The role of turbulence on the early life history and recruitment of Walleye in Lake Erie

了解商业和经济上重要的鱼类物种的招募对加拿大的管理和可持续发展至关重要。伊利湖的瓦利耶鱼就是这种情况，它每年为加拿大和美国提供数十亿美元的渔业收入。存在多个产卵地点，每个地点的质量和对鱼幼虫生产的贡献不同。在最初的3-4个月里，由于泉水温度和湍流运动的影响，幼虫的生长/存活存在不确定性。在正确的时间找到合适的栖息地（即理想的水温和丰富的浮游动物猎物）可以解释招募模式（即匹配/不匹配假设1：幼虫运输）。此外，近床湍流（即床剪切应力）对卵向软沉积物移动的影响（在软沉积物中它们窒息），卵和幼虫在水柱和湖盆中的命运和运输，以及水柱湍流对幼虫摄食的影响可能很重要，但尚不清楚。来自海洋系统的见解表明，低水平的湍流通过增加与猎物的接触来增强鱼类幼虫的摄食，但高水平的湍流干扰捕获机制，导致猎物捕获减少。一旦到达苗圃，高水柱湍流可能会导致第二次匹配/不匹配（即匹配/不匹配假设2：幼虫摄食），从而降低鳉鱼幼虫的存活和生长。因此，我们建议使用实验室实验和耦合的三维湖泊水动力-生态模型来确定：(i)湍流如何影响白眼鱼卵的孵化/迁移和幼虫的生长；（ii）湍流影响何时/何地发生；（iii）不同产卵地点的相对贡献；（iv）使用生物物理粒子跟踪模型（即基于个体的模型）来确定幼鱼如何从产卵地点移动到苗期地点。该生物物理建模系统将用于预测伊利湖瓦利眼鱼产卵和育苗地点的条件，这对安大略省自然资源和林业部对这一重要渔业的管理至关重要，因此对加拿大有很大的好处。

Understanding the recruitment of commercially and economically important fish species is critical to their management and sustainability in Canada. This is the case for Walleye in Lake Erie, which support an annual multi-billion-dollar fishery for Canada and the USA. Multiple spawning sites exist, each differing in quality and contribution to the production of fish larvae. Uncertainties exist about larval growth/survival during their first 3-4 months when spring water temperature and turbulent water motions affect recruitment. Locating suitable habitat at the correct time (i.e., ideal water temperatures and abundant zooplankton prey) may explain patterns in recruitment (i.e., match/mismatch hypothesis 1: larval transport). Moreover, the effects of near-bed turbulence (i.e., bed shear stress) on egg dislodgement to soft sediments where they suffocate, the fate and transport of eggs and larvae through the water column and lake basin, and the effects of water-column turbulence on larval feeding may be important but are yet unknown. Insights from marine systems indicate that low levels of turbulence enhance feeding by fish larvae by increasing encounters with prey, but high turbulence interferes with capture mechanisms leading to lower prey capture. Walleye larval survival and growth could be reduced by high water column turbulence once they reach their nursery locations causing a second match/mismatch (i.e., match/mismatch hypothesis 2: larval feeding). We propose, therefore, to determine: (i) how Walleye egg hatching /dislodgement and larval growth are affected by turbulence using laboratory experiments and coupled three-dimensional lake hydrodynamic-ecological models, (ii) when/where these turbulence effects occur, (iii) the relative contributions of the various spawning sites, and (iv) how larval fish move from spawning sites to nursery sites using a biophysical particle tracking model (i.e., individual-based model). This biophysical modelling system will be developed to predict the conditions at Walleye spawning and nursery locations in Lake Erie, which is critical to the Ontario Ministry of Natural Resources and Forestry's management of this important fishery, and thus of great benefit to Canada.