Tor Bendiksen, owner of Reidar’s Manufacturing, Captain Mark Phillips, and Dr. Pingguo He of UMass Dartmouth hold four sections of helix twine joined to make a mesh. Bendiksen continues to design the right self-spreading net for East Coast fishermen. Phot
Self-spreading helix twine may improve efficiency, reduce bycatch, and give fishermen access to more fishing grounds.
Beginning in 2018, David Chosid of the Massachusetts Division of Marine Fisheries and Dr. Michael Pol tested a self-spreading off-bottom trawl (OBT) against the older design Ruhle trawl, which had become common in the groundfish bottom trawl industry. “At the time, the haddock resource was peaking, and the idea was to develop an off-bottom trawl that fisherman can use to target haddock better while avoiding or excluding Atlantic cod and other bycatch and possibly provide access to areas closed to bottom gear,” says Chosid. Results of the tests showed that even when making some bottom contact, the OBT could increase efficiency and reduce bycatch.
The large meshes at the mouth of the off-bottom trawl tested in 2018 appear as a multitude of lines wound onto the net reel. They are color-coded to indicate which part of the net they belong to. Photo by David Chosid
“Both nets are designed to catch haddock and not cod,” says Chosid. “The major difference is the OBT uses a helix twine developed by the he Hampiðjan Group in Iceland and is designed to be fished entirely off of the seafloor.” Chosid notes that the Swan Nets in Seattle has been building nets using helix twine since 2014. “They use them in the Bering Sea pollock and the West Coast hake fisheries,” says Chosid. “We wanted to find out how they would perform in the northeast U.S.”
Helix twine, developed by Hampiðjan Group in Iceland, creates a water flow that pushes it in one direction or another depending on the direction of the coil. Photo by David Chosid
Chosid, Dr. Pol of the Responsible Offshore Science Alliance, and their team made four multi-day trips aboard Captain Mark Phillips’ 73-foot trawler, the Illusion. “We tested two OBT trawls,” says Chosid. “The first trip was to tune the OBT 1 and the second trip was to compare its catches versus the Ruhle trawl. Then shortly after, we made two trips to tune and compare the OBT 2, which was much larger than the OBT 1.”
The team found the OBT 2 to be too large for the test locations and focused instead on the results from the OBT 1 testing. Chosid and Pol published their report in March of 2023.
“The helix twine is twine with another thread coiled around it,” says Chosid. “The coils go opposite ways on each side of the mesh, and these are big meshes, and the hydraulic forces while towing makes them spread apart.” According to Chosid and Pol’s report, 18mm helix twine is used in the front of the net on mesh sizes reducing from 150 to 64 inches. As a result, Chosid, Pol and company found that even with its larger opening, the OBT 1 net could be towed faster at the same RPMs as the Ruhle trawl, effectively increasing efficiency. “We were using Gull Wing doors,” says Chosid. “And the net mensuration technology we were using was a little outdated so that we could not see exactly what the opening of the net looked like.”
The off-bottom trawls being developed as a result of the UMass Dartmouth research are intended to fish close to the bottom for haddock and other species and use semi-pelagic doors, such as the NET Systems gull wing.
Chosid notes, however, that the OBT 1 net caught significantly less bycatch than the Ruhle trawl. “The only cod we caught, and it wasn’t much, we caught in the Ruhle trawl,” he says. “With other species like monkfish, the OBT 1 was catching much less compared to the Ruhle trawl and zero winter skate were caught in the OBT 1. And that was using a slightly smaller sized mesh on the OBT codend (5.1 inches versus the 6 inch codend meshes used in the Ruhle trawl)” which also revealed no differences in caught fish sizes between the two nets.
However, the team had trouble completely eliminating bottom contact. Their report notes that the OBT 1 net required frequent tuning and considerable attention to speed and wire length compared to the Ruhle trawl when trying to maintain the door spread and net height off bottom, noting that they relied heavily on the captain’s skill. “The frequency of adjustments was lessened with the addition of drop chains near the wing ends,” the report says. But it adds that “sensor data, underwater video footage, and post-drop chain shine revealed evidence of a footrope that was close to or touching bottom.” While the use of drop chains led to some bottom contact, the team believed it was substantially reduced compared to the Ruhle trawl and that complete reduction of bottom contact is possible with more practice.
“Our results demonstrate the benefits of fishing with a helix twine OBT, even over an established trawl net designed to reduce Atlantic cod catches, despite using a small codend mesh size. We are optimistic that further exploration with this and other OBT gears in various areas of Georges Bank and the Gulf of Maine, targeting species other than haddock, such as redfish, will yield more positive results.”
The exploration is continuing at Reidar’s Trawl Gear and Marine Supply in New Bedford, Massachusetts. Tor Bendiksen, owner of the business started by his father, helped design the OBT nets that Chosid tested, and they were both built at his shop. “We based the first nets on the Ruhle trawl,” says Bendiksen. “We added the helix and expanded the opening. Then we tried the bigger one that came from Hampiðjan, but we found that covered too much of the water column, so we’re making some adjustments, making it a little more compact. And we’re working on some other ideas, some are my designs, but we have a team and we’re combing our ideas for nets that can target fish higher in the water column, like redfish.”
Beniksen started his current project with the local seafood producer Blue Harvest but had to put it on ice after the Dutch private equity firm Bregal Partners acquired a controlling share of Blue Harvest and managed it into bankruptcy. “After the Canastra’s bought the Blue Harvest assets, they picked up the ball, and we started working on it again,” says Bendiksen.
“We want to make one that’s easier for our boats to handle so we can have a tool that can fish off bottom and get these going here on this coast,” says Bendiksen. One of the problems he and the new team are trying to solve is vessel design. “They’ve been doing this in Europe and Iceland—they can to this all day long. We have to work with vessels that weren’t designed for this. The pelagic trawlers in Europe and Alaska and those places have the net reels forward, so it’s easier to make adjustments and shift around the weights you need. Ours are still trawlers, with the net reel on the stern, so we’re working on the design to make it easier to handle.”
Pelagic trawlers often have net reels forward, which makes tuning the net a little easier, a challenge that Tor Bendiksen and the team he’s working with faces, is designing nets for New England trawlers that have the net reel on the stern. Photo by Chosid
Besides the Canastra family and Bendiksen, the School for Marine Science and Technology (SMAST) at the University of Massachusetts Dartmouth is also involved in the project. “We’re lucky to be working with Kevin Stokesbury at SMAST,” says Bendiksen, they’re getting some grant money to help fund a lot of this work. The commercial fishermen want to get this going because they know it’s what they’re going to need going into the future, especially with the redfish stocks up, as well as the haddock and pollock.”
A haul back from one of the 2018 test tows yielded exactly what the researchers were looking for clean haddock. Photo by David Chosid
While the New England fleet is behind the West Coast and European boats in adopting the Hampiðjan helix twine self-spreading nets, efforts by Bendiksen, the Canastras, SMAST and other members of the Massachusetts team are expected to produce a practical version of the gear by 2025. “If we can get it off bottom, it might open up some opportunities in those closed areas as well,” says Bendiksen.
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