Testing of Low-Profile Low Cod Bycatch Gillnets

Project Leader: Mike Pol, Massachusetts Division of Marine Fisheries

The first phase of this project was funded by the Northeast Consortium in 2000. This proposal seeks to continue field testing of two experimental gillnets designed by Robert MacKinnon. One experimental design adds lead weight to an otherwise ordinary floatline; the second experimental design replaces the floatline of the gillnet with another leadline. Both designs strive to reduce the vertical profile of the nets and exploit a behavioral difference between cod and flatfish. Fishing experience and video observation suggest that cod do not often venture to the very bottom of the ocean, and flatfish do not often rise more than one foot above the bottom. The ultimate use of the experimental nets, if proven, is to either allow fishing for flatfish in areas closed for cod, or to reduce the bycatch of cod in open areas.

Fifteen overnight sets of all four nets have been completed; data are currently being analyzed. Field testing was designed to allow comparisons of catch rates of cod and commercially valuable flatfish between experimental nets and standard nets. Results so far indicate that the design with added lead catches less cod than the standard cod and flatfish nets; the mean catch rate of the dual leadline net is lower than the standard nets, but not significantly so. Insufficient quantities of flatfish were captured in the nets to allow comparisons of flatfish catch rates.

The lack of flatfish is probably a result of testing in suboptimal places and times. The time and place of these fifteen sets was constrained by area closures and severe weather. This proposal seeks additional funding to allow further testing in February and March 2002 in Area 125. Area 125 is closed to commercial fishing during this time period because of high concentrations of cod. This time and place are our best chance to test these nets where sufficient densities of cod and flatfish are present to allow valid comparisons. Entering the closed area to perform this experiment will require an Experimental Fishing Permit (EFP) from the National Marine Fisheries Service (NMFS).

The experimental design and protocol proposed do not substantially differ from the testing funded in 2000 by the Consortium. The development of this proposal was encouraged following the submission of a Planning Letter. (abstract)

Related data objects:

Testing of Low-Profile, Low-Bycatch Gillnets
Temperature recorded from data loggers on "lo-lo" gillnets

gillnets_summary.csv