Communities in the Central Murray region stand to benefit from work being undertaken to improve fish populations in the Loddon River system.
A key to native fish recovery is to use water for the environment to trigger fish to move to feed and breed.
Research has shown that silver perch, yellowbelly and Murray cod need flows of 700-900 megalitres (ML) through Kerang Weir to attract them from the lower Loddon River and River Murray. This flow helps them move through the Kerang Weir fishway and into the Loddon River, Pyramid Creek and into Kow Swamp via a recently built fish lock.
Murray Cod, Loddon River, by North Central CMA
During April and May 2017, North Central CMA, GMW and the VEWH worked together to provide the right flows at the right time and make this happen.
The Loddon River system is heavily modified and primarily used to supply irrigation customers, therefore delivering the right flows at the right time threw up many challenges to the authorities.
- In order to achieve the required flow at Kerang Weir, a release of environmental water from the Loddon River was carefully timed to meet a release of irrigation water from Kow Swamp to Pyramid Creek.
- The delivery was coordinated so that there would be no impact on irrigation supply or water levels in the Kerang Lakes.
- Releases in the Loddon River were cautiously managed to ensure that landholders were not impacted, and landholders were consulted to ensure environmental water was not applied to private land without prior agreement.
- Mid-way through the delivery, releases were adapted to prevent the threat of blue green algae to the Kerang Lakes.
Staff from GMW worked 'above and beyond' the call of duty to manage and account for the water, ensuring that while the environment prospered their customers would not miss out.
The result? Scientists from the Arthur Rylah Institute trapped fish at several locations before and during the flows to test if they were working for fish. They recorded good catches of yellowbelly, silver perch and bony herring at Kerang Weir and at the 'chute' fishway on the Loddon River. Murray cod, yellowbelly and silver perch were trapped and released in the fish lock at Kow Swamp that was built by GMW. Fish that were tagged in the River Murray were detected moving through the various fishways in the system.
The flows add to works undertaken under North Central CMA's Native Fish Recovery Plan, which aims to improve flows, habitat and connectivity in waterways, providing benefits for anglers and the community of the Central Murray region. Other initiatives of the plan include introduction of 26 large woody habitat structures in Pyramid Creek, installation of fish screens on irrigation channels to stop fish being lost to irrigation networks, and fencing, weed control and revegetation along river banks. These complementary works are critical to securing the environmental outcomes of water for the environment.