Effects of turbulence-inducing baffles on passage performance of brook trout, white sucker, and sea lamprey: implications for conservation and control

Invasive sea lamprey (Petromyzon marinus) control in the Great Lakes is ongoing. Installing passive selective passage structures could reduce costs, yet there is a need to evaluate such methods under realistic hydraulic conditions to inform designs. In this study, we evaluated the swimming performance of brook trout (Salvelinus fontinalis), white sucker (Catostomus commersonii), and sea lamprey under manipulated flows and baffle configurations in a 35 m flume lined with substrate preventing attachment. Using accelerated failure time models, we examined ascent distance (Dmax) under two slopes (1% and 3%) and velocities from 0.25–3.0 m s⁻¹. Responses varied by species: white sucker had the greatest Dmax, especially at 1% slope, whereas sea lamprey, despite lacking paired fins/rays, occasionally exceeded white sucker at 3% with small spoiler baffles and bare substrate. Contrary to common perception, brook trout, the only salmonid in this study, performed less well than the other two species. Across species, higher velocities impaired performance, with declines linked to energy dissipation (EDF). Findings show how hydraulic structures shape species-specific passage.