River flow impact on native fish populations

Thursday 27 April, 2017
A decade of annual surveys in the Goulburn River has provided researchers with a clearer understanding of the impacts of flow events on native fish populations.

Fish ecologist Wayne Koster from the Arthur Rylah Institute for Environmental Research spent several weeks at a number of testing sites to gauge changes in fish population.

 Mr Koster said the surveys were part of a long-term program to restore aspects of the flow regime.

“The surveys are conducted annually. They involve a fish tagging program to help understand the movement behaviours of fish and how fish respond to flow events,” he said.

 Species researched as part of the program include Golden Perch, Silver Perch and Murray Cod.

 Mr Koster said species such as Golden Perch required increases in flows during spring to initiate breeding.

 The research team used electrofishing technology to safely bring fish to the water surface.

 Among the key findings was that some species undertook long distance migration in spring to facilitate breeding.

 “We’ve found that Golden Perch are travelling up to 150 kilometres and those migrations are prompted by increases in flows - without those increases fish fail to breed,” Mr Koster said.

 The research also revealed that a blackwater event in the river earlier this year had devastated breeding patterns of native fish.

 “The blackwater event has had a negative impact on native fish populations and that can take years and years to recover, which is why conservation measures such as restoring natural flow conditions will be important to giving the fish a kick along. The main value of the work is to understand the flow conditions that native fish need to survive and using that information to inform how we manage our waterways to benefit fish populations using limited water resources.”

 The Commonwealth Environmental Water Holder’s Long-Term Intervention Monitoring Project in the Goulburn River is a collaboration between the Goulburn Broken CMA, University of Melbourne, The Arthur Rylah Institute (Department of Environment, Land, Water and Planning), Monash University, Streamology, Goulburn Valley Water and Jacobs. More about monitoring in the Goulburn River is available here.

Golden perch