Upriver migrating sea lamprey exhibit similar responses to hydrodynamic features as other up and downriver-moving species

James R Kerr ^1* Daniel P Zielinski ² Christopher M Holbrook ³ Richard A Goodwin ⁴ Robert L McLaughlin ¹

• ¹ University of Guelph, Guelph, Canada
• ² Great Lakes Fishery Commission, Ann Arbor, Michigan, United States
• ³ Hammond Bay Biological Station, Great Lakes Science Center, United States Geological Survey, Millersburg, Michigan, United States
• ⁴ Environment Laboratory, U.S. Army Engineer Research and Development Center, Portland, United States

Identifying commonalities in how fish navigate rivers near infrastructure will enhance water operations and design by improving our ability to predict engineering outcomes (e.g. barrier construction/removal, fish passage installation) in novel settings before the cost of real-world implementation. Evidence from intermediate-scale computer models (time scales of minutes to days and spatial scales less than 2 km) suggests that fish movement behaviour in rivers is frequently governed by responses to one or more of the following hydrodynamic features: (1) flow direction (i.e., rheotaxis), (2) flow velocity magnitude, (3) turbulence, and (4) depth, plus (5) the integration of information over recent time periods (i.e., memory/experience).However, the lack of consistent modelling approaches, infrequent assessment of each response in isolation and combination, and a focus on a limited number of species means the generality of these responses is uncertain. We use a computer model to apply responses to the four hydrodynamic features plus memory/experience in different combinations to study their value for reproducing the movement of an infrequently modelled species and lifestage, upriver migrating adult sea lamprey, Petromyzon marinus, near infrastructure. Our analysis indicates that rheotaxis and a response to velocity magnitude as well as recent past experience improve lamprey prediction compared to other, simpler forms of modelled behaviour. Sea lamprey movement is also biased toward lower levels of turbulence (e.g., turbulent kinetic energy) or its precursor (i.e., the spatial gradient in water speed). A response to water depth was not found to be important, but the modelled domain was two-dimensional which limited our assessment. As similar responses to hydrodynamic features are found in very different fish, commonalities appear to underlie river navigation across a range of species and life stages that share the goal-oriented behaviour of upriver and downriver movement. The systematic approach of our analysis highlights the accuracy trade-offs of each response, individually and in combination, that often accompany alternative behavioural formulations in a computer model of fish movement. The model structure provides a framework to which future findings from the analyses of additional species in different contexts can be added.