From genes to ecosystems: an eco-evolutionary assessment of alternative harvesting strategies and consequences for fisheries productivity

我们将采用一种新颖的多学科方法来评估普通捕捞方法产生的生态进化变化对渔业生产力的影响程度。我们将融合种群基因组学、生态进化动力学和群落生态学的新兴理论、概念和新进展，在一系列封闭的天然鳟鱼种群中进行基于实验控制消耗的大规模收获选择实验。我们的项目将利用加拿大公园管理局的授权，积极恢复以前没有鱼的高山湖泊，这些湖泊在80-100年前引入了非本地鳟鱼。因此，它提供了一个特殊的机会，对社会经济上重要的鱼类种群（鲑科）的自然种群进行重复消耗，无论如何它们都会被移除。这些消耗将用于(i)探索关于大小选择性捕捞对渔业生产力和生态系统功能的影响的几个未经检验的假设，以及（ii）描述大幅度减少大小选择性捕捞的替代捕捞方法（“平衡捕捞”）的功效。同时，该项目将为加拿大最重要的遗产象征之一——壮丽的落基山脉湖泊——使用非毒性清除技术实现生态系统恢复目标做出贡献。鳟鱼枯竭将模拟(i)通常发生的大型个体的尺寸选择性捕捞（4个湖泊）和（ii）“平衡捕捞”，其中死亡率分布在生态系统中最广泛的尺寸范围内，与其自然生产力成比例，目的是将尺寸选择性和相关的进化变化降至最低（4个湖泊）；另外4个未枯竭的湖泊将作为控制。自2011年以来，在第13个湖泊进行了密集的大小选择性收获，并提供了与收获选择性相关的基因组变化的长期时间评估。湖泊将具有类似的特征，并且在鳟鱼枯竭之前具有可忽略不计的捕捞历史。将连续数年对多个年龄组进行基因、人口、群落和生态系统各级的一系列反应变量/指标的耗竭前后监测。

We will employ a novel, multidisciplinary approach to assess to what degree eco-evolutionary changes generated by common harvesting approaches affect fisheries productivity. We will blend emerging theory, concepts and new advances in population genomics, eco-evolutionary dynamics and community ecology to conduct a large scale harvest selection experiment based on experimentally-controlled depletions across a series of closed, natural trout populations. Our project will take advantage of the mandate of Parks Canada to actively restore previously fishless alpine lakes where non-native trout were introduced 80-100 years ago. Hence it provides an exceptional opportunity to conduct replicated depletion of natural populations of a socio-economically important fish species groups (salmonids) where they will be removed anyways. These depletions will be used to (i) explore several untested hypotheses about the effects of size-selective harvesting on fisheries productivity and ecosystem function and (ii) characterize the efficacy of an alternative harvesting approach to substantially reduce size-selective effects ('balanced harvesting'). Concurrently, the project will contribute to reaching ecosystem restoration targets using non-poison removal techniques, for one of Canada's most important heritage symbols - the magnificent Rocky Mountain lakes. Trout depletion will simulate (i) commonly occurring size-selective harvesting of large-sized individuals (4 lakes) and (ii) 'balanced harvesting', wherein mortality is distributed across the widest range of sizes in an ecosystem, in proportion to their natural productivity, with the aim that size-selectivity and associated evolutionary changes are minimized (4 lakes); 4 additional, non-depleted lakes will act as controls. Intense size-selective harvesting has taken place in a 13th lake since 2011 and affords a longer-term temporal assessment of genomic change associated with harvesting selectivity. Lakes will be of a similar characteristics and have had a negligible history of fishing prior to trout depletion. Pre- and post-depletion monitoring of a series of response variables/metrics at the gene, population, community and ecosystem levels will be conducted on multiple age-cohorts over successive years.