What is needed to restore native fishes in Australia’s Murray–Darling Basin?

Koehn, John D.; Balcombe, Stephen Richard; Baumgartner, Lee J.; Bice, Christopher M.; Burndred, K. R.; Ellis, Iain; Koster, Wayne; Lintermans, Mark; Pearce, Luke; Sharpe, Clayton; Stuart, Ivor G.; Todd, Charles R.

doi:10.1071/mf20248

Cited by 16 publications

(17 citation statements)

References 6 publications

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“…For instance, expanding the range of silver perch is a management objective that could be targeted by incorporating small to moderate variations in discharge, especially timed between September and February to promote upstream movement along the Murray River and other perennial lotic rivers where populations have declined. This must be complemented with additional measures (e.g., habitat enhancement, barrier remediation and mitigation of cold water pollution) as there are many other factors or threats that potentially affect recovery (Baumgartner et al, 2014; Baumgartner, Gell, Thiem, Finlayson, & Ning, 2020; Koehn et al, 2020). The importance of regular small to moderate discharge pulses in cueing movement has been proposed for numerous other riverine fishes (Beesley et al, 2019; Reinfelds, Walsh, van der Meulen, Growns, & Gray, 2013) and is also an important component for ecosystem restoration within a broader environmental flow regime (Arthington & Balcombe, 2011; Stuart & Sharpe, 2020).…”

Section: Discussionmentioning

confidence: 99%

Environmental influences on migration patterns and pathways of a threatened potamodromous fish in a regulated lowland river network

et al. 2020

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In riverine ecosystems, movements of biota among different parts of the river network are fundamental to the functioning and sustainability of populations, especially for fish. Globally, human activities (e.g., dam construction and altered flow regimes) have impaired riverine fish movements through reduced river connectivity, leading to well‐documented population declines. This study examined the timing and extent of movement of a nationally threatened potamodromous fish, silver perch (Bidyanus bidyanus), among different parts of the mid‐Murray River network in south‐eastern Australia using acoustic telemetry to identify the relative importance of different environmental variables (including river discharge) influencing timing and extent of movements. A total of 203 silver perch (fork length range 120–415 mm) was tagged in the Murray River. Silver perch occupied extended reaches of river (hundreds of kilometres) and multiple habitats throughout the river network, ranging from a large mainstem river to inflowing tributaries, anabranches and floodplain habitats. Movements were associated with aspects of the flow regime, such as small to moderate mainstem discharge rises and elevated tributary discharge. These results emphasise the importance of managing silver perch populations within an integrated riverscape context rather than solely focusing on reach/river scales. The inter‐relationship between silver perch movement and river discharge highlights the susceptibility of the species to river regulation, which has previously been implicated in its decline. The information on migratory behaviours in this study provides empirical evidence to support refinement and implementation of targeted restoration strategies, such as environmental flows, to assist the management and conservation of an imperilled species.

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Section: Discussionmentioning

confidence: 99%

Environmental influences on migration patterns and pathways of a threatened potamodromous fish in a regulated lowland river network

et al. 2020

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“…There may no longer be enough water remaining in the Darling River due to overallocation and a drying climate to avoid such catastrophic conditions being repeated (Australian Academy of Science 2019; Rowland 2020). The water management stressors raised for the Darling River (Australian Academy of Science 2019; Vertessy et al 2019;Walker 2019;Mallen-Cooper and Zampatti 2020;Beasley 2021) must be taken seriously and addressed, in addition to the many other options for both restoring native fish populations and increasing their resilience to climatic variability (Koehn and Lintermans 2012;Koehn et al 2020b;. Such approaches must be adapted to accommodate climate change predictions (Pittock and Finlayson 2011).…”

Section: Management and Resourcingmentioning

confidence: 99%

“…There are also many other recommendations for beneficial water management actions, including those to reduce the likelihood of blackwater events (Kerr et al 2013;Whitworth and Baldwin 2016) and to build resilience in fish populations (Koehn et al 2020b;.…”

Section: Management and Resourcingmentioning

confidence: 99%

“…Given the poor state of MDB fishes, in addition to short-term actions there also must be a longer-term focus towards building resilience in populations and their general recovery, not just following fish-kill events (Koehn and Lintermans 2012;. Many other management actions, such as fishways that help in dispersal, recolonisation and recovery, preventing loss of larvae over weirs, can reduce existing stressors (Baumgartner et al 2020;Koehn et al 2020b).…”

Section: Management and Resourcingmentioning

confidence: 99%

“…Species rescue and recovery facilities should be established to capture, house and, where practical, breed fish and then release them back into the wild. This is especially important for small-bodied threatened species (Koehn et al 2020b;Lintermans et al 2020).…”

Section: Management and Resourcingmentioning

confidence: 99%

See 2 more Smart Citations

Key steps to improve the assessment, evaluation and management of fish kills: lessons from the Murray–Darling River system, Australia

Koehn

2021

Mar. Freshwater Res.

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Fish kills are very visible, with high levels of public scrutiny and major effects on populations. In 2018-19, extensive fish kills in the lower Darling River, south-eastern Australia, resulted in the deaths of millions of fish, including threatened and popular, iconic angling and important cultural species. This distressed local communities and the broader Australian society, who questioned the competence of fish and water management. Fish kills are increasing in frequency and severity, exacerbated by climate change. This paper reports on eight major fish-kill case studies across the Murray-Darling Basin that were examined to assess management adequacy. Field assessments and reporting have been poor, not documenting all species or numbers affected. Few values of fishes (cultural, conservation, recreational, social, ecological, economic) have been assessed and replacement or management costs not determined. There is a need to philosophically change our approach to take fish kills more seriously. More comprehensive approaches to assessment, evaluation and management are needed. Responsibilities for fish kills should be clarified and include water and habitat management agencies. Post-kill recovery plans that include the replacement of lost ecological assets should be published and enacted. This paper provides a fresh perspective on fish kills, with 15 key recommendations applicable to improve future management worldwide.

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Occupancy modelling confirms the first extirpation of a freshwater fish from one of the world's largest river systems

Wedderburn

Whiterod²,

Vilizzi

2021

Aquatic Conservation

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Numerous human‐induced changes to freshwater ecosystems are implicated in the loss of biodiversity, including fish extinctions. Dams and weirs have profoundly altered the ecological character of the Murray–Darling Basin (MDB), one of the world's largest river systems, which discharges at the mouth of the River Murray in South Australia. These impacts are evident in the Ramsar‐listed final reaches of the river, where regulation, drought, and flow reductions over recent decades have led to the collapse of freshwater fish populations, including Yarra pygmy perch (Nannoperca obscura), which is Endangered on the International Union for Conservation of Nature Red List of Threatened Species. Nannoperca obscura occurs in several major catchments in south‐eastern Australia, but the genetically unique population in the MDB only inhabits wetlands near the terminus of the River Murray where wild populations were last recorded in 2008 approaching the end of a prolonged drought. This study involved repeated surveys targeting N. obscura to evaluate its occupancy in the MDB while accounting for imperfect detection. The surveys failed to find N. obscura despite regular detection of the closely related southern pygmy perch (Nannoperca australis), which provides a proxy for the congener. This study presents strong evidence that N. obscura is absent in the survey region, thereby inferring the first freshwater fish extirpation from the MDB. The outcomes of this study should prompt responses required to aid the species' population recovery and present a reliable approach to confirm the status of freshwater fishes for conservation management.

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What is needed to restore native fishes in Australia’s Murray–Darling Basin?

Cited by 16 publications

References 6 publications

Environmental influences on migration patterns and pathways of a threatened potamodromous fish in a regulated lowland river network

Environmental influences on migration patterns and pathways of a threatened potamodromous fish in a regulated lowland river network

Key steps to improve the assessment, evaluation and management of fish kills: lessons from the Murray–Darling River system, Australia

Occupancy modelling confirms the first extirpation of a freshwater fish from one of the world's largest river systems

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