Great South Channel
Overview
The Great South Channel is a prominent feature in the bathymetry of the Gulf of Maine; along with the Northeast Channel, it provides an oceanographic connection between the Gulf of Maine and the Northwest Atlantic Ocean. The channel is a transit route for the endangered Northern Right Whale as it migrates between summer and winter habitats.
Surface area (percentage of total)
2,007 mi2 2%
Depth
50 m – 100 m
Bathymetry including key features
The funnel-shaped Channel is wider and deeper at its northern end.1
Substrate
Sediments include gravel pavement and mounds, occasional boulders, sand with ripples generated by storms, and scattered mussel beds.
Relationship to large-scale circulatory patterns of the Gulf of Maine
In general, water flows into the Gulf from the Scotian Shelf and through the Northeast Channel at depth (river discharge during the spring freshet makes up a third source). Outflow occurs through the Great South Channel and mid and surface layers of the Northeast Channel.2,3,4
Information on average (seasonal/annual) oceanographic conditions
The Great South Channel is well mixed due to tidal currents and the existence of a frontal system between Gulf of Maine waters and those of the Continental Slope.5 The front separates the warmer, surface, stratified waters of the Gulf to the north from the cooler, tidally mixed waters south of the front.6
Trawl survey stations
NEFSC Bottom Trawl Survey – Spring
Average number of tows per year: 6
Number of years for which data is available: 36
Range of years for which data is available: 1968-2003
NEFSC Bottom Trawl Survey – Fall
Average number of tows per year: 7
Number of years for which data is available: 41
Range of years for which data is available: 1963-2003
DFO Bottom Trawl Survey
Average number of stations sampled: 5
Number of years for which data is available: 14
Range of years for which data is available: 1986-2001
NEFSC Shrimp Survey
One tow each in 1985 and 1987
NEFSC Scallop Survey
Average number of tows per year: 23
Number of years for which data is available: 26
Range of years for which data is available: 1975-2003
NEFSC Clam and Quahog Survey
Average number of tows per year: 1
Number of years for which data is available: 8
Range of years for which data is available: 1982-1999
ECNASAP standardized trawl records
Average number of tows per year: 16
Number of years for which data is available: 25
Range of years for which data is available: 1970-1994
Whale abundance, distribution and migratory patterns
A portion of the Great South Channel is designated as a "critical habitat area" for the Northern Right Whale, designated as an endangered species by the National Oceanic and Atmospheric Administration. Right whales feed on plankton in the Great South Channel in mid to late spring.
1 NOAA, Undated
2 Xue, et al., 2000
3 Pettigrew, et al., 2005
4 Maine Ecosystem Dynamics Modeling Laboratory, Undated
5 Velntine, 1999
6 NOAA, Undated