Swimming performance traits of twenty-one Australian fish species: a fish passage management tool for use in modified freshwater systems

Abstract

Freshwater ecosystems have been severely fragmented by artificial in-stream structures designed to manage water for human use. Significant efforts have been made to reconnect freshwater systems for fish movement, through the design and installation of dedicated fish passage structures (fishways) and by incorporating fish-sensitive design features into conventional infrastructure (e.g. culverts). Key to the success of these structures is making sure that the water velocities within them do not exceed the swimming capacities of the local fish species. Swimming performance data is scarce for Australian fish, which have a reduced swimming capacity when compared to many North American and European species. To help close this knowledge gap and assist fisheries management and civil engineering, we report the swimming performance capacities of twenty-one small-bodied fish and juveniles (< 10 cm) of large bodied species native to Australia as measured by critical swimming speed (Ucrit) and burst swimming speed (Usprint) in a recirculating flume. This data is complemented by endurance swim trials in a 12-meter hydraulic flume channel, and by measures of flume traverse success. Building on the utility of this dataset, we used a panel of morphological, behavioural and ecological traits to first assess their relative contributions to the observed swimming performance data, and second, to determine if they could be used to predict swimming performance capacity -a useful tool to assist in the management of species of conservation concern where access to swimming performance data may be limited. We found that body length combined with depth station (benthic, pelagic or surface) explained most of the interspecific variation in observed swimming performance data, followed by body shape and tail shape. These three traits were the most effective at predicting swimming performance in a model/unknown fish. This data will assist civil engineers and fisheries managers in Australia to mitigate the impact of in-stream structures on local fish populations.

Low light intensities increase avoidance behaviour of diurnal fish species: implications for use of road culverts by fish

“…Silver Perch activity patterns in the wild are generally greatest during daylight hours, however, they do not appear to be actively inhibited by darkness and can be trapped, albeit at lower frequencies, at night (Baumgartner et al 2008). In the present study, we were unable to disentangle a behavioural response to light levels from their response to water flow direction (rheotaxis), which may have been exacerbated by the relatively slow flow velocities used in this study compared to their swimming capacity (Watson et al 2019). For the two species that avoided the darkened environment, we found that the threshold light intensities needed to encourage individual fish to enter the darker half of the test channel were quite low.…”

“…The channel bulk velocity was set to 0.3 m s-1 and the depth set to 0.15 m, measured at the mid-point, 6 m along the channel length. This velocity was chosen as it was significantly below the maximum sustainable swimming speed (Ucrit; Brett 1964) of all four species tested (Watson et al 2019) so as to minimise any effect that swimming capacity, or their innate rheotactic response, could have on their subsequent behaviour. The water temperature was maintained at 25 ± 1°C.…”

Low light levels increase avoidance behaviour of diurnal fish species: Implications for road culverts

“…Silver Perch activity patterns in the wild are generally greatest during daylight hours, however, they do not appear to be actively inhibited by darkness and can be trapped, albeit at lower frequencies, at night (Baumgartner et al 2008). In the present study, we were unable to disentangle a behavioural response to light levels from their response to water flow direction (rheotaxis), which may have been exacerbated by the relatively slow flow velocities used in this study compared to their swimming capacity (Watson et al . 2019).…”

“…The channel bulk velocity was set to 0.3 m s-1 and the depth set to 0.15 m, measured at the mid-point, 6 m along the channel length. This velocity was chosen as it was significantly below the maximum sustainable swimming speed ( U crit; Brett 1964) of all four species tested (Watson et al 2019) so as to minimise any effect that swimming capacity, or their innate rheotactic response, could have on their subsequent behaviour. The water temperature was maintained at 25 ± 1°C.…”

Native fish losses due to water extraction in Australian rivers: Evidence, impacts and a solution in modern fish‐ and farm‐friendly screens

“…Velocities in front of a typical trash rack can be as high as a few metres per second, exceeding the swimming capabilities of larval, juvenile and adult fish (Kopf et al . 2014; Watson et al in review). Therefore, smaller fish and debris may be sucked into the pump, while larger ones may be impinged on the trash rack.…”