AMC revolutionises the prawn fishing industry

A new research project by the Australian Maritime College is poised to revolutionise the prawn fishing industry.

The project, which uses underwater lights to deter fish from prawn nets, has just yielded early results that include:

• 30 percent reduction in fish bycatch;
• 10 percent increase in prawn catch;
• reduction in fuel usage meaning lower operating costs as a result of reduced weight in the net.

The project has presented a more successful picture than first anticipated, according to research leader David Maynard from the Australian Maritime College's National Centre for Marine Conservation and Resource Sustainability.

"The United Nations estimates annual fish discard is 7.3 million tonnes a year. Tropical shrimp trawling is responsible for a quarter of that. We've just found a way to reduce discards by 30 percent. For every kilo of prawns there are between three and 20 kilos of fish discarded at sea. If this was adopted throughout the world we'd make massive inroads into bycatch reduction, sustainability of non-target species and sustainability of juvenile commercial species that cohabit with prawns. Potentially our method could reduce global bycatch by more than half a million tonnes per year," Mr Maynard said.

He said the new approach to an old problem had been the key.

"The way we're looking at this issue is totally new,'' he said. "What's been done in the past is to look at ways to reduce bycatch once the fish are in the back of the net."

Mr Maynard said the problem remained in the issue of post escape mortality or, put simply, what happened to fish once they escaped.

"All the effort in all state departments and federal research and overseas has gone into tackling the issue of bycatch in the back of the trawl net. They're dealing with the issue once it's happened. Overall there's about a 30 percent reduction using existing bycatch reduction tools. But these fish that escape, you don't know if they survive. What we don't know is the post escape mortality. The fisheries managers can feel good about these nets coming up with less fish in them but they don't know if they actually achieved anything," he said.

"So what did we do? We received funding from the Dept. Agriculture Fisheries and Forestry and we put lights along the trawl nets. The lights trigger a flight response in fish, and 30 percent of the fish are able to avoid entering the trawl net. And because these fish didn't enter the trawl the issue of post-escape mortality doesn't exist.

"What the early figures are showing is that as well as the bycatch reduction we're finding an increase in the prawn catch by 10 percent," he said.

The decrease in bycatch means boats will have reduced fuel costs as they are trawling with less weight to tow.

Mr Maynard also believed prawn fishermen could ultimately reduce their number of fishing days due to the catch increases.

Conducted in the Torres Strait fisheries during June, the latest round of field work saw AMC Fisheries graduates working on the prawn trawl charter. The latest results, including bycatch species, are still being collated but Mr Maynard said the early indicators were very positive.

"We believe we're doing something really positive here, " he said.

Information released by:
Media Office, Australian Maritime College
Patrick Cranny
Phone: +61 3 6335 4484
Mobile: 0429 117 000
Email: p.cranny@amc.edu.au

David Maynard

Example of an average fish catch

AMC student fitting light to trawl net

Prawn catch increase of 10%