Greening Australia and the Harvey River Restoration Taskforce commissioned Murdoch University to conduct the survey as part of the ‘Marron, more than a meal – revive our rivers’ project.
The work was made possible thanks to funding from the Alcoa Foundation through its Three Rivers One Estuary partnership with Greening Australia, and from a State Government Royalties for Regions grant to improve the health of the Peel-Harvey Estuary and rivers, overseen and delivered by the Peel-Harvey Catchment Council.
“This project has provided exciting new baseline data about the aquatic species in the lower Harvey River,” said Dr Stephen Beatty from Murdoch University’s Centre for Sustainable Aquatic Ecosystems.
“If the key findings are implemented, we may have a long-term solution to the restoration of the river, and simultaneously future proof the native freshwater fish and crayfish found there.”
Two surveys were conducted, six months apart, at four reference non-restored sites and a restored site.
Researchers found the greatest diversity of fish at the restored site, where rehabilitation works have been undertaken over the past 10 years. Carter’s Freshwater Mussel also appeared in the highest densities there, which is a key indicator of water quality.
The rehabilitated area was also the only site where marron and gilgies, native freshwater crayfish species, were recorded.
“The results show that marron are more likely found in shaded parts of the waterway with a good variety of instream habitats, including deeper, cooler pools of water. Not surprising, since marron are sensitive to higher water temperatures,” said Dr Christine Allen of Greening Australia.
“As climate change drives increases in temperature and decreases in rainfall, we must act now to give marron and other aquatic fauna a fighting chance. We know what works. We can restore vegetation along the riverbanks to provide shade, we can add instream logs and rocks for habitat, and we can add deeper pools back into the waterway.”
The third largest freshwater crayfish in the world, marron is endemic to the global biodiversity hotspot of Southwest Western Australia. Sustainably consumed by Aboriginal people for generations, large-scale modification of local waterways has seen wild populations of this tasty native crustacean decline, resulting in heavy restrictions on recreational fishing.
Given the popularity of marron among locals, engaging community has been a key part of the project, with residents and school students from surrounding neighbourhoods taking part in citizen science days with the Murdoch University team.
“It was great to offer locals an opportunity to be involved and see what a diversity of life we have in this waterway in our own backyard. I worry sometimes that the Harvey River is perceived as just a public drain,” said Jennifer Stringer, Chairperson of the Harvey River Restoration Taskforce.
“It’s true that channelising waterways in this region has contributed to declines in native aquatic ecosystems. But that’s not the end of the story – the results from the rehabilitated site show that, if we put in some effort, we can improve habitat opportunities for those native species still hanging in there.”
“However, we also recognise that successful rehabilitation relies heavily on maintaining broader catchment-scale processes, such as ensuring there is enough flow in the river to connect the various habitats that native fish and crayfish utilise throughout their respective lifecycles. As such, it’s vital that we consider habitat improvement from a broader perspective.”
Decision makers linked to management of the Harvey River met in Waroona last week to discuss the survey report and next steps.
Greening Australia and the Harvey River Restoration Taskforce are encouraging local communities, schools and businesses not to wait to be part of the solution.
“There needs to be a coordinated effort to fix up the Harvey River for iconic species like the marron, and it will take all of us working together,” said Dr Allen. “We would really encourage local businesses and communities to get behind the project.”
Ms Stringer said: “We could use support in so many ways – from permitting revegetation works on your property or volunteering your group for a day out in the field, to raising funds for seedlings, logs and rocks.
“We’re excited for what the future of the Harvey River and marron could be if everyone rolls up their sleeves.”
For more information about this project, please send us an online query.