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Native fish

The Murray–Darling Basin has over 60 species of native fish – including freshwater, estuarine, marine and migratory fish. Many of these freshwater species are unique to Australia, with a number living only in the Basin

Native fish have important roles in ecosystems - as a predator, as prey and in nutrient cycling. Recreational fishing is a major pastime throughout the Basin and generates $1.3 billion annually. Native fish are culturally important to Aboriginal people. The ability to fish for food and use the basin environment for recreation and family and community gathering maintains connections to land and water. These ecological, economic and cultural values all depend upon healthy native fish populatons.

Flow has a major influence on the life cycles of native fish,  and different species respond differently to different flows. Human water use has changed flow volumes and patterns. This has degraded native fish habitat and reduced connectivity across the Basin, leading to major declines in fish numbers and the area they occupy. Nearly half of the Basin’s native freshwater fish are now listed as under threat.

Life cycle of fish

life cycle of fish flow chart

 

Basin annual environmental watering priorities for fish

To achieve the outcomes in the Basin-wide environmental watering strategy that are expected for fish, we need to provide flows that improve fish habitats and allow fish to complete their life cycles. Flows are also an important measure to protect and improve populations of threatened fish species.

Annual environmental watering priorities for 2018-19

  • support Basin-scale population recovery of native fish by reinstating flows that promote key ecological processes across local, regional and system scales in the southern connected Basin
  • improve flow regimes and connectivity to maximise the ecological function of the Barwon–Darling river system for native fish
  • support viable populations of threatened native fish, maximise opportunities for range expansion and establish new populations 

The annual environmental watering priorities are the focus for the current year and are small steps in the short term to achieve the multi-year watering priorities in the long term.

Multi-year environmental watering priorities

The annual environmental watering priorities support multi-year environmental watering priorities that remain in focus over a number of years to achieve long term outcomes. Multi-year watering provides and relies on cumulative progress over time, e.g. watering in one year may only wet a dry riverbed, but follow up watering the next year provides more water to fill the river and reach wetlands either side of the river where it waters plants and animals.

More information

The multi-year priorities are listed below:
Support Basin-scale population recovery of native fish by reinstating flows that promote ecological processes across local, regional and system scales in the southern connected Basin

This priority focuses on providing a suitable flow regime by coordinating and linking flows in different rivers for species that live, and respond to flows, in river channels and anabranches. Flows that support fish recruitment processes in spring, summer and autumn will also provide food and habitat, and connectivity between habitats. This will restore recruitment processes that promote population recovery of silver perch, golden perch, Murray cod and lamprey.

Four flow components are the focus of this priority:

  • end-of-system flows through the barrage fishways and the barrages
  • winter flows for food, habitat and connectivity between habitats within channels
  • flows that support breeding activity in spring
  • flows that support dispersal movements in spring, summer and autumn.
Improve flow regimes and connectivity to maximise the ecological function of the Barwon–Darling river system for native fish

The Barwon─Darling river system is particularly important for the recovery of native fish populations in the Murray─Darling Basin. The system supports a diverse native fish collection, comprising at least 15 native fish species, including a number of threatened species.

Water use has resulted in major reductions in the frequency and duration of flow and flood events in the Barwon─Darling. These changes to flows have reduced native fish populations.

To recover native fish in the Barwon─Darling, it is important to protect environmental water and natural flows that drive recruitment processes. Returning suitable flow regimes is vital to ensure the Barwon─Darling is able to deliver its key functions and support native fish populations.

The three key focus areas of this priority are:

  • increase the frequency of flows and improve flow variability in the Barwon–Darling to support native fish
  • protect natural recruitment flows through the Barwon–Darling to boost native fish populations
  • increase flow connections between the Barwon–Darling and its tributaries
Support viable populations of threatened native fish, maximise opportunities for range expansion and establish new populations

Almost half of the native fish species in the Murray─Darling Basin are of conservation concern. Environmental watering, alongside other measures, is a key action to improve outcomes for threatened fish.

This priority seeks to protect remaining populations of threatened species and to increase the area(s) they occupy. Water managers are encouraged to work with threatened species recovery agencies to achieve the outcomes for this priority.

To increase the area that threatened species occupy and to build fish numbers, a number of steps can be taken in a process that spans multiple years:

  • protect and boost key source populations
  • support surrogate sites and populations that can start new permanent populations
  • identify and prepare sites to establish permanent populations
  • support fish stocked into reintroduction sites and secure their long-term future.
How does the MDBA decide where water needs to be delivered?

Where and how much water for the environment is delivered depends on a number of different factors including climate (e.g. rainfall and soil moisture). These factors are measured by the Resource Availability Scenario. For more information visit the Resource Availability Scenario page.