Coorong fishers are reporting signs of the slow recovery to parts of the iconic wetland thanks largely to the delivery of water for the environment.
Despite dry conditions across the Murray-Darling Basin over the last four years, water for the environment has been delivered in small volumes via the barrages and fishways which has been keeping parts of the Coorong functioning.
The much-needed fresh water is helping to lower salinity in the north lagoon of the Coorong, which two local fishermen say is benefitting native fish populations.
Glen Hill, of Coorong Wild Seafood, said bigger fish such as flounder and black bream which are estuary dependent, are building in numbers which is proof that the environmental water releases are working.
”I often like to find out what the fish are eating and can attribute healthy looking fish to the food available,” Glen said.
“This is due to the response of the bottom end of the food chain to the environmental flows released into the Coorong.
“It’s positive to see, however it’s only half the story as there are not enough environmental flows to see the same response in the South Lagoon.”
Garry Hera-Singh of Meningie, has been a commercial fisher for 38 years and has observed increased abundance and diversity of the many fish species in the Coorong over the last decade.
“Increased productivity has been purely driven by strategic and managed annual releases of environmental water through the barrage network,” Garry said.
“While this is a fantastic outcome, more water for the environment is needed to be delivered to the Coorong to build a higher level of resilience within the aquatic ecology for the next drought, and to buffer the impacts of long term climate change facing the region.
“Specifically, more river flow is needed to address the degradation of habitat issues plaguing the South Lagoon of the Coorong.
“Once upon a time (pre white man) this region was a major fish habitat and nursery area.”
Coorong, Lower Lakes and Murray Mouth Program Leader Adrienne Rumbelow explained that during summer and autumn, salinity in the South Lagoon now often exceeds 100 parts per thousand (three times the salinity of seawater) and is largely uninhabitable for most native fish.
“This is not a natural condition in the South Lagoon. High flows from the River Murray are needed to dilute and flush this salt from the system, yet this critical process has been happening much less frequently in recent decades,” Adrienne said.
“River regulation and development have resulted in significant disruption to natural flows to the Coorong. Many of our rivers and wetlands have been modified as the population has grown to provide water for towns, industry and food production.
“In some rivers, up to half of the water that would have naturally flowed in them is removed each year for critical human water needs, irrigation and industry.
“This means that end of system flows to the Coorong are now just a small fraction of what would have occurred naturally.
Adrienne explained that water for the environment is water allocated and managed to improve the health of rivers, wetlands and floodplains across the Murray-Darling Basin.
“Water for the environment allows us to actively manage how some water flows through these waterways and reintroduce a more natural flow regime - these flows are what we call ‘water for the environment’,” Adrienne said.
“Much of this water has been provided through the return flows of water delivered by the Commonwealth Environmental Water Holder to achieve environmental benefits in river channels and floodplains in New South Wales, Victoria and elsewhere in South Australia.
“The return flows from these environmental waterings have made their way down to the Lower Lakes and allowed at least some fresh water to flow from the River Murray to the Coorong at all times. As a result of the provision of environmental water, there has been almost 11 years of continuous connectivity between the freshwater river environment and the sea.
“Without water for the environment, there would have been no freshwater flow to the Coorong between January 2018 to August 2020 and the ecology of the Coorong would have collapsed.
“These improvements have been most evident since Basin Plan implementation began in 2012 and it’s rewarding to know the changes have been noticed and appreciated by the Coorong’s commercial fishing industry.”
Project Coorong’s Healthy Coorong, Healthy Basin initiative is also currently investigating possible long-term management measures to improve the health of the Coorong South Lagoon to include, amongst other things, thriving fish communities.