Smooth Bottom Net Trawl Fishing Gear Effect on - New England ...

NOAA/NMFS Unallied Science Project, Cooperative Agreement NA16FL2264 May 2005
<strong>Smooth</strong> <strong>Bottom</strong> <strong>Net</strong> <strong>Trawl</strong> <strong>Fishing</strong> <strong>Gear</strong> <strong>Effect</strong> on the Seabed:
Investigation of Temporal and Cumulative <strong>Effect</strong>s BKAM/CR
Figure 3.2.2.4 –1b November 2002 grab sample locations along Mud Hole Lane 1 at station B.
Mud Hole Control Lane 2 in the Vicinity of Station B
Bathymetric data shows that station MH-2B is located at the toe of a slope that rises to the
northwest (Figure 3.2.1-1) in an area that appears to be characterized by flat sandy mud (see
Appendix 3.2A Figure TS-6). Pre-trawl sonar data for station MH-2B shows faint background
trawl gear impacts.
Lane 2 in Mud Hole was designated a control lane, however, some project-related gear impacts
were observed in the western portions of the September 30 th and November 20 th sonar imagery in
the vicinity of MH-2B. These gear impacts appear to have come within approximately 25meters
of the centerline of lane 2, i.e. just within the western edge of this control lane. As shown
on Figure 3.2.2.4-2a (below) two of the grab samples collected in October may have been
compromised by these trawl impacts (i.e. the MH2B grain size sample and the MH-2B benthic
grab replicate 1). All November grab samples were collected from non-impacted areas closer to
the center of this control lane (Figure 3.2.2.4-2b). Background door marks were still visible on
the September and November side-scan imagery. Again trawl scours in November appeared
broader and less distinct than in previous records and likely due to sediment transport from
bottom currents associated with the November storm.
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