Lachlan flows for fish breeding

Environmental water flows in the Lachlan River through to November aim to boost breeding opportunities for native fish including Murray cod, which require a steady flow during their breeding season and keep their nests under water.

Office of Environment and Heritage environmental water manager Paul Packard said designing river flows for native fish can be complex with different species requiring specific flows at differing times through all their life stages.

“Managing water to allow all 17 native fish species in the Lachlan River to breed, survive and thrive can be as fluid as the life-giving liquid itself,” Mr Packard said.

“This year, flows for fish in the Lachlan River will be made up of several separate events during the next six months using up to 50 GL from a combination of Environmental Water Allocations. 

“The first flow, commencing in late September and continuing through to November is supporting breeding opportunities for species like Murray cod, which require stable flows over their nest sites whilst they guard their developing eggs.

“The aim is to provide enough water to have a more even flow between the rises and falls created by other users such as irrigation and town water supply.

“A small rise at the end of November will create a flush to distribute the newly hatched young fish and help with food production for hungry little mouths.

“Other fish such as Freshwater catfish, Australian smelt, carp-gudgeons and Murray-Darling rainbowfish are also likely to benefit from these flows.

“All flows will stay within the channel.

“The residual flows to the Great Cumbung Swamp in late spring will replenish the reed beds and wetlands in the core of the swamp.

“Another fish flow is planned for summer when temperatures are likely to be high and if a natural rainfall event creates a pulse in the river.

“The intention is to try and work with nature rather than recreate it entirely from water released from dams and other storages.

“This flow could potentially trigger spawning and create movement opportunities for fish that respond to higher flows at warmer temperatures, such as Golden perch and Silver perch.

“A small replenishment flow in Autumn will give fish an opportunity to move into favourable habitat and have a chance to put on body condition before winter,” Mr Packard said.