GRANT
NUMBER:
NA46FD0325
NMFS NUMBER: 93-NER-015
REPORT
TITLE:
Reduction
of Flatfish Bycatch in the Small-Mesh Bottom Trawls Used
in the New England Whiting Fishery: An Investigation of
Fish Behavior and an Evaluation of Separator Trawl Technologies
AUTHOR:
Joseph
DeAlteris
PUBLISH
DATE:
July 10, 2001
AVAILABLE
FROM:
National Marine Fisheries Service, Northeast Region, One
Blackburn Drive, Gloucester, MA 01930-2298. PHONE:
(978) 281-9267
ABSTRACT

Experiments
were conducted to evaluate two different strategies for
the reduction of flatfish bycatch in the small-mesh groundfish
bottom trawl. The first set of experiments was devoted
to modifications of the fishing line and sweep. Vertical
openings of varying height separating the fishing line
from the sweep were evaluated, as were discontinuities
in the bosum of the sweep. Of the four modifications tested,
only one experimental trawl with a 2.1-m long by 0.3-m
high discontinuity in the sweep resulted in significant
reductions in flatfish bycatch (96% on average) while
not affecting catch of target fish. The second set of
experiments was directed at modifications that included
an escape panel in the lower belly. The escape panels
were designed with openings of different sizes and twines
(color and diameter). Of the four modifications tested,
again only one experimental trawl with 40.6-cm diamond-shaped
meshes constructed with 1.6-mm diameter orange-colored
twine proved effective in significantly reducing the flatfish
bycatch (73%) while not affecting the catch of the target
species. Both strategies are simple and could be easily
incorporated into similar small mesh bottom trawl fisheries
in New England.