Georges Bank's Habitat
Georges Bank is an entirely offshore ecosystem, separated from the eastern coast of Cape Cod by the Great South Channel. This eco-region is bounded by the Northeast Channel to the north and by the continental shelf break to the south (1). It is also defined by unique water circulation patterns such as a large clock-wise gyre that develops in springtime (5). Georges Bank is a shallow plateau with an average depth of 90 feet. A high degree of light penetration and upwelling make it a very productive area, particularly in spring. In addition, the top of the Bank is tidally mixed, accounting for high nutrient levels that explain the high productivity of plankton, shellfish, and finfish in this area.
Georges Bank stretches 150 miles in an east-west direction, effectively blocking the southerly Gulf Stream from entering the Gulf of Maine, and sustaining the Gulf of Maine’s internal gyre by blocking the northerly Labrador Current from flowing southward. Ninety-eight miles at its widest point, Georges Bank acts as an offshore buffer between Southern New England and the Gulf of Maine, just as Cape Cod divides the inshore portions of these two ecosystems.
The Bank’s topography is relatively even, but some areas are shallower than others. The Cultivator Shoals, North Shoal, and Southwest Shoal, and East Shoal, can be as shallow as 12 ft., and breaking waves are not uncommon here. To the South and East, eleven canyons cut into the Bank. Most of the Bank’s bottom is sandy, but there are patches of gravel, rocks, pebbles, and sand waves (which can be up to 65 ft. high). A 1,150 square-mile gravel ‘pavement’ covers the northeast part of the Bank; this area is preferred by juvenile cod and haddock, because they can blend into the sediment.
Georges Bank shares many species with Southern New England, and some scientists have classified it as an extension of this neighboring eco-region. Others have grouped it with the Gulf of Maine, with which it shares oceanographic features. However, many fish species, such as yellowtail and winter flounder, have distinct Georges Bank subpopulations, suggesting that it behaves ecologically as an independent ecosystem (1).