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Healthy waterways underpin our lifestyles and livelihoods. When waterways thrive, so do we.
Fishing isn’t allowed in the deep volcanic waters of forest-fringed Lake Barrine, but if you visit on a Sunday, you might just see a group of spear fishers descending into the water…
These spearos are volunteers in a tilapia culling program that’s been running for more than a decade through the Queensland Parks and Wildlife Service and Cairns Underwater Association. Its focus is on limiting the ecological impact of Queensland’s most problematic aquatic pest species.
The black mangrove cichlid, or spotted tilapia, isn’t native to Australia. Its first confirmed sighting was in Lake Barrine was in 2007. Well-equipped to invade and dominate aquatic habitats – with its simple food needs, its ability to thrive in poor water conditions and its resistance to disease – this species aggressively out-competes natives for food and space, leading to declines in biodiversity.
Here to stay
Like so many other invasive species, now that tilapia is established in Australia it’s proving impossible to eradicate. But in an enclosed water body like Lake Barrine, numbers can be controlled to some degree with intensive long-term fishing.
Electrofishing, line fishing, gill netting, fish traps and artificial egg-laying strata have all been trialled over the years. None were successful in significantly or effectively reducing the population. Then along came the idea of spear-fishing…
John Doherty from the Queensland Parks and Wildlife Service says managing any kind of pest species is time intensive.
“Parks staff were initially used but you need experienced spearers to get good numbers,” he says. “That’s why we are so pleased about the ongoing involvement of the Cairns Underwater Association. They have the gear and the experience, and they bring in thousands of fish each session. Without them the program would be dead in the water.”
Ant Judge coordinates the spear fishers from the Cairns Underwater Association and says being in the water is a big part of his lifestyle.
“I love it. I spend a heap of time diving in Barrine and Eacham,’’ he says. “Waterways are integral to living in the region and it’s important to me that they’re being looked after.
“We can immediately see the impacts of culling. When the big breeders are flushed out from their nesting areas, I’ve seen native species move in straight away to eat the eggs.”
The Underwater Association is keen to expand the number of spear fishers participating, and is thrilled that a women’s group, Girls Who Spearfish, has come on board.
“With the addition of this group of talented spear fishers, we can increase cull numbers significantly,” Ant says.
The club runs identification training before culling events, so there is no bycatch. Competent spear fishers wanting to get involved are encouraged to contact the club.
True locals
Not far away, Lake Eacham was home to three types of native fish until their numbers declined with the introduction of other species. While native to Australia, these new species weren’t native to the lake and they outcompeted the original habitants. By 1987 there was only one ‘true local’ remaining, and the Lake Eacham Rainbowfish has disappeared from the lake.
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Road upgrades to tree planting and improvements to sewers, local Councils are leading the way
More than 200 species of jellyfish are found along the Great Barrier Reef.
Martine joined the Wet Tropics Waterways team as a Science Technical Officer in early 2024 and is keen to apply her experience in statistical programming and database development for the Report Card.
She is an environmental scientist and ecologist and has worked on water quality and aquatic ecology projects as a consultant and in private industry for over 20 years.
Martine has many hobbies and is currently dabbling in horticulture.
With a degree in marine biology and zoology from JCU, Phil has had a diverse career covering research in fisheries biology, 15 years in reef tourism and 13 years with GBRMPA delivering engagement and partnerships programs. Since 2019 he has been self-employed and operates as a consultant to a range of stakeholders on waterway related programs.
He is a keen fisherman.
James joined Wet Tropics Waterways as Executive Officer in 2021 and is passionate about working with stakeholders to communicate the value of our unique waterways. His role involves facilitating and coordinating our partnership program, growing our network and investment into the report card program, and science communication. James oversaw the 2022 Innovations in Waterway Health Forum, and hosted season four of the Reef and Rivers podcast.
James is an ecologist and has previously worked on wetland management in the Murray Darling basin, fish passage in Mackay, and aquatic research in the Wet Tropics.
Outside of work you’ll find him in a local waterway with a mask and snorkel, or hiking or biking around our beautiful region.
Richard has been the Science Technical Officer for Wet Tropics Waterways since 2016. His role involves producing the annual results for the waterway health assessment of the wet tropics region using data from a wide range of sources, to present as scores and grades, as well as developing new indicators to address knowledge and monitoring gaps. He works in collaboration with technical staff at other regional report cards.
Richard has a background in freshwater ecology research projects and environmental assessments with CSIRO, University of Queensland, Queensland Government and as a consultant. For a long time he’s been interested in freshwater aquaculture and continues this interest through farming freshwater crayfish, alongside other farming activities.