Effects of fish size, time‐to‐fatigue and turbulence on swimming performance: a case study of Galaxias maculatus

Abstract

A simple relationship for the inanga Galaxias maculatus swimming velocity is suggested and tested in low and high turbulence channels. The relationship connects the swimming velocity with fish Reynolds and Froude numbers and can be used in both ecological analysis (e.g. habitat requirements) and management strategies (e.g. fishways design). Contrary to some previous studies and intuition, effects of turbulence on swimming performance appeared to be negligible. The most likely explanation for this result relates to mechanics of fish-turbulence interactions that may be dependent on both the turbulence scales and energy. The data suggest that future studies of turbulence effects on fish behaviour should involve, in addition to turbulence energetics, consideration of fish dimensions in relation to the spectrum of turbulence scales.

Fish swimming speed variability at constant flow:Galaxias maculatus

“…The empirical relationship of Nikora et al (2003) provided greater time-to-fatigue than observed in our experiments, predicting time-to-fatigue at velocities of 0.48 m s" 1 and 0.60 m s" 1 as 112 s and 40 s, respectively. The lower water temperature in our experiment (11.9-14° C) compared to that of Nikora et al (2003) (16-22°C) may have been a factor as an increase in temperature has been found to increase prolonged swimming velocity (Beamish 1978;Videler 1993). Also, fish condition may have been low during the winter months when our experiments were performed.…”

“…We selected G. maculatus because of its local abundance and availability, and to build on knowledge of swimming performance obtained from previous experiments with this species (Mitchell 1989;Boubée et al 1999;Nikora et al 2003). The experiment was performed over a small range of velocities that previous studies indicated are within the capabilities of G. maculatus (Mitchell 1989;Boubée et al 1999;Nikora et al 2003). Relatively high velocities were used to ensure the fish swam continuously (without burst and coasting) and were in a prolonged swimming mode.…”

“…Empirical time-to-fatigue relations for G. maculatus have been established in other studies with greater ranges of velocities and fish numbers including Boubée et al (1999) and Nikora et al (2003). Boubée et al (1999) presented separate time-to-fatigue relationships for sustained swimming (which they defined as durations >2 min) and burst swimming (<12 s).…”

“…It is possible that the swimming performance was inhibited by stress resulting from transferring from the holding tank to the swimming flume. However, similar short acclimatisation periods of 10-15 min were used by Mitchell (1989) and Nikora et al (2003) in studies of G. maculatus.…”

Animal perception in gravel-bed rivers: scales of sensing and environmental controls on sensory information

“…However, studies rarely account for the more heterogeneous and dynamic turbulent environment in rivers, which are likely to break up structures such as von Kármán streets under most conditions (see reviews in Lacey et al 2012;Wilkes et al 2013) and evidence for the importance of turbulence to fish distribution and behaviour is equivocal (i.e. Nikora et al 2003;Enders et al 2009). The distribution of fish in rivers has been linked to flow depth and velocity (e.g.…”