Habitat use, movement and activity of two large-bodied native riverine fishes in a regulated lowland weir pool.

Wayne M Koster,Adrian Kitchingman,David R Dawson,Paul D Moloney,Robin Hale

doi:10.1111/jfb.14275

Wayne M Koster, Adrian Kitchingman + Show 3 more

Open Access

https://doi.org/10.1111/jfb.14275

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Abstract

The construction of dams and weirs, and associated changes to hydrological and hydraulic (e.g., water level and velocity) characteristics of rivers is a key environmental threat for fish. These multiple stressors potentially can affect fish in a variety of ways, including by causing changes in their movement, habitat use and activity. Understanding how and why these changes occur can inform management efforts to ameliorate these threats. In this context, we used acoustic telemetry to examine habitat use, longitudinal movement and activity of two lowland river fishes, Murray cod Maccullochella peelii and golden perch Macquaria ambigua, in a weir pool environment in south‐eastern Australia. We compared our results to published studies on riverine populations to determine if their behaviours are similar (or not). We show that M. peelii and M. ambigua in a weir pool exhibited some similar behaviours to conspecific riverine populations, such as strong site fidelity and use of woody habitat for M. ambigua. However, some behaviours, such as large‐scale (tens–hundreds of kilometres) movements documented for riverine populations, were rarely observed. These differences potentially reflect flow regulation (e.g., stable water levels, loss of hydraulic cues) in the weir pool. The two species also exhibited contrasting responses to dissolved oxygen conditions in the weir pool, which may reflect differences in their life history. Overall, this study shows that although some aspects of these two native fishes' life history can continue despite flow regulation, other aspects may change in weir pools, potentially impacting on long‐term population persistence.

Highlights

The construction of dams and weirs to store or divert water for human use has altered the condition of aquatic ecosystems worldwide (Dudgeon et al, 2006; Jo et al, 2019; Olden, 2016; Vörösmarty et al, 2010)
We found that both M. peelii and M. ambigua in a weir pool exhibit strong site fidelity, and that M. ambigua used woody debris, similar to observations on riverine populations (Crook, 2004; Crook et al, 2001; Koehn & Nicol, 2016)
The results demonstrate interspecific variability in behaviours, such as disparate responses to dissolved oxygen conditions. These differences highlight the importance of understanding species-specific fish behaviour in response to changes in environmental conditions

Summary

| INTRODUCTION

Murray cod Maccullochella peelii (Mitchell 1838) and golden perch Macquaria ambigua (Richardson 1845) are two large native riverine fish species of recreational angling and conservation significance endemic to south-eastern Australia Populations of both species have declined substantially in the MDB due to factors such as habitat degradation and loss, altered flow regimes, reduced water quality and barriers to movement (Koehn & Nicol, 2014; Leigh & Zampatti, 2013; Thiem et al, 2017; Wedderburn et al, 2017). Knowledge of aspects of life history such as habitat use, movement and activity in weir pools is needed to better understand potential impacts of habitat change and flow regulation on these two species, and to inform potential management interventions This information will potentially inform efforts to assess and mitigate future impacts on other riverine fishes experiencing the effects of flow regulation

| MATERIALS AND METHODS

| RESULTS

Findings

| DISCUSSION