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Table 5.7. Effects of otter
trawls on mixed substrate habitat: summary of published studies. (S = statistically
significant; citations in bold print are peer-reviewed publications.)
| No. |
Reference |
Location |
Depth |
Sediment |
Effects |
Recovery |
Approach |
| 1 |
DFO 1993 |
Bras d’Or Lakes, Nova Scotia, Canada |
10–500 m |
Mud, sand, gravel, and boulders |
Trawl
doors left parallel marks (furrows and berms), fainter marks from footgear,
primarily in mud. |
|
Sidescan
sonar survey after area was closed to mobile gear for 1 yr. |
| 2 |
Engel and
Kvitek 1998 |
California, USA |
180 m |
Gravel, sand, silt, and clay |
S
fewer rocks and biogenic mounds, S less flocculent material, and S more
exposed sediment and shell fragments in HF area; lower densities of large
epibenthic taxa in HF area (S for sea pens, starfish, anemones, and sea
slugs); higher densities of nematodes, oligochaetes, brittle stars and one
species of polychaete in HF area; no differences between areas for
crustaceans, mollusks, or nemerteans. |
|
Used
a submersible and grab samples (3 yr) to compare lightly trawled and heavily trawled commercial fishing sites with same
sediments and depth. |
| 3 |
Smith et al. 1985 |
Long Island Sound, New York, USA |
Not given |
Sand and mud |
Tracks
in sediment (<5 cm in sand, 5-15 cm in mud); attraction of predators;
suspension of epibenthic organisms. |
Tracks
"naturalized" by tidal currents. |
Video
and diver observations. |
|