Spring nesting flow for drought-hit Murray cod in the Macquarie River

Drought-hit Murray cod in the Macquarie River will receive a helping hand during their spring breeding season, with water for the environment set to be delivered throughout October and November.

Australasian bittern (Botaurus poiciloptilus)

The flow, managed by the NSW Department of Planning, Industry and Environment and the Commonwealth Environmental Water Office (CEWO), will help native fish recover after three years of record drought, and fish deaths in February and March this year.

Department of Planning, Industry and Environment's Senior Wetlands and Rivers Conservation Officer Tim Hosking, said the flow aims to balance multiple objectives including supporting Murray cod nesting season in the Mid-Macquarie River, helping with drought recovery in the Macquarie Marshes and connecting the Lower Macquarie River with the Barwon River.

"Besides being an endangered species, Murray cod are an important recreational fishing species and have significant cultural value to the First Nations in the Macquarie catchment," Mr Hosking said.

"This flow is informed by the latest science on Murray cod nesting in the Macquarie from DPI Fisheries and will deliver stable flow conditions throughout early October to help this protected species nest and move through the system".

Matt Hansen from Inland Waterways OzFish said maintaining stable flows to ensure nests are not exposed or disturbed will help to improve the likelihood of successful Murray cod breeding and support their recovery.

"After countless volunteer hours were exhausted to rescue fish through some terrible drought years, it is great to see flows designed to stimulate breeding and help the recovery. We lost thousands of fish that were decades old recently, with the intensity of the drought just proving too much," said Mr Hansen.

The Commonwealth Environmental Water Holder, Jody Swirepik, said although the Macquarie Marshes has received some decent rain, this internationally important site needs more water to recover from extended drought and fire impacts.

"Providing water during warmer spring conditions for long enough will help ensure vegetation, frogs, fish and birds can complete their lifecycles," Ms Swirepik said.

"The Macquarie Marshes are an important breeding site for a wide range of waterbirds including the endangered Australasian bittern, colonial nesting waterbirds and migratory birds.

"The flow will also help golden perch travel back into the Macquarie Catchment. We saw this happen in Autumn 2017 when flows helped connect the Macquarie and the Barwon rivers."

Monitoring by the Department during and after the flow will include remote sensing of how much of the Marshes were inundated, how long the water stayed in the landscape and surveys of how waterbirds and frogs responded. NSW DPI Fisheries will also conduct fish surveys to identify the hatching dates of larval Murray cod, to help environmental water managers tailor nesting flows more effectively in future.

The flow of up to 107 gigalitres is now possible due to recent allocations combined with carried over water that was previously suspended due to the drought. The timing and pattern of releases in late spring will benefit Murray cod and will not coincide with larger irrigation demands expected in December. Flows will be managed adaptively by local staff to make the most of the water available and mitigate, where possible, any disruptive inundation in the event of significant rainfall.

Planning for this flow has been undertaken in collaboration with the Macquarie Cudgegong Environmental Water Advisory Group, which includes landholders, irrigation and environment groups, Local Land Services, and First Nations representatives.