Fish flourish from flows
Researchers have discovered a spike in Wimmera native fish numbers including a rapid spread of the previously declining Southern Pygmy Perch from the Grampians all the way to Horsham.
Wet conditions during the past two years, combined with regular environmental flows, have boosted fish numbers in specific waterways and allowed them to repopulate areas affected by years of drought.
Researchers also discovered several River blackfish as well as flat-headed gudgeon in the Mackenzie River downstream of Grampians National Park, the first recording of the species at this location for several years.
The findings are in stark contrast to conditions in the upper reaches of the Wimmera River system north-east of Ararat, where DNA research has revealed a decline in some aquatic species.
Fish ecologists from Department of Environment, Land, Water and Planning’s Arthur Rylah Institute made the discoveries during surveys for the Victorian Environmental Flow Monitoring and Assessment Program.
Wimmera Catchment Management chief executive David Brennan said the results reinforced the positive outcomes good river flows and habitat could achieve.
“People who have lived along these waterways for decades speak fondly of the fish populations, and thanks to water for the environment and improved seasonal conditions, we are seeing fish species return,” he said.
“The community will be particularly excited about the blackfish discovery.
“We are seeing significant environmental gains in Mackenzie River and Burnt Creek systems.
“During the past couple of years we have seen the Peron’s tree frog populating the entire Burnt Creek system and we are now starting to see fish make their way along Burnt Creek and Mackenzie River.
“Over the years, drought conditions and other demands for water meant these waterways used to only receive a fraction of the water they needed to support vibrant and diverse fish populations.
“We are very excited about these results. They indicate that waterway health in these waterways has turned a corner.”
Mr Brennan said having Arthur Rylah Institute undertake research in the region was vital in gaining a better understanding of the impact of environmental flows.
“It also helps us improve timing and delivery of these flows to achieve the best results,” he said.
Fish ecologist Joanne Sharley from the institute said exciting findings showing the condition of these waterways were continuing on the right trajectory.
“The most pleasing outcomes are related to southern pygmy perch, a small-bodied species in decline across much of their natural range in Australia,” she said.
“This species accounted for most of the fish caught.
“The monitoring shows they are successfully breeding in both the Mackenzie River and Burnt Creek and extending their range.
“Their greatest numbers were found to be where aquatic plants were abundant, highlighting the value of habitat for these fish to breed and avoid predators.”
Mr Brennan said latest results were encouraging and provided a clear indication that human intervention could have beneficial as well as adverse effects on waterways.
“It shows that if we didn’t have the use of environmental water, Mackenzie and Burnt would have similar results to upper levels of the Wimmera River, which has no access to such a resource,” he said.
“What we’re finding is that we are creating a connection between the Wimmera River and the Grampians and it’s that connection we would like see go further upstream and downstream in the Wimmera River. But it’s all about baby steps. There are different circumstances in different areas of the river system. In the upper river we can’t manipulate circumstances with environmental water, so that means working with communities on other measures. It’s all about getting the balance right.”
• Environmental water releases in Mackenzie River and Burnt Creek are a priority as part of the Victorian Environmental Water Holder’s Seasonal Watering Plan 2017-18, which aims to improve river and wetland health across the state. Wimmera CMA has released its planned flows for summer online at www.wcma.vic.gov.au which it adjusts depending on weather conditions.