Uncertainties of population resilience and recovery: linking life histories to ecosystems

了解种群对干扰的恢复能力及其在枯竭后的恢复能力是理论种群生物学及其在保护生物学和可持续收获策略发展中的应用的基础。海洋渔业是自然种群中人类造成死亡的一个主要规模系统。在过去的几十年里，许多商业捕捞的种群数量已经下降到历史最低水平，尽管捕捞压力大大减少，但许多种群几乎没有恢复的迹象。近年来，随着许多商业捕捞鱼类种群的年龄和成熟尺寸下降以及体型变小的趋势，生活史在鱼类种群恢复能力及其人口统计学特性中的作用得到了相当大的关注。鱼类生活史的变化可以直接改变种群增长率，但它们也可能通过生态系统水平的反馈影响种群恢复能力，形成任何基于单一物种的种群恢复力和恢复能力预测的主要不确定性成分。虽然人口预测可以通过更严格地结合关键驱动因素和生态系统的观点来改进，但自然界始终存在随机性，因此感兴趣的过程的结果总是在某种程度上是随机的。本文研究了鱼类种群对过度捕捞的恢复力和恢复力的驱动因素和不确定性。为此，我将计划生活史变化对种群动态的生态系统反馈，并估计与鱼类种群动态相关的固有不确定性。为此，我将在异速营养网络建模框架中建立基本的生活史不变量，并分析加拿大渔业背景下鱼类种群动态的经验时间序列。拟议的研究旨在为影响自然种群和人类种群恢复速度和不确定性的因素提供新的见解。这将通过(i)考虑个人和生态系统的观点，（ii）量化恢复能力的内在不确定性，以及（iii）将这种不确定性纳入不断变化的环境中枯竭人口的重建计划。这项工作直接适用于自然和受人类影响的物种，以及它们的保护和可持续管理。*********

Understanding the resilience of populations to disturbance and their ability to recover following depletion is fundamental to both theoretical population biology and its applications to conservation biology and the development of sustainable harvesting strategies. Marine fisheries represent a major scale system of human-induced mortality in natural populations. Over the past decades, numerous commercially fished populations have declined to historically low levels and many show little signs of recovery despite large reductions in fishing pressure. The role of life-histories in fish population recovery ability and its demographic properties has gained considerable attention recently, as trends towards lower age and size at maturity and smaller body sizes have been documented in many commercially exploited fish populations. Changes in fish life histories can alter population growth rate directly, but they might also affect population recovery ability through ecosystem-level feedbacks, forming a major uncertainty component about any single-species based projections about population resilience and recovery ability. While population projections can be improved by more rigorous incorporation of key drivers and an ecosystem perspective, stochasticity is always present in nature, such that an outcome of the process of interest always remains to some extent random. The present proposal investigates the drivers and uncertainty of fish population resilience to and recovery from overfishing. To this end, I will project ecosystem feedbacks of life-history changes on population dynamics and estimate inherent uncertainty associated with fish population dynamics. To these ends, I will build fundamental life-history invariants into the Allometric Trophic Network modelling framework and analyze empirical time series on fish population dynamics in the context of Canadian fisheries. The proposed research aims to provide new insights into the factors that affect the rate and uncertainty of recovery in natural and human-harvested populations. This will be done by (i) accounting for both individual and ecosystem perspectives, (ii) quantifying the inherent uncertainty in recovery ability, and (iii) incorporating this uncertainty in rebuilding plans for depleted populations in a changing environment. The work has direct applicability to both natural and human-affected species, to their conservation and sustainable management.*********