Increasing Selectivity of Shrimp Gear

Yankee Ingenuity May Make Shrimp Fishing More Selective

by Ken La Valley
Extension Specialist, UNH Cooperative Extension/ NH Sea Grant
January 24, 2005

Boothbay Harbor, ME - Shrimp fishermen will be able to target the lowest count, best priced shrimp while limiting fishermen impact on the upcoming year class, if Kelo Pinkham has anything to do with it. Kelo, in a cooperative research effort with a team from the Maine Department of Marine Resources (MEDMR), has come up with what looks like more selective shrimp gear by modifying the Nordmore grate system.

Kelo Pinkham, Captain of the F/V Jeanne C, has spent the best part of thirty years fishing out of Boothbay harbor, Maine .  At the age of 11, he began weekend duty working summers, weekends and school vacations as a deckhand aboard the F/V Gladys B . Part-time shrimp and groundfishing continued up until he graduated from high school when he began fishing full-time.  He recalls the booming groundfishery of the late 70's, when Boothbay fishermen made their money trawling rather than lobstering.  "For twenty years, fisherman out of Boothbay never fished more than twenty miles from the harbor. Just about ten years ago we started needing to go twenty-five to thirty miles just to find a fish."

It was at this point that Kelo needed to make a decision, "I had to either buy a 50-ft boat and go fishing for four or more days, or go the lure of lobstering". He chose the latter.  "Being home with my kids, even if at 8 or 9:00 pm every night, was more important." It was also around this time that he purchased the F/V Jeanne C.  For quite some time he was the smallest Maine full time dragger fisherman, a fact he takes particular pride in.

Just about four years ago, Kelo first became interested in improving the size selectivity of shrimp trawl gear.  An abundance of small shrimp not desirable to local processors and important to the future of the shrimp fishery, were being landed in high numbers.  Interested in increasing the efficiency of his gear, Kelo was introduced to Dan Schick of the MEDMR, who at the time was evaluating a double grate design with a Kennebunkport , ME fisherman.

The strategy of the double grate design was to eliminate groundfish and large shrimp from the cod-end with the first grate (1" bar spacing), and then reduce the catch of undersized shrimp with a second smaller (7/16") bar space grate.  During the selection process, non-target species are directed toward an escape panel placed just ahead of the grate in the extension piece.

Not being able to obtain a special permit for the fine mesh twine used in the second funnel of the double grate, Kelo decided to add a small bar space section to the top of the initial grate.  With this design, the second grate and fine mesh funnel were no longer necessary, and the benefit of reducing the catch of small shrimp remained.  Kelo recalls that, in addition to the fine mesh problem, he as well as other fishermen "couldn't imagine getting two grates around the net real.with doors banging around and two grates, there's twice as much chance to have something go wrong!"

Kelo used the single grate design for three years, when Lessie White, of the MEDMR, approached him regarding his gear innovations.  Kelo's shrimp processor had told Lessie that he was impressed by the size and quality of the shrimp Kelo had been landing.  At about the same time, Kelo attended an information workshop by the Gulf of Maine Research Institute about getting cooperative research funding through the Northeast Consortium.  Newly interested by the prospects of more organized research, he went back to Dan Schick and together they submitted a proposal to the Northeast Consortium in 2002 and got funded that same year.

Together, Kelo and the MEDMR team studied the one piece separator grate that they had designed.  The experimental grate design combined the proven ability of the double Nordmore grate system to release small shrimp with the ease of handling just one grate in the net.  The results from the 2002 work were not as good as he had observed with his previous design.  He thought the diamond mesh cod end and lengthener (selected by MEDMR because it was the world wide standard) in conjunction with the 7/16" he had used for three years previous, reduced the size selectivity of the grate.

In 2003, the cooperative research team submitted another proposal to the Northeast Consortium.  This time the 7/16" bar spacing grate and a new nonparallel bar grate with a bar spacing tapering from 5/32" to 1/2" were tested, with the addition of a square mesh cod-end and/or lengthening piece.  They are now in data analysis mode, but preliminary looks at the data appear to reveal increased selectivity than was observed with the 2002 design.

Three years into grate research, Kelo is still enhancing the grate design.  He just never stops and is never satisfied with mediocre selectivity.  His goal is to reduce the catch of undersized shrimp by at least 80 percent and virtually eliminate the bycatch of groundfish species.

Currently, he is evaluating and making available to interested fishermen a third generation design through the same Northeast Consortium-funded project.  This time, the compound grate is hinged into three sections.  The top section is comprised of nonparallel spaced bars of 5/32" to 1/2" and the remaining length, made up of two hinged sections, has parallel spaced bars of approximately 3/4". The expectation is that small shrimp will pass through the small bar spacing at the top and exit the net through an escape panel and that the market-sized shrimp will pass through the larger bar spacing further along the grate and flow into the cod end.

Using a hinged design allows the grate to be longer than a typical grate without making it any more difficult to wrap the net around the reel on haul back.  This grate system not only has shrimp size selectivity benefits, but it significantly reduces the bycatch of several species of flatfish, cod, hake, herring and other commercially important groundfish.  In addition, the compound grate system can be used without the need for changes in the current shrimp fishery regulations.

For more information regarding this project, its preliminary results and additional cooperative fisheries research, visit the project information database.