. The proposal will generate new genetic estimates of stock separation, especially in areas of uncertainty such as the Celtic and Irish Seas and the Southern North Sea and English Channel, as well as the provision of new theoretical tools (population models) than can be used to forecast the impact of continued fishing pressure and environmental change on cod populations. Moreover, the tools will provide information on the appropriate spatial scale and distribution of marine protected areas and the probable rates of stock recovery in a species that is now formally endangered and listed in the IUCN Red List (http://www.iucnredlist.org/).