Controlling invasive fish species in Australia requires a combination of strategies tailored to specific species and environments. Here are some of the most effective methods currently employed:
1. Preventive Measures
- Exclusion Screens: These are installed in waterways and irrigation channels to prevent the movement of invasive fish, particularly tilapia. Screens can stop adult fish as well as their eggs and larvae, minimizing the risk of spreading into non-infested areas[1].
- Early Detection: Implementing monitoring systems to identify new populations of invasive species promptly can help manage their spread before they establish themselves.
2. Physical Removal Techniques
- Netting: Techniques such as gill and seine netting are effective for removing substantial numbers of invasive fish from small, enclosed water bodies. This method is relatively cost-effective and can be conducted by community groups, though it requires regular monitoring to avoid catching native species[1].
- Electrofishing: This method involves using electrical currents to stun fish temporarily, making them easier to capture. While effective in small impoundments, it requires trained personnel due to safety concerns[1].
3. Chemical Control
- Poisoning: The application of poisons like rotenone can be used for targeted eradication of invasive fish populations. However, this method is non-selective and can harm native species, necessitating careful planning and execution[1][5]. It is often used in conjunction with other methods for better effectiveness.
4. Biological Control
- Introducing Natural Predators: In some cases, introducing native predators (e.g., barramundi) can help control juvenile populations of invasive fish while other methods target larger individuals. This approach aims to balance the ecosystem without causing further harm[1].
5. Integrated Management Approaches
- Combining Methods: Employing multiple control strategies simultaneously—such as netting followed by electrofishing—has shown promise in increasing the effectiveness of removal efforts[1]. This integrated approach allows for more comprehensive management of invasive populations.
- Community Engagement: Involving local communities in monitoring and control efforts enhances effectiveness and fosters stewardship of aquatic ecosystems[2].
6. Strategic Planning and Policy Support
- National Strategies: The Queensland Invasive Plants and Animals Strategy emphasizes risk-based prevention and early intervention as cost-effective approaches to managing invasive species[2]. Coordinated efforts across different levels of government and community stakeholders are essential for long-term success.
- Research and Funding: Increased funding for research into invasive species management tools and strategies is crucial. This includes developing new technologies for detection and removal, as well as understanding the ecological impacts of invasive species on native fish populations[3][4].
By implementing these methods in a coordinated manner, Australia can better manage its invasive fish species, protecting its unique freshwater ecosystems from further decline.
Sources
[1] Tilapia control methods and their effectiveness – PestSmart https://pestsmart.org.au/toolkit-resource/tilapia-control-methods-and-their-effectiveness/
[2] Queensland Invasive Plants and Animals Strategy 2025–2030 https://www.daf.qld.gov.au/business-priorities/biosecurity/policy-legislation-regulation/queensland-invasive-plants-animals-strategy
[3] ‘Ring the alarm bells’: Study finds 35 fish species should be added to threatened species list https://www.abc.net.au/news/science/2024-11-15/freshwater-fish-survey-calls-for-35-new-threatened-listings/104597410
[4] Troubled waters: Australia’s freshwater fish are facing extinction – Australian Geographic https://www.australiangeographic.com.au/news/2024/11/australian-endangered-freshwater-fish/
[5] [PDF] Invasive Species in Australia https://www.agriculture.gov.au/sites/default/files/documents/invasive.pdf
[6] Troubled waters: how to stop Australia’s freshwater fish species from … https://theconversation.com/troubled-waters-how-to-stop-australias-freshwater-fish-species-from-going-extinct-242950
[7] A strategy for dealing with invasive species in Australia https://invasives.org.au/our-work/feral-animals/strategy-invasive-species-australia/
[8] Preventing extinctions of Australian freshwater fishes: A national assessment | Biodiversity Council Australia https://biodiversitycouncil.org.au/resources/factsheet-preventing-extinctions-of-australian-freshwater-fishes
