Flow, force, behaviour: assessment of a prototype hydraulic barrier for invasive fish

Joschka Wiegleb,Georg Rauter,Frank Seidel,Patricia Burkhardt-Holm,Philipp E Hirsch

doi:10.1007/s10750-021-04762-z

Joschka Wiegleb, Georg Rauter + Show 3 more

Open Access

https://doi.org/10.1007/s10750-021-04762-z

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Abstract

Migration barriers being selective for invasive species could protect pristine upstream areas. We designed and tested a prototype protective barrier in a vertical slot fish pass. Based on the individuals’ swimming responses to the barrier flow field, we assumed this barrier would block the ascension of the invasive round goby, but allow comparable native species (gudgeon and bullhead) to ascend. The barrier was tested in three steps: flow description, quantification of forces experienced by preserved fish in the flow field, and tracking the swimming trajectories of ca. 43 live fish per trial and species. The flow and the forces were homogenous over the barrier, though gudgeon experienced significantly smaller forces than round goby or bullhead. The swimming trajectories were distinct enough to predict the fish species with a random forest machine learning approach (92.16% accuracy for gudgeon and 85.24% for round goby). The trajectories revealed round goby and gudgeon exhibited increased, but varied, swimming speeds and straighter paths at higher water discharge. These results suggest that passage of round goby was prevented at 130 L/s water discharge, whereas gudgeon and bullhead could pass the barrier. Our findings open a new avenue of research on hydraulic constructions for species conservation.

Highlights

The majority of the world’s rivers are fragmented by anthropogenic barriers (Belletti et al, 2020)
The flow measurements revealed a moderate correlation between flow velocity and turbulent kinetic energy (TKE) (r = 0.78, p \ 0.01; Fig. 4B) at 130 L/s water discharge, indicating that the small-scale hydraulic properties are not well represented in the mean velocities measured at the chosen points
We aimed to evaluate whether the hydrodynamic conditions within the barrier can selectively prevent the upstream migration of an invasive fish species

Summary

Introduction

The majority of the world’s rivers are fragmented by anthropogenic barriers (Belletti et al, 2020). Fish pass design increasingly needs to respond to the demands for protection of specific species (United Nations, 1992). A combination of research approaches from fluid dynamics, engineering and behavioural ecology is necessary to account for the individual differences in swimming performance between species (Kemp, 2012). This idea has been implemented in studies applying robotics to describe basic fish swimming kinematics (Thandiackal et al, 2021) or studies linking flow measurements with the swimming behaviour of fish (Drucker and Lauder, 1999; Sagnes and Statzner, 2009; Porreca et al, 2017). Subsequent studies have focused on fish pass hydraulics (Larinier, 2008; Tsikata et al, 2014; Baki et al, 2017) or species compositions and fish swimming behaviour in fish passes (Jansen et al, 1999; Aarestrup et al, 2003; Knaepkens et al, 2005)

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