Twelve of Australia’s top fisheries scientists have come together with a summary of 30 priority actions urgently needed to restore MDB native fishes.
All of us who care for native fish can use this summary to support our own efforts – whether it be applying for grants, lobbying policy makers or restoring the habitats in which native fish can thrive. The following summary is adapted from the full journal paper ‘What is needed to restore native fishes in Australia’s Murray–Darling Basin?’ which is free to access here.
The Murray–Darling Basin (MDB) is Australia’s food bowl, contributing 40% of agricultural production and supporting a population of over 4 million people. Historically, the MDB supported a unique native fish community with significant cultural, subsistence, recreational, commercial and ecological values. Approximately one-quarter of the MDB’s native species are endemic (found only in the MDB). Changes to river flows and habitats have led to a 90% decline in native fish populations over the past 150 years, with almost half the species now of conservation concern. Commercial fisheries have collapsed, and important traditional cultural practices of First Nations People have been weakened.
The past 20 years have seen significant advances in the scientific understanding of native fish ecology, the effects of human-related activities and the recovery measures needed. The science is well established, and some robust restoration-enabling policies have been initiated to underpin actions. What is now required is the political vision and commitment to support investment to drive long-term recovery.
Restoring MDB native fishes requires:
A: Coordinated policy settings under which actions can be implemented
B: Sound supporting science
C: Prioritised actions
D: Commitment and investment
E: Stakeholder and community support
We have the policy settings and management frameworks, such as the Basin Plan and Native Fish Recovery Strategy (NFRS) to pursue these restoration goals, and the supporting science are strong. It is now political commitment, and implementation of restoration actions, that is critical.
The 30 priority actions required for the restoration of native fish populations can be categorised into:
- Flow management
- Water infrastructure
- Other restoration (actions to be implemented in parallel with appropriate flow management)
- Support and engagement
1. Flow Management
Altering river flows (depth, quantity, timing) causes a raft of threats to fishes, and key flow components need to be restored.
- Design, implement and manage coordinated, optimised flow regimes (multiyear or decadal) for all water (environmental water, stock and domestic, irrigation deliveries, protection of natural flows) that permanently support native fishes and ecosystem processes at the appropriate scales.
- Incorporate specific, designed flow components into annual flow hydrographs that restore hydrodynamic (flow variability) diversity, cue spawning, movements and dispersal, including for diadromous fishes (move between the sea and river) at the Murray River mouth.
- Allow overbank flows to restore and support riverine productivity and food webs, connect floodplain habitats, including fish nursery areas, and maintain temporary, seasonal and perennial wetlands through relaxation of ‘constraints’ (see Murray-Darling Basin Authority 2013).
- Develop and implement preventative strategies to minimize fish kills and poor water quality: real-time water quality monitoring at high-risk sites; maintaining adequate flows; the use of flushing flows, including periodic reductions in floodplain carbon to minimise hypoxic (no oxygen) blackwater events.
- Protect free-flowing tributaries and anabranches, drought refugia, remnant waterholes and off-channel wetland habitats from water extraction (e.g. moratorium on pumping) through policy, strategic planning, conjunctive groundwater management with consideration of climate change environmental projections (Pittock and Finlayson 2011) and the provision of water.
- As a minimum, maintain adequate base flows across the year in perennial (constant flow) rivers to support existing populations, recent recruits and connectivity between rivers (source to sea), floodplains and wetlands.
- Manage water levels in lakes and reservoirs to achieve desired outcomes for native fishes (e.g. protect fringing vegetation as habitats for small fishes such as pygmy perches (Nannoperca spp.), facilitate river connectivity for Macquarie perch (Macquaria australasica) spawning migrations in impoundments).
- Ensure all water use planning and management uses appropriate contemporary fish ecology, appropriate spatial scales and suitable flow records that incorporate climate change projections
2. Water Infrastructure
The management of water infrastructure (dams, weirs, channels) can be improved to reduce effects on fish.
- Provide effective fish passage for all life stages (upstream, downstream and laterally to floodplain channels and wetlands) at priority barriers and remove redundant structures.
- Replace undershot riverine weirs with overshot weirs to reduce larval mortality.
- Protect existing flowing (lotic) habitats and in regions where unnatural lentic (still) weir pools now predominate (e.g. lower Murray River), restore such habitats to increase hydrodynamic habitat diversity by weir pool lowering and increased discharge.
- Prevent the large-scale loss of fish (especially early life stages and small species) through pumps and irrigation diversion infrastructure.
- Ameliorate cold water pollution released from priority impoundments.
- Assess whether planned new infrastructure is needed; explore alternative water supply strategies (e.g. off-stream storages) and ensure new structures do not further compromise fish populations by explicitly considering and remediating effects on the entire life cycle (from eggs to adults).
3. Other Restoration Actions
A range of other restoration actions can complement those for water management and infrastructure.
- Protect existing threatened species populations and create additional populations through translocations or hatchery stocking; establish hatchery facilities for the production and stocking of conservation-dependent species.
- Increase instream structural woody habitats at priority sites.
- Eliminate stock access and control terrestrial animal (feral and stock) effects, particularly at sensitive river and wetland sites.
- Protect and restore macrophyte habitats (reeds, sedges) and riparian (riverside and floodplain) vegetation.
- Implement threatened species recovery plans, overseen by active, suitably funded recovery teams.
- Undertake sustained, strategic control of alien fishes (e.g. Redfin perch Perca fluviatilis, Carp, Eastern gambusia Gambusia holbrooki and salmonid species) using pest management principles.
- Implement a Basin Alien Fishes Plan, complete a National Pest Fish Strategy and proactively prevent new incursions (e.g. Tilapia; Oreochromis mossambicus and Tilapia mariae).
- Monitor fish population structures and quantify losses due to extreme events (such as fish kills), river operations and angler harvest of recreational species (Murray cod Maccullochella peelii, Golden perch Macquaria ambigua, Silver perch Bidyanus bidyanus, Macquarie perch, Freshwater catfish Tandanus tandanus and incidental catch of Trout cod Maccullochella macquariensis), including catch-and-release mortalities, to ensure population sustainability.
- Establish and resource a threatened fish rescue and recovery facility to house, breed and ultimately return rescued fish to the wild following extreme events such as bushfires and drought.
- Adequately fund and implement the Native Fish Recovery Strategy for the MDB.
4. Support and Engagement
All actions require public, agency and stakeholder support. We need to ensure the public are champions for the restoration of MDB fishes.
- Build public support for the restoration of MDB fishes from relevant stakeholder groups, including recreational fishers, peak agriculture groups, irrigation and rural communities, First Nations People and the general public.
- Ensure fish are prioritised equally compared with terrestrial flora and fauna, through inclusion in water and natural resource (including national parks) management plans, the development of a National Freshwater Fish Action Plan and inclusion in the National Threatened Species Strategy.
- Ensure that the concerns and values of First Nations People are represented in all plans and policies that relate to water use, flows, fish and conservation management.
- Establish fish champions (local, regional, Basin-wide) to drive advocacy for native fish restoration and embed native fish recovery in government agendas relating to water resource management.
- Provide material for inclusion into the Australian educational curriculum regarding native freshwater fishes, their plight, and recovery potential.
- Promote awareness of MDB fishes and their values to the Australian public through traditional and social media.
These thirty recommended actions can be used to guide our work to save the MDB’s native fish and, indeed, there is some work being undertaken in many of the areas outlined. The problem is, however, that we are not doing enough.
The MDB and its fishes are under great stress and without urgent action there will be species extinctions in the coming decades. We must act quickly to address key threats, through committed and sustained recovery efforts). Consideration needs to be given to all fishes across the MDB, from alpine regions, through lowland rivers to the sea, including lesser known small-bodied diadromous and estuarine species.
Immediate commitment is needed now from policy makers, management agencies, community and, most importantly, governments, because they are the final arbiters of implementation. It is not the science or the policy structure that is preventing meaningful fish recovery programs, it is a lack of action and political will. Provision of additional, relevant and accurate information on the plight of MDB fishes to the public will result in support, given that Australians care deeply about their environment and its protection (Samuel 2020). Unfortunately, misinformation has contributed to an ‘increasingly toxic’ and ‘divisive’ public debate surrounding environmental water (Interim Inspector-General of Murray–Darling Basin Water Resources 2020). This needs to be addressed with improved messaging about the benefits to all Australians and their river systems of environmental water.
The science and knowledge of MDB fishes is considerable and growing. Knowledge is not a constraint to species and ecosystem restoration, but additional information will help maximise outcomes. Two key policy frameworks in the Basin Plan and NFRS provide a solid basis from which recovery can begin. Contemporary science needs to reach managers and policy makers, be accepted and incorporated to improve water and fish management and to build community support. The challenge now is to have the long-term political will, commitment and adequate resourcing to implement the necessary actions. Providing a legacy of native fish recovery in the MDB, rather than extinctions, is our moral obligation to Australia’s future generations.
Banner Photo: Fish sampling on the Yass River. Photo: Ben Broadhurst
Flow Management: Flooded wetland in the MDB. Photo: Tanya Doody
Water Infrastructure: Mollee Weir, New South Wales. Photo: Craig Copeland
Other Restoration Actions: Resnagging at Bowenville Resever. Photo: Condamine Alliance
Support and Engagement: Ross Webster from Yass Angling Fishing Club, Feeling Fishy Field Day. Photo: Richard Snashall