Predicting fish production from lake size using novel measurement strategies of fish behavior

淡水鱼对加拿大人来说是一种特别重要的资源。令人不安的是，最近的研究表明，一些休闲渔业正在遭受隐藏的崩溃；鱼类产量(即每一区域每年产生的新组织数量)正在下降，而产量(公斤年产量-1)保持不变，导致过度捕捞。由于产量下降和过度捕捞而关闭的渔业对加拿大人和土著人民以及整个全球社会构成巨大的经济和文化威胁。然而，目前加拿大内陆湖泊的鱼类产量是否在下降仍是个未知数。影响鱼类栖息地的全球变暖也仍然是未来鱼类生产和可持续收获的一个隐约可见的不确定性。渔业管理者面临的一个主要知识缺口是，鱼类栖息地的使用和产量如何随着时间的推移(季节性和年际变化)以及从小湖泊到大湖泊发生可预测的变化。4所大学与安大略省自然资源和林业部(OMNRF)之间的合作将通过使用一个易于测量的变量湖泊大小来预测鱼类栖息地的使用和产量来解决这一知识差距。为此，我们将使用声学遥测和稳定同位素，生成关于鱼类栖息地使用(即在湖中的位置)和饮食的高分辨率数据，其中包括3个共同出现的具有娱乐和文化价值的物种：湖泊鲑鱼(Salvelinus Namaycush)、思科(Coregonus Artedi)和小口鱼(Micropterus Dolomieu)。我们的新方法将首次量化在一个小型、中型和大型湖泊中的三个物种在所有季节和五年中的栖息地和饮食重叠。这一结果将为渔业管理者提供前所未有的能力，根据易于测量的湖泊特征来预测鱼类栖息地的使用和产量。我们的发现将从根本上阐明季节性变化的重要性，包括研究较少的冬季，在构建物种相互作用和塑造湖泊大小梯度上的鱼类行为方面。结果将导致新的渔业管理方法和政策，这些方法和政策将在加拿大范围内广泛应用，以帮助保护未来的淡水鱼，使所有加拿大人受益。

Freshwater fish are an exceptionally important resource to Canadians. Disturbingly, recent research demonstrates some recreational fisheries are suffering from hidden collapses; fish production (i.e. the amount of new tissue generated per area per year) is declining while harvest (kg yr-1) remained constant, leading to overharvest. Fisheries closure due to declining production and overharvest is an enormous economic and cultural threat to Canadians and indigenous peoples, and to global society as a whole. Currently, however, whether fish production is declining across Canada's inland lakes remains unknown. Warming global temperatures that affect fish habitat also remain a looming uncertainty for fish production and sustainable harvest into the future. A major knowledge gap facing fisheries managers is how fish habitat use and production change predictably through time (seasonally and interannually) and from small to large lakes. The partnership between 4 Universities and the Ontario Ministry of Natural Resources and Forestry (OMNRF) will address this knowledge gap by using an easily measured variable, lake size, to predict fish habitat use and production. To do so, we will generate highly resolved data on fish habitat use (i.e. position in the lake) and diet, using acoustic telemetry and stable isotopes, in 3 co-occuring species of recreational and cultural value: lake trout (Salvelinus namaycush), cisco (Coregonus artedi), and smallmouth bass (Micropterus dolomieu). Our novel approach will, for the first time, quantify habitat and diet overlap among 3 species throughout all seasons and across 5 years in a small, intermediate and large-sized lake, simultaneously. The results will provide fisheries managers with an unprecedented ability to predict fish habitat use and production from easily measured lake characteristics. Our findings will shed fundamental new light on the importance of seasonal variation, including poorly studied winter periods, in structuring species interactions and shaping fish behavior across a lake size gradient. The results will lead to new fisheries management methods and policies that will be applied broadly Canada-wide to benefit all Canadians by helping protect freshwater fishes into the future.