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

NOAA/NMFS Unallied Science Project, Cooperative Agreement NA16FL2264 December 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
3.6 Fisheries Survey Results
3.6.1 <strong>Trawl</strong> Catch Results
A total of fifteen fish species and six invertebrate species were identified from the trawl
catches during the three experimental trawl surveys in early August (pre-chronic
trawling), and October and November (post-chronic trawling) at the Mud Hole and Little
Tow sites. Refer to Table 3.6-1 for a list of the fish and invertebrate species caught during
the 2002 trawl study.
To help interpret the catch results from the experimental trawling surveys at Mud Hole
and Little Tow, the data were viewed in several different formats:
• Tables of Catch by Species in kg per Tow (Table 3.6-2);
• Graphs of Overall Catch (Figure 3.6-1), and Average Catch per Tow (Figure 3.6-
2), and Catch Composition for Mud Hole and Little Tow trawled lanes (Figure
3.6-3);
• Graphs of Densities (weight in kilograms per 1000 square meters) based on
weight of major demersal species caught and the area swept during each tow
(Figures 3.6-4, 3.6-5, 3.6-6);
• Graphs of Species Density (numbers per 1000 square meters) based on numbers
of major species of commercially targeted flounder caught, and the area swept
during each tow (Figure 3.6-7);
• Length frequency distributions of target species, winter flounder and yellowtail
flounder, at Mud Hole (Figures 3.6-8 and 3.6-9) and Little Tow (Figures 3.6-10
and 3.6-11);
Seasonal trends over the study period are clearly seen in the catches sampled during each
of the experimental trawl surveys (Figures 3.6-1 and 3.6-2). In general, flounder and
skate abundance increases in the fall, as the rock crab abundance declines. Spiny dogfish
are found sporadically throughout the study period. Many species are present, such as
Atlantic cod, windowpane flounder, American lobster, and squid, but due to their low
densities, little can be said about their abundance or movements. Focus was placed on
bottom feeding commercially important demersal finfish, targeted by otter trawling.
Yellowtail flounder and winter flounder were the most closely studied, being predators
on benthic infauna and having sufficient numbers to provide an adequate data set.
The entire catch of these flatfish were sorted, weighed and measured. A subset thereof
had their stomachs removed and preserved individually for identification of their contents
(see Section 3.6-2 below).
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