Table
5.9. Effects of New Bedford-style scallop dredges 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 |
Caddy 1968 |
Northumberland Strait, Gulf of St. Lawrence, Canada |
20 m |
Mud and sand |
Drag
tracks (3 cm deep) produced by skids; smooth ridges between them produced by
rings in drag belly; dislodged shells in dredge tracks. |
|
Diver
observations of physical effects of two tows. |
| 2 |
Caddy 1973 |
Chaleur Bay, Gulf
of St. Lawrence, Canada |
40-50 m |
Gravel over sand, with occasional boulders |
Suspended
sediment; flat track, marks left by skids, rings, and tow bar; gravel
fragments less frequent (many overturned); rocks dislodged or plowed along bottom. |
|
Submersible
observations of tow tracks made <1 hr after single dredge tows. |
| 3 |
Mayer et al. 1991 |
Coastal Gulf
of Maine, USA |
8 m |
Mud, sand, and shell hash |
Lowered
sediment surface by 2 cm, injected organic matter and finer sediment into
lower 5-9 cm; increased mean grain size in upper 5 cm; disruption of surface
diatom mat; increased microbial biomass at sediment surface. |
|
Experimental
study, compared dredged and undredged sites before and 1day after a single
dredge tow. |