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Commercial Fisheries News
Volume 34 Number 3
November 2006
Coffin haddock net yields mixed results
Conservation gear engineers and fishermen across New England have been working hard to come up with practical net designs that can catch haddock, which is a healthy fish stock, while avoiding low-quota species such as cod and yellowtail.
Successful trials and subsequent approval by the National Marine Fisheries Service of one or more of these net designs could be a real boost to the New England groundfish industry.
The gear approval process is often a lengthy and frustrating one. However, the people involved with this work firmly believe they’re making headway. In the coming months, CFN will feature progress reports on several of these “haddock nets.”
Dana Morse of Maine Sea Grant and University of Maine Cooperative Extension kicks off this series with a description of the Coffin net. –Editor
BOOTHBAY HARBOR, ME – In 2003, the Northeast Consortium (NEC) funded a trawl research project entitled “Selective Gear Research and Development to Reduce Bycatch: Investigating the Use of Square Mesh Side Panels and Increased Taper in a Groundfish Trawl.”
The project was a collaboration primarily between the late Capt. Stanley Coffin of Edgecomb, ME, who had the original idea, fisherman Kelo Pinkham of Boothbay, and Dana Morse of Maine Sea Grant/Cooperative Extension, who was the scientist on the project.
Fishing trials were conducted aboard the 54' Bad Penny out of Boothbay Harbor, owned by Stanley and Claudia Coffin.
As a research project, the results were mixed. What follows are some details from that original effort and information on a follow-up project, also funded by the NEC. This latest project aims to continue refining the design with the goal of maximizing escapement of small cod and haddock while maintaining the catch of marketable fish.
Given the concern over the growth in population size and the possible concurrently high discard rate of Georges Bank haddock, we hope that the trawl modifications being tested will eventually provide fishermen with a relatively straightforward, regulation-compliant means to reduce the capture of small haddock and cod.
Net modifications
In the first set of trials, we tried two modifications to a typical groundfish trawl to improve escapement of small cod and haddock. We converted a typical two-seam design – 100' headrope, 120' sweep – to a four-seam net, with the side panels being made of 6" twine in the diamond configuration. This net served as our control.
It was fished against an identical experimental net in which the side panel had 6" mesh but turned in the square position. The side panel was 15 bars deep – with one bar equal to one mesh opening since the meshes were turned square – with two bars sewn into each gore, leaving 11 open meshes in the panel and extended from the front of the mouth back to the beginning of the cod end.
In an effort to provide some vertical spread in the side panel, the top gores on both sides of the experimental net had 8" trawl floats spaced periodically along them and the bottom gores had 3/8" lead line attached.
Both nets used a 2:1 taper in the belly sections. We performed field trials in an alternate-tow approach and completed 21 pairs of tows with these nets.
In the second set of field trials, the control net stayed the same, but was fished against an experimental net in which the taper had been cut down to a 5:1 in an attempt to stimulate escape behavior by cod and haddock. The square mesh panel was the same, as was the flotation and the weight on the gores. These two nets were fished for 19 pairs of tows.
Results
Of the two sets of experiments, the 2:1 trials were modestly more promising. The 2:1 experimental net reduced the catch of undersized cod by 95% (control = 521 lbs, experimental = 25 lbs), small haddock by 96% (control = 107 lbs, experimental 4 lbs), and did not significantly change the catches of dabs, grey sole, monkfish, hake, skate, and several other species.
In addition, the experimental net retained more market size cod than did the control trawl (3,225 pounds for the control vs. 3,657 pounds for the experimental) over the 21 tow pairs.
However, there was a reduction in the catch of market size haddock observed with the experimental, which caught 667 pounds compared to the 3,015 pounds that the control caught.
So, in general, while the escapement appeared to be a positive sign for the sublegal fish, the loss of marketable haddock would likely be a problem for fishermen.
Next step
In an attempt to find a trawl design that allows optimal escapement of undersized fish but retains market size fish, the NEC has funded a follow-on study that will examine the use of 6" hexagonal mesh in the side panel of a trawl.
This study, entitled “Building on Promise: Continued Investigation in using a 4-seam Bottom Trawl to Improve Escapement of Small Haddock and Cod,” is in the early stages and fieldwork will begin later in 2006.
For more information on these projects, call Dana Morse at Maine Sea Grant, (207) 563-3146, ext. 205, or e-mail him at <dana.morse@maine.edu>.
Dana Morse
Dana Morse is a member of the University of Maine Marine Extension Team (MET), a collaboration of Maine Sea Grant and the University of Maine Cooperative Extension. Its members live and work along the coast, providing educational and applied research programs to Maine’s citizens in the areas of coastal community development, ecosystem health, fisheries, and aquaculture.
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