Background/Aims
The impacts of trawl fishing on sawfish populations are largely unknown however sawfish have a poor ability to escape trawl nets due to their rostrums being entangled in nets. The aim of this project was to identify practical, cost- effective mitigation solutions to reduce the impacts of commercial prawn trawl fishing on endangered or migratory species of sawfish in the NPF. The Turtle Excluder Device (TED) area of the net and the TED escape flaps in the net have been identified as areas of high entanglement of sawfish (Laird et al 2019). Net modifications in these areas pose potential for increasing sawfish escapement. The intended project outcomes are improved escapement, reduced interaction rates, improved knowledge, and improved sustainability of sawfish populations.
Methods
This industry-driven, industry-led two year project trialled several new fishing gear innovations aimed at reducing sawfish interactions, collated data pertaining to interactions with existing trawl gear, investigated alternative net mesh types with potential to reduce sawfish entanglements, and collected and analysed data on interaction rates during sea trials using independent scientific observers and underwater cameras. Gear mitigation options trialled included small bar spaced Turtle Excluder Devices (TEDs), magnet and ruby net mesh, and ‘Flo-Mo’ composite material inserted in TED flaps. All trials were conducted as part of normal commercial fishing operations during the NPF 2023 banana prawn and 2024 tiger prawn fishing seasons.
Results
Small bar spacing TEDs showed positive signs for reducing interactions with sawfish and other large bycatch species. Grey Magnet mesh in the throat of the net had zero sawfish interactions, suggesting this material may be effective for reducing entanglements. The composite Flo-Mo material is worthy of further investigation given no sawfish interactions were observed during this trial.
Conclusions:
Several gear mitigation options with potential to reduce sawfish interactions in the NPF were identified in this project. These will be considered at the NPF Sawfish Mitigation Workshop scheduled for November 2025, the outputs of which will inform the development of the NPF Sawfish Strategy (2026). This project demonstrated the benefits of industry-led, collaborative research aimed at achieving positive environmental outcomes for TEP species.