Population dynamics in fishes: recruitment processes, environmental variation, adaptation and harvest

无论是跨水体还是在单一水体内进行比较，鱼类种群的丰富度都是高度不同的。我的研究计划的目标是了解环境特征和收获在多大程度上控制这些可变种群。这种变化似乎大部分源于鱼类在其生命的第一年的生长和存活的变化。因此，我正在研究幼鱼的行为和生理如何在生长、能量储存和存活方面影响它们早期的成功。幼鱼面临许多挑战，因为它们很容易受到捕食者的攻击，如果它们没有储存足够的能量来在几乎没有猎物可用的时期生存下来，它们就很容易在第一个冬天挨饿。我研究了幼鱼如何在捕食时间上进行权衡，这使它们容易受到捕食者的影响，并受到冬季生存所需能量储存的限制。通过对比鱼类在不同环境中如何进行这种权衡，我们正在了解这些过程对生存的重要性，以及鱼类适应其栖息地环境的重要性。此外，我们感兴趣的是鱼类种群对捕捞的适应能力如何，以及当我们过度捕捞鱼类种群时，幼鱼产量如何减少。我们对这项工作的一般方法是使用野外实验、观察和模型相结合的方法来评估环境变异性和捕捞对鱼类种群生存的贡献。在环境条件不同的湖泊中进行的实验，我们可以在其中操纵猎物和捕食者的密度和捕获率，提供了必要的对比，以评估这些因素对鱼类种群变异性的贡献。这项基础生物学研究对气候变化和收获对鱼类长期可持续性的影响等问题具有重要影响。

The abundance of fish populations is highly variable, whether comparing across water bodies or within a single water body over time. The goal of my research program is to understand the degree to which environmental characteristics and harvest control these variable populations. It appears as if the majority of this variability originates from variation in fish growth and survival during their first year of life. I am therefore studying how the behaviour and physiology of young fish impacts their early success in terms of growth, energy storage and survival. Young fish face many challenges in that they are very susceptible to predators and to starvation during their first winter if they have not stored sufficient energy to survive a period with little prey available. I study how young fish trade-off time spent foraging, which makes them susceptible to predators, with the energetic constraints of sufficient energy storage for winter survival. By contrasting how fish make this trade-off in different environments we are learning the importance of these processes to survival and of adaptation of fish to their home environments. In addition we are interested how resilient fish populations are to harvesting and how the production of young fish is curtailed as we overharvest fish populations. Our general approach to this work is to use a combination of field experiments, observations and models to assess the contribution of environmental variability and harvest to fish population viability. Experiments in lakes which vary in environmental conditions and within which we can manipulate prey and predator density and harvest rate provide the contrasts necessary to assess the contribution of these factors to fish population variability. This fundamental biological research has important implications to issues such as impacts of climate change and harvest on the long-term sustainability of fishes.