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

我们将采用一种新的、多学科的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，在一系列封闭的自然鲑鱼种群中进行大规模的收获选择实验，该实验基于实验控制的耗竭。我们的项目将利用加拿大公园的授权，积极恢复以前没有鱼的高山湖泊，那里在80-100年前引入了非本地鲑鱼。因此，它提供了一个特殊的机会，可以对具有社会经济意义的重要鱼类种群(鲑鱼)的自然种群进行重复枯竭，在那里无论如何都会将其清除。这些消耗将被用来(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)表征显著减少大小选择性影响的替代捕捞方法(“平衡捕捞”)的有效性。同时，该项目将有助于实现加拿大最重要的遗产标志之一-壮丽的落基山脉湖泊-使用非有毒物质清除技术的生态系统恢复目标。鲑鱼枯竭将模拟(I)经常发生的对大型个体(4个湖泊)的大小选择性捕捞和(Ii)“平衡收获”，其中死亡率分布在生态系统中最广泛的大小范围内，与它们的自然生产力成比例，目的是最大限度地减少大小选择性和相关的进化变化(4个湖泊)；另外4个未枯竭的湖泊将作为对照。自2011年以来，在第13个湖泊进行了密集的大小选择性捕捞，为与捕捞选择性相关的基因组变化提供了较长期的时间评估。湖泊将具有类似的特征，在鲑鱼枯竭之前的捕鱼历史可以忽略不计。在基因、种群、社区和生态系统各级对一系列反应变量/指标的耗竭前和耗竭后的监测将在连续几年对多个年龄段进行。

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.