The effect of turbulent strain rate on sturgeon larvae in fishways

Lake sturgeon (Acipenser fulvescens) have recently been a target for conservation in the Laurentian Great Lakes. While improving spawning success has been a major goal of these efforts, an often-overlooked component is the survival of the larvae after hatching, during the period of downstream drift. In a dammed river system, during this phase, they may need to drift past dam infrastructure. This journey past dams often results in an increase in larval mortality for a variety of reasons, including exposure to highly turbulent flow. Quantifying the aspects of turbulence related to larval mortality will inform retrofitting or future design efforts of fishways to improve larval viability. This project uses dimensional arguments to characterize the flow conditions influencing larvae viability through fishways. Following Kolmogorov’s theory (1941), ??=ηRe^-3/4, where ?? is the smallest eddy diameter and η is the smallest fishway pool dimension. The strain present in the fishway at the pertinent scale for sturgeon larvae, S, can be estimated using the water’s kinematic viscosity, v, the fishway’s Reynolds number, Re, and the smallest pool dimension as S=vRe^3/2/η². This analysis is then illustrated in the case of the Legendre-Vianney Fishway in Quebec.