Flow‐mediated movement of freshwater catfish, Tandanus bostocki, in a regulated semi‐urban river, to inform environmental water releases

Abstract

Movement and migration of fish are critical for sustaining riverine fish populations. Water resource development alters natural flow regimes and can disconnect habitats and interfere with hydrological cues for fish movement. Environmental flow releases can counter these impacts, but to be effective they must be based on quantitative flow–biota relationships. We used radio‐telemetry to investigate the association between flow and movement of Tandanus bostocki, a plotosid fish endemic to south‐western Australia. Movement was assessed for 15 adult fish at three temporal scales: weekly, daily and bihourly to reveal seasonal patterns in movement, movement around individual flow pulses, and to describe changes in home range respectively. We used a predictive modelling approach to assess the importance of discharge and other covariates on the directional distance travelled or linear home range size. Our seasonal and flow pulse study revealed that T. bostocki undertook larger downstream movements during higher flows and smaller upstream movements during lower flows. Daily movements tended to be downstream on the ascending limb of flow pulses and upstream on the descending limb. Flow‐dependent movements at weekly or daily time scales were relatively modest (typically hundreds of metres) and were moderated by time of year and gender; however, fish underwent a synchronised 1‐km movement upstream during the known reproductive period in October. The home range study revealed that T. bostocki had larger home ranges (night‐time foraging) when baseflow was elevated. These results can assist the design of customised environmental flows in the study river and other flow‐regulated rivers.

Influence of discharge regime on the movement and refuge use of a freshwater fish in a drying temperate region

“…Higher flows may facilitate the movement of T. bostocki over riffles and shallow runs however this effect would vary greatly depending on river morphology, particularly along river gradients that dictate the prevalence of instream barriers. Beesley et al (2019) radio‐tracked the species in another regulated river and reported downstream movements during winter (mostly on the ascending limbs of flow pulses) followed by shorter, upstream movements in late spring. Similar responses to elevated flow have been reported for the congeneric eel‐tailed catfish Tandanus tandanus in Queensland, with movements restricted to limited home ranges during dry periods, and large‐scale migrations in both upstream and downstream directions occurring during high‐flow events (particularly in response to the first post‐winter flow; Burndred, Cockayne, Donaldson, & Ebner, 2019; Marshall et al, 2016).…”

“…A previous study on T. bostocki in the larger, unregulated and low gradient Blackwood River (a mark‐recapture study that employed external t‐bar tags) recorded over 20% of 437 individuals being recaptured at least once with all but one fish (that moved downstream 15.5 km in ~3 months) recaptured from the same location (Beatty, Morgan, Mcaleer, & Ramsay, 2010). Beesley et al (2019) also found that the species had a relatively small home range and undertook only localized migrations in the Canning River. These findings are consistent with studies on T. tandanus , which also reported high levels of site fidelity to restricted home ranges and accurate homing to previous occupied locations following flow‐related, large‐scale movements (Burndred, Cockayne, Donaldson, & Ebner, 2019; Koster et al, 2015; Marshall et al, 2016).…”

“…In an unregulated river, Beatty, Morgan, Mcaleer, and Ramsay (2010) demonstrated that perennial baseflow derived from groundwater maintained the migratory pathways for T. bostocki and it was therefore proposed as a candidate indicator species of river connectivity. Beesley et al (2019) conducted a radio‐racking study of T. bostocki over a short section of the regulated Canning River over an approximately 8‐month period to determine the effects of flow and time on its movement and revealed that it undertook downstream movements during high flows and smaller upstream movements during low flow events. Understanding how the movement patterns of the species may vary between rivers and over longer temporal scales, and considering the effect of other predictive variables, would further add to our understanding of the drivers of its movements.…”

“…However, these patterns are also known to be highly species dependant (e.g., Hodges & Magoulick, 2011). Beesley et al (2019) found that T. bostocki had a relatively small home range in the Canning River. They also found that its home range increased positively with baseflow, with these movements attributed to night‐time foraging.…”

Distribution of migratory fish in the stream (depth, velocity, body size, predators)

“…The movement and migration of fish is important for maintaining populations of various fish species, including river fish. The development of hydro-construction changes the natural flow regimes and can fragment habitats, creating insurmountable barriers (Santos et al, 2016;Mao, 2018;Beesley et al, 2019) not only for anadromous and potamodromous, but also for resident fish species (Enders et al, 2017), as a result of which the number of fish may decrease (Radinger & Wolter, 2014;Santos et al, 2016). To overcome the artificial barriers, special fish passages are being built -fish passages that help the fish to reach their spawning and feeding grounds.…”