
Streambank Erosion.
Streambank erosion, caused by poor riparian vegetation and heavy rainfall, is a source of sediment flowing to the Great Barrier Reef.
Healthy waterways underpin our lifestyles and livelihoods. When waterways thrive, so do we.
Pest fish are invasive species that can harm native aquatic ecosystems by introducing diseases, competing for resources, preying on native species, or altering habitats.
Pest fish are almost impossible to eradicate from our natural waterways once they’re established, which means that our best strategy is to prevent them from being introduced in the first place.
The Wet Tropics region in Queensland has the highest diversity of freshwater fish species anywhere in Australia. Assessments have shown that fish populations in the rivers of the Wet Tropics are generally in good condition, although the Barron River is the most impacted by invasive fish species.
Some of the pest fish species that have already become established in the Wet Tropics, include tilapia, platys, guppies and swordtails.
There are two types of pest fish:
• Exotic pest fish – introduced from overseas
• Translocated pest fish – introduced Australian species that are not naturally occurring in that specific location
Tilapia: A Noxious Exotic Species
Tilapia is a particularly noxious species because it can reproduce so prolifically that it displaces whole fish communities. Originating from Africa and the Middle East, Tilapia was first reported in the Wet Tropics in the 1970s in the Barron River and there are now two species that have become naturalised in this catchment – the Mozambique Tilapia and the Spotted Tilapia.
Translocated Fish: Native But Not Always Nice
Translocated fish are fish that have been moved from one area to another by human intervention, either intentionally or accidentally. Translocated fish species may be native to Australia but if they are moved into a natural waterway outside of where they occur naturally, then they can dramatically upset the balance of the local ecosystem.
A good example is Lake Eacham, a crater lake on the Atherton tablelands west of Cairns, which was historically home to a small number of native fish including the Lake Eacham rainbowfish. However, the introduction of larger native predatory fish such as mouth mighty and archer fish, and other species of rainbowfish saw the endemic Lake Eacham rainbowfish driven from the lake through predation and hybridisation.
What Can We Do?
We can’t eradicate pest fish species once they’re established but we can take measures to prevent further exotic or translocated species from being introduced. Community awareness and education about the best ways to dispose of aquarium or pet fish is our best strategy.
Unwanted fish should never be released into natural waterways or flushed down the toilet. Instead, they should be returned to a pet shop, given to a new home with friends or family, or humanely euthanised.
Streambank erosion, caused by poor riparian vegetation and heavy rainfall, is a source of sediment flowing to the Great Barrier Reef.
A mass die off of fish can be caused by a number of different factors and they're a reminder of the delicate balance of healthy waterways.
Nutrients, pesticides and sediment runoff from land based activities cause poor water quality for 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.