This NIWA-led, three-year project aims to develop trawl gear that will minimise the bycatch of undersize fish and unwanted species. Specialised, size-selective trawl nets coupled with video camera capabilities can ensure that only desired species and sizes are retained.
Many fisheries encounter multiple species of different sizes and shapes which can make selective, targeted fishing difficult. Unintended bycatch of undersize fish and unwanted species can have a major impact on the sustainability of fish stocks, ecosystem health and public perceptions of the commercial fishing industry.
This MBIE-funded project aims to develop high technology tools to minimise the bycatch of undersize fish and unwanted species in trawls. The team is building on highly selective trawl gears already developed by New Zealand inshore fishers. By combining them with state-of-the-art underwater video cameras, computer vision and underwater engineering technology, real-time “eyes” and decision-making by the skipper are enabled during trawling. A drafting gate triggered from the vessel guides fish into a novel, highly selective rigid codend or releases them alive at depth.
This ensures that only the desired species and sizes are brought to the surface and kept, providing fishers with unprecedented control over what is retained in their nets. Releasing unwanted catch at depth, including juveniles, will maximise their survival and improve the overall productivity and economic value of fish stocks.
The team is also developing computer vision methods to automate the fish identification and size measurement which could ultimately also allow the underwater selection process to be automated.
Working closely with local fishers and overseas experts, researchers will ensure designs are practical and robust for commercial fishing operations.