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Native fish play an important role in the environment. The Murray–Darling Basin has over 60 species of native fish including freshwater, estuarine and those that move between the river and the sea. Many of these species are unique to Australia, with a number living only in the Murray–Darling Basin.

A healthy native fish community helps keep the river healthy by cycling nutrients like carbon and nitrogen and maintaining healthy food webs.  

We need to protect and restore native fish communities to improve the health of our rivers.

Water for the environment protects native fish

How we use water in our rivers, has changed natural flow volumes, timings and patterns of rivers. River flows affect the life cycles of native fish, and different species require different flows. Barriers, like dams, weirs and very dry climate conditions (which can stop the rivers running) can prevent native fish getting to where they need to be, to reach food and breeding areas.

Water for the environment, complements other management techniques like fishways and snags, and is used to improve native fish populations, including threatened species. Providing flows in the right time at the right place helps native fish swim to where they need to be to feed, grow and breed.

The goal is to maintain and improve the health of native fish populations, which will help to restore the entire health of the river system to health.

Most native fish species need the following:

Eggs:

  • Healthy habitat to protect them from predators while they grow
  • Good water quality to survive and grow
  • Flowing rivers to reach the right habitat (for some fish species)
 

Larvae:

  • Suitable nursery habitat and food webs  to feed and grow 
  • Good water quality to grow
  • Healthy habitats to feed and hide from predators
 

Juvenile or young fish:

  • Seasonal flows to tell them when to move to feed and grow
  • Healthy habitat to feed and hide from predators
  • Good water quality to live and grow

Adult fish:

  • Connected rivers to reach the right habitat for different life stages, eg some fish need to find specific habitats to breed
  • Flowing rivers to tell them when to breed
  • Connected rivers to find food when conditions change, eg too hot or cold
  • Good water quality to breathe, feed and breed

Native fish are important for people

Native fish have a large social and cultural value to Basin communities. Recreational fishing is a major pastime throughout the Basin and generates $1.3 billion annually. Healthy fish populations are needed so recreational fishers can keep fishing.

Native fish are culturally important to First Nations. The ability to fish for food and use the Basin environment for recreation and family and community gatherings maintains connections to land and water.

These environmental, economic and cultural values all depend upon healthy native fish populations. Releasing water for the environment helps to restore native fish populations so all of us can benefit from healthy rivers.

Deciding where water goes to help fish

This year: annual environmental watering priorities for fish

The annual priorities are a guide for where water should be provided for the current year to improve the health of plants and animals for the overall health of the Basin over the long term, as set out in the Basin watering strategy.

2020–21 priorities for native fish are:

  • Protect or provide flows that protect existing populations, support connectivity and sustain short-lived species recruitment.
  • Support recruitment from breeding events and subsequent dispersal of new recruits in the northern Basin.
  • Maintain existing populations and ensure hydrological integrity of flow pulses in the southern Basin rivers.

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.

One important factor used to decide how much water to provide for the environment each year is the resource availability scenario. This is based on climate conditions (rainfall, runoff and soil moisture), surface water availability in dams and the climate outlook.

Longer term: rolling, multi-year environmental watering priorities

The annual environmental watering priorities support rolling, multi-year environmental watering priorities that guide watering over the medium-term (the next 3-5 years) based on different conditions, from very wet to very dry.

Multi-year watering provides and relies on cumulative progress over time. For example, watering in one year may trigger fish to lay eggs, but follow up watering is then needed to provide more food and habitat, increasing the chances of young fish surviving and becoming adults.