The Gulf of Maine Research Institute (GMRI) in collaboration with the Island institute and the Midcoast Fishermen’s Association (MFA) has just completed research confirming that fishing gear modifications by the MFA improve trawl selectivity and reduce the capture of non-commercial fish.
“In 2007 fishermen from Port Clyde formed the MFA with a goal to restore groundfish stocks, reduce environmental impact and sell high quality seafood to local consumers,” says Steve Eayrs, gear technologist with the research institute. “While the MFA have for some time been using modified fishing gear to reduce catches of non-commercial fish, called bycatch, until now there has been no attempt to independently measure the efficacy of these modifications.”
Last summer GMRI researchers spent nearly two weeks onboard the fishing vessel, Skipper, owned and operated by Glen Libby, chairman of the MFA. During this time the codend of a fish trawl-a netting bag that accumulates and retains fish that enter the trawl-was modified and tested under controlled scientific conditions.
The goal was to measure differences in the commercial catch and bycatch between a traditional codend and two modified codends. The traditional codend was constructed from diamond-shaped netting with a mesh size of 6.5 inches. Catches from this codend were compared to two codends constructed from square-mesh netting, one with a mesh size of 6.5 inches and another with 7.0 inches netting.
A fine mesh bag was placed over each codend net to capture all fish that would normally escape. “In this way we could quantify and compare fish escapement between codends,” said Eayrs. “The thought was that both the square meshes and the larger opening of the 7.0 inch mesh codend would have a higher conservation value and allow more bycatch to escape.
According to the data, the 6.5-inch diamond-mesh codend retained up to 72 percent of bycatch and less than 69 percent of legal-sized flounder.
In contrast the square-mesh codends retained less than 34 percent of bycatch and at the same time also retained 82 percent of legal-sized flounder.
“Clearly using square-mesh codends by the MFA is a step in the right direction” said Eayrs. “Not only do they retain substantially less non-commercial targeted fish than the diamond-mesh codends, but they also retain more commercial fish.”
“Many fishermen from Port Clyde are already using square-mesh codends and the results of this study confirm that it is the right choice,” said Libby. “This work will add credibility to our claims and will only strengthen our marketing efforts.
The MFA will continue its collaborative research with Gulf of Maine Research Institute and the Island Institute next summer to reduce fuel consumption and further reduce bycatch.
“This work was critical to the MFA, and without this collaborative research we would not have been able to take our ideas and put them to the test” concluded Libby. The full results of this research are expected to be published in March and will also be highlighted at the 2009 Maine Fishermen’s Forum.