A new aquaculture project to grow black bream for release into the Murray River is hoping to help restore the health of the local waterway.
The Mandurah Mail recently shone a spotlight on the health of the rivers in the Peel region, which continues to decline.
Assessments have revealed, of almost 4000 kilometres of waterways throughout the Swan Coastal Plain, only about 1 per cent is in "pristine condition".
In an effort to uncover why local waterways are not in the condition they should be, over the coming weeks the Mandurah Mail will be interviewing environmental experts to gauge the health of local rivers and report on the research being conducted and initiatives in place to help restore them.
After speaking with leaders from the Peel-Harvey Catchment Council (PHCC), who sounded grave concerns about the condition of Mandurah's waterways, the series continues with the first of a number of initiatives to help improve the health of local rivers.
Partnering with John Tonkin College and Murdoch University, PHCC recently launched a new aquaculture project to grow black bream for release into the Murray River.
Black bream are native to Western Australia, are among the most important recreational fin fish species found and play an important role in the Peel-Harvey estuary ecosystem.
Black bream complete their life cycle in the waters in which they're born, therefore those born in the Murray River are entirely dependent on the river and the Peel-Harvey estuary to provide suitable habitat, including water quality and food, from birth to death.
However, as a result of the declining health of the Murray River, the survival of black bream is under threat.
The survival of black bream to adulthood has been has been unsuccessful for much of the past decade, which, in combination with recurring fish kills, has decimated the stock.
The aquaculture project aims to enhance the stocks of black bream by protecting the fish from these threats by growing them in captivity during the first five months of their lives before release into the wild.
One of the most exciting aspects of this project is working with John Tonkin College students who are our future scientists and leaders.PHCC chair Caroline Knight
Since March, a room at John Tonkin College's Tindale Street campus has been transformed into an aquaculture laboratory for specialist surf science program students to start building a food web.
Under the supervision of teachers Barbara Sing and Kim Davies, the students have been growing algae to use as food to grow microscopic aquatic animals called rotifers, which will in turn be used as diet for black bream during their early life stages.
In May, between 50 and 100 adult black bream were collected from the Peel-Harvey estuary by Murdoch University scientists to be used for brood stock, which will be conditioned until the end of July before being induced to spawn.
John Tonkin College students will care for the resultant bream larvae and grow them on a diet of rotifers for about a month before swapping their diet to brine shrimp, which they will also grow on site.
At the end of the 2019 school year, a sample of the bream will be checked to ensure they are disease-free before approximately 5000 juvenile black bream are released into the Murray River.
With the project funded by a Royalties for Regions grant until 2020 as part of the 'Recreational Fishing for the Future'WA government election commitment, the process will be repeated until the end of next year.
Read more on this series: Spotlight on river health: Condition of Mandurah's waterways continue to decline
PHCC science and waterways program manager Dr Steve Fisher said his team had big plans for the future of the program to continue to improve the health of the Peel-Harvey estuary.
"We hope to extend the aquaculture program beyond 2020 and to also engage with recreational fishers as citizen scientists to help us monitor the survival rate of the aquacultured bream," he said.
"Fishers would provide us with the skeletons and heads of adult bream they take from the estuary, in particular the Murray River, for students and researchers to examine the earstones, or otoliths, removed from inside the fish's head to establish the age of the fish and whether or not it came from the aquaculture program.
"Community members are distraught when fish kills occur, especially residents around the estuarine parts of the Murray River and Serpentine Rivers.
"Involving the community in the aquaculture and citizen science monitoring program recognises and acts on their concern."
PHCC chair Cr Caroline Knight said it was particularly important to have high school students take part in the project.
"One of the most exciting aspects of this project is working with John Tonkin College students who are our future scientists and leaders," she said.
"Not only are they learning new skills and discipline in aquaculture, they are also getting hands on experience in the biology of black bream and the challenges the species face to survive in our changing environment.
"This project will raise their awareness of the fragility of the health of the Peel-Harvey estuary, in particular the lower reaches of the Murray river, and the importance of good stewardship of the estuary and catchment in the long-term protection of our natural environment."
Murdoch University centre for sustainable aquatic ecosystems researcher Dr Alan Cottingham and Dr Ben Roennfeldt are contracted by the PHCC to oversee the aquaculture program.
A catastrophic fish kill could see the loss of the species from the Murray River for years.Murdoch University centre for sustainable aquatic ecosystems researcher Dr Alan Cottingham
Dr Cottingham said the project would play an important role in not only helping to restore local rivers but also black bream stock throughout Western Australia.
"The current stock enhancement project is playing a vital role in sustaining black bream in the Peel-Harvey estuary, which hosts the second most important recreational black bream fishery in the state," he said.
"Initiatives, such as these, are coming increasingly important as climate change and other human-induced impacts have deleterious effects on these systems".
Dr Cottingham said his research had shown the recruitment and breeding of adult black bream had not been successful for much of the last 10 years.
"The reasons for this poor recruitment are unclear, but possible causes include unsuitable water quality during spawning or loss of adult females capable of breeding from recurring fish kills over the past decade or so," he said.
"A catastrophic fish kill could see the loss of the species from the Murray River for years.
"With the aquaculture program, we can overcome all of the issues the black bream are facing in nature and have much higher survival rates.
"Following this two year pilot study, we envision that we will continue collaborations with John Tonkin College to be able to keep this project going."