Environmental flow to trigger native fish spawning

Golden and silver perch will benefit from environmental flows due to be delivered along the lower Goulburn River later this month.
Friday 3 November, 2017
Golden perch

The benefits to river health from the November flow event will be monitored as part of the Commonwealth’s Long Term Intervention Monitoring Program.

The Commonwealth Environmental Water Holder David Papps said continually building scientific understanding of what happened to the plants and animals in the lower Goulburn River when environmental water was delivered was important.

“Native fish are a barometer of river health. The more we understand about the things that fish such as golden and silver perch need to reproduce, survive and thrive, the healthier the whole system will be,” Mr Papps said.

“Our knowledge about this truly important part of life around the river has come a long way in recent times.”

Goulburn Broken CMA Environmental Water Manager Simon Casanelia said monitoring showed that the best spawning response by golden and silver perch was usually later in spring during a higher flow and when water temperatures had started to rise.

“Over the years we have refined the timing of flows to get the best spawning response, with mid to late spring being the most effective. The last time we were able to deliver an environmental flow at this time of the year was 2014 as last year natural flooding was occurring and the previous year, due to the very dry conditions and low water availability, the environmental flow was cancelled,” Mr Casanelia said.

Water for this spring’s environmental flow, peaking at 5,500ML/day, is due to be released from Goulburn Weir from November 15.

The increased flows will take about four days to reach McCoy’s Bridge near the Murray River. The river will gradually rise to about 2.9m at Murchison, 4.1m at Shepparton and 3.8m at McCoy’s Bridge before slowly returning to current levels (~0.8m at Murchison, ~2.8m at Shepparton and ~1.5m at McCoy’s Bridge) by late November. These increases in river flow and height will be well below minor flood level (9m at Murchison and 9.5m at Shepparton). In the event of heavy rain, the timing and size of the environmental flow could change or not go ahead at all.

The environmental flows will also act as a trigger for other native fish to move, breed and find shelter, provide increased shelter for water bugs and improve water quality.

“This will help crayfish, shrimps, water bugs and native fish continue to recover after the naturally occurring blackwater event that happened earlier this year after a summer storm,” Mr Casanelia said.

“Irrigators appreciate better water quality too and of course, now the weather has warmed up, more people will be out and about on and by the river boating, fishing, bushwalking and birdwatching.”

Environmental flows are planned by the Goulburn Broken CMA in consultation with the Commonwealth Environmental Water Office and managed by Goulburn-Murray Water in line with the Victorian Environmental Water Holder’s Seasonal Watering Plan 2017-18. Timing of the environmental flows takes into consideration delivery orders by irrigators and other water users and feedback from the community via the Goulburn Broken CMA’s environmental water advisory groups.  If you are interested in participating in the environmental water advisory groups, please contact the Goulburn Broken CMA.

Using water for the environment is only one of many ways of protecting and improving the health of rivers and wetlands. Fencing and revegetation, erosion control, pest control, returning logs to rivers for fish and bug habitat and installation of fishways to allow fish to pass through dams and weirs also help. Find out more about these activities here.