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Commercial Fisheries News
Volume 34 Number 5
January 2007
‘Five-Point Haddock Trawl’ slashes cod catch
This is the third installment in our ongoing series examining the performance of various haddock net designs that fishermen and scientists around the region have been testing in cooperative research projects. The goal is to find a net that New England fishermen can use to target abundant haddock stocks while avoiding other low-quota species such as cod and yellowtail.
Here, Massachusetts Division of Marine Fisheries gear engineers David Chosid and Mike Pol describe the field test results of the “Five-Point Haddock Trawl” designed by Tor Bendiksen of Reidar’s Manufacturing Inc. in Fairhaven.
—Editor
NEW BEDFORD, MA – “How can we catch haddock and not cod?” That is the question on the minds of many managers and fishermen in the Northeast. The Georges Bank Atlantic cod stock is overfished while haddock stocks seem to have rebounded in some areas. However, groundfishing is generally not selective for single species.
There are basically two ways to effectively manage individual fish stocks – consider them as part of a multispecies fishery or develop gear that selects primarily for the targeted species. The latter method has sparked an interest in testing a number of variations of the haddock separator trawl. The Massachusetts Division of Marine Fisheries (DMF) has designed its own version, which is known as the “Five-Point Haddock Trawl.”
The National Marine Fisheries Service (NMFS) allows the limited use of trawl net horizontal separator panels within the Eastern US/Canada area of Georges Bank. This panel tries to take advantage of differences in the behaviors of Atlantic cod and haddock. As a trawl net approaches the fish, haddock generally swim upward into the top section above the panel while cod stay low and swim out through an open-bottom codend.
However, the effectiveness of the separator panel is unknown, it adds additional complexity to the fishing operation, causes drag that burns fuel for a nonfunctioning codend, and is associated with an “escape mortality” for those cod that were chased but not retained.
For these reasons, the Marine Fisheries Institute funded the Five-Point Haddock Trawl project. Michael Pol and David Chosid of DMF conducted research and field operations.
The Five-Point Haddock Trawl was designed by Fairhaven net maker Tor Bendiksen and constructed by Reidar’s Manufacturing, and the initial model was tested at the Memorial University’s Fisheries and Marine Institute’s flume tank in St. John’s, Newfoundland.
The net is a three-bridle, four-panel box trawl modeled after a sweepless raised footrope trawl. This semipelagic net rides about 1-2 meters off-bottom and only contacts the ground with the ends of five “drop chains” hanging from the fishing line.
These chains maintain net shape. The height of the fishing line off the bottom can be adjusted using the bottom leg or bridle. Furthermore, the drop-chains maintain a stable height off-bottom over varying speeds.
Catch results
Field testing comparing the Five-Point Haddock Trawl and a standard trawl net was conducted in June and July of 2006 and consisted of 91 combined twin trawl and alternate trawl tows on the fishing vessel Mary Elena of Point Judith, RI in the Eastern and Western US/Canada areas of Georges Bank and in the haddock special access program (SAP).
Catch data, sensors, and video cameras were used to demonstrate that the five-point trawl was operating as expected and could be used to target haddock effectively with low bycatch of cod.
The results of these trials show that cod catches are reduced to very low levels compared to the standard net – a 98% reduction.
Furthermore, haddock, although patchily distributed, are effectively caught using the experimental net without significant differences from the control net.
On smoother bottom habitats, higher haddock catches were generally observed with the control net. However, the Five-Point Haddock Trawl net obtained higher haddock catches in rocky fishing areas. Additionally, this net has the added benefits of almost no ground contact, minimal bycatch, and reduced drag as compared with a standard bottom trawl.
Cod that would otherwise have to pass through a separator trawl are instead just passed over by the five-point trawl, reducing a source of stress on the fish. Length frequencies were alike for both the experimental and control nets.
The table that follows shows the percentage reduction in total catch by the experimental Five-Point Haddock Trawl net compared to a standard haddock trawl net for 10 commercially important species.
What’s next
Our goal was to improve upon the separator trawls currently used by fishermen. These initial results are very encouraging, but more data are needed to make a solid argument that the Five-Point Haddock Trawl should be allowed for use in the haddock SAP.
Future research will concentrate on further refinement and adjustments to the experimental net with specific attention towards fishing on rocky areas January to March.
The goal of continuing this work is to maintain higher catches of haddock and low catches of cod. Plans are underway for DMF to partner with the University of Massachusetts’ School of Marine Science and Technology and three New Bedford fishing vessels to continue this work on Georges Bank.
David M. Chosid
Michael V. Pol
David Chosid and Mike Pol work in the Massachusetts Division of Marine Fisheries (DMF) Conservation Engineering Program, which is now based at DMF’s South Shore Field Office in New Bedford.
Chosid, who is a recent addition to the group, specializes in experimental design and the analysis of fish stocks and gear efficiency. Pol, a senior marine biologist who leads DMF’s Conservation Engineering Program, has extensive experience with gear research and data analysis.
For more information on the Five-Point Haddock Trawl contact them as follows: David Chosid, phone (508) 990-2860 ext. 140 or e-mai• <david.chosid@state.ma.us>; or Mike Pol, phone (508) 990-2860 ext. 116 or e-mail <mike.pol@state.ma.us>.
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