Collaborative Proposal: CAMEO: Using interdecadal comparisons to understand trade-offs between abundance and condition in fishery ecosystems

调查人员将对缅因湾一个生产性远洋生态系统的动态进行基于模型的调查。高生产力海洋生态系统的中等营养水平通常由少数几种中上层鱼类主导，如上升流环境中的沙丁鱼和凤尾鱼，或温带和亚极区的鲱鱼和/或海豚。这些物种是将能量输送到更高营养水平的重要通道，包括较大的鱼、海鸟和鲸目动物。当数量丰富时，小型中上层动物可以对猎物--通常是大型中游动物--施加巨大压力。小型中上层鱼类表现出复杂的动态，在生态系统方法下管理这些物种具有挑战性。这项模型研究将跟踪具有代表性的桡足类(Calanus finmarchicus，Centroages ypicus)、鲱鱼和蓝鳍金枪鱼的丰度和状况。研究人员将对20世纪80年代和90年代的情况进行严格比较，以开发该模型。他们将研究这一生态系统对中等营养层捕捞压力变化的敏感性，以及对初级生产量和时间变化的敏感性。他们还将考虑气温升高对Finmarchicus积累脂肪和改变鲱鱼和金枪鱼状况的能力的影响。该项目将导致对具有生产性食物网的生态系统的更好了解。它还将直接影响与缅因湾鲱鱼资源管理有关的问题。调查人员将审查忽视浮游动物和鱼类状况的后果，就像目前的种群评估一样。他们还将探索模型生态系统的动力学特性，并考虑在什么条件下可能同时拥有丰富和条件良好的鲱鱼。

The investigators will conduct a model-based investigation of the dynamics of a productive pelagic ecosystems in the Gulf of Maine. The middle trophic levels in highly productive marine ecosystems are typically dominated by a few species of pelagic fish, such as sardines and anchovies in upwelling environments or herring and/or capelin in temperate and subpolar regions. These species act as important conduits for energy to higher trophic levels, including larger fish, seabirds, and cetaceans. When abundant, small pelagics can exert significant pressure on their prey, typically large mesozooplankton. Small pelagic fish exhibit complex dynamics and managing these species under an ecosystem approach is challenging. This modeling study will track both the abundance and condition of representative copepods (Calanus finmarchicus, Centropages typicus), herring, and bluefin tuna. The investigators will use a rigorous comparison of conditions from the 1980s and 1990s to develop the model. They will examine the sensitivity of this ecosystem to changes in fishing pressure on the middle trophic levels and to changes in the magnitude and timing of primary production. They will also consider the impact of increased temperature on the ability of C. finmarchicus to accumulate lipids and alter the condition of herring and tuna.The project will lead to improved knowledge of ecosystems with productive food webs. It will also directly impact address issues related to the management of the herring resource in the Gulf of Maine. The investigators will examine the consequences of ignoring condition of zooplankton and fish, as is the case with the current stock assessment. They will also explore the dynamical properties of the model ecosystem and consider under what conditions it is possible to have both abundant and well conditioned herring.