RESEARCH by the Department of Sustainability and Environment’s (DSE) Arthur Rylah Institute (ARI) has used modern technology to provide groundbreaking insights into the migration and breeding habits of the mysterious and threatened Australian grayling (Prototroctes maraena) fish.
ARI Fish Ecologist Wayne Koster said: “The research on the Australian grayling in the Bunyip River near Koo Wee Rup was aiming to determine where they migrate to and what triggers migration and spawning. The findings plug substantial gaps in our knowledge of the species’ movement and spawning behaviours that have previously limited our ability to develop targeted management strategies for the grayling.”
“We found for the first time that Australian grayling undertook rapid long distance downstream migrations to spawn in autumn, in response to increased stream flows. Some fish travelled distances up to 40 kilometres within a few days to the lower reaches of the river,” Mr Koster said.
“As part of the work we surgically implanted 20mm long acoustic transmitters into adult fish to trace their movements throughout the Bunyip River.”
“The study has also identified specific breeding grounds, in fresh water just upstream of the estuary. This information will assist the managers of our rivers as they make decisions on the use of environmental flows and other conservation initiatives for Australian grayling.”
“The research was also able to collect and identify for the first time, Australian grayling eggs from the wild, using fine mesh nets to capture the tiny eggs (about 1mm in diameter), in conjunction with genetic testing to assist identification.”
“The research found that if flows decreased, the fish would stop their downstream migration, before recommencing migration when the flows resumed.”
“These results show that loss of natural stream flows and barriers to movement can be especially detrimental to Australian grayling populations.”
The Victorian Government has a responsibility under the Wildlife Act 1975 and the Flora and Fauna Guarantee Act 1988 to protect threatened species. These animals and plants contribute significantly to the biodiversity of their ecosystems. The knowledge we acquire about these species helps us to then take the on-ground steps needed to ensure their survival.
