Fish flow in the Loddon
Picture yourself getting in your car to drive to the supermarket. You go down the driveway, turn left at the corner and immediately crash into a brick wall built across the road.
You look behind you and see other people who are also stuck. Like you, some are going to do their shopping, others are trying to get to their boyfriend’s or girlfriend’s house.
You can’t get around the wall, and there aren’t any other roads to access. You’re trapped. You can go home, but sooner or later you’re going to start getting hungry.
Welcome to the world of being a native fish in the Murray Darling Basin.
Irrigation and river regulation has trapped fish between regulators, weirs and dams. They can’t get to their preferred breeding grounds and, while they can smell food in reservoirs and other rivers, they can’t get through.
The North Central Catchment Management Authority (CMA) has been working with Goulburn Murray Water to build a series of fishways at weirs and regulators, to help fish get to where they need to go.
Two new fishways – on the Loddon River at Canary Island, and Box Creek at Kow Swamp – have opened up hundreds of kilometres of feeding and breeding grounds to some of Australia’s most vulnerable native fish.
“For fish, movement is vital for survival,” North Central CMA Environmental Water Manager Louissa Rogers said.
“Before European occupation, fish knew when it was time to breed. The river would flow, and they would smell the food, moving to safe breeding grounds in the river and on the floodplain in wetlands.
“Regulation has turned all that upside down, and even when the rivers do flow, fish can’t move upstream to where they want to go.”
But the infrastructure is only part of the solution.
“We can build all the fishways we want, but the fish have to be encouraged to move, and to move safely,” Ms Rogers said.
“Our Native Fish Recovery Plan is working to install snags in rivers and creeks to give them safe places to rest and feed, and we are fencing off and revegetating waterways to help with food for the fish.
“But the real hero in all of this is water for the environment. By managing the right amount of water at the right time, we can give these fish exactly what they need.”
A series of coordinated flows down the Pyramid/Box Creek and Loddon River in autumn and spring was designed to do exactly that.
“We were able to make sure the water all came together at the Loddon Weir at the same time, giving fish in the Murray River the chance to swim up the Loddon and up Pyramid/Box Creek into Kow Swamp.”
And swim they did.
“The Arthur Rylah Institute trapped fish in fishways, monitored them acoustically and electro fished at various spots before and during the flows,” Ms Rogers said.
“Only four species of native fish were found before the flow, and seven during, which is great news. The numbers of fish moving through the Loddon chute fishway near Canary Island and at the Kerang Weir increased substantially during the flow.
“They also recorded significant movement of both critically endangered silver perch and golden perch in the lower Loddon part of the system during the flow, which is brilliant. In fact, it’s more than brilliant. Critically endangered is the highest listing an animal can have before they become extinct. Silver perch moving to breed is key to saving the species.
“And on top of this, the flows that entered the Murray River were can be re-used by other users downstream, making every drop count twice.
“Water for the environment is aimed at rehabilitating rivers and what lives in them, helping them recover from drought and floods, and building resilience to help them survive the next one.”
Fish monitoring was conducted as part of the Victorian Environmental Flows Monitoring and Assessment Program (VEFMAP), funded through the Victorian Government’s $222 million investment over 2016-2020 to improve the health of waterways and catchments.
The flows were authorised by the Victorian Environmental Water Holder in line with its Seasonal Watering Plan 2017-18.
The VEWH Seasonal Watering Plan 2017-18 is available for download from www.vewh.vic.gov.au, with regular watering updates posted on the North Central CMA website