The Gulf of Maine

A bathymetric map of the gulf of Maine.

The Gulf of Maine is a unique marine environment located off the shores of southeastern Canada and coastal New England. Many people have visited beaches and harbors that border the Gulf of Maine or have traveled through its waters aboard vessels heading offshore. Yet we are more familiar with the features and basins that make up this immense gulf than we are with the Gulf of Maine itself.

For a larger version of the map on your right click here

Underwater features such as Jeffrey’s Ledge, Stellwagen Bank and George’s Bank are common names to many people living in this area. Also most are familiar with its deepwater basins, such as the Bay of Fundy, Cape Cod Bay and Massachusetts Bay, including the waters of the Stellwagen Bank National Marine Sanctuary. These areas comprise one of the most biologically productive marine ecosystems in the world, one that supports a diverse array of organisms that includes over 2,000 species of plants and animals.

To learn more about what you can find underneath the Gulf's surface, take a Underwater tour of the Seafloor Landscapes in the Gulf of Maine Region.

The Gulf of Maine is often referred to as the “sea within a sea” as it is a semi-enclosed area bounded to the south and east by large underwater banks. This gulf encompasses over 93,000 square kilometers (36,000 square miles) of ocean and has an average depth of only 150 meters (492 feet). The shores of the Gulf of Maine are bounded to the west by New Brunswick, Nova Scotia, Maine, New Hampshire and Massachusetts, creating over 12,000 kilometers (7,500 miles) of rocky coastline. Cape Cod and Cape Cod Bay define the southern boundaries of the Gulf of Maine while Georges Bank defines its most southwestern boundary.Bathymetric view of Georges Bank.

To the right we have a bathymetric view of Georges Bank, an important feature in the Gulf of Maine. This map comes from Penobscot Bay Watch site that also posts parts of a 2005 report titled "Fishing Grounds in the Gulf of Maine" by Walter H. Rich of the U. S. Bureau of Fisheries. If interested, click here to read the Project Gutenberg eBook version of this report.

The presence and features of Georges Bank greatly impacts the characteristics and productivity of the Gulf of Maine. This feature is part of the continental shelf and is located 100 kilometers (63 miles) offshore. Georges Bank is approximately 240 kilometers (149 miles) in length and 120 kilometers (75 miles) in width. This immense underwater bank creates a situation where the Gulf of Maine is more greatly influenced by the colder waters of the Labrador Current from the north than the Gulf Stream waters to the south. Therefore, the waters of the Gulf of Maine are more nutrient-rich than more southern waters, an important factor that helped sustain this area as a historical fishing grounds over the centuries

The geology of the Gulf of Maine is based upon the movements of large ice sheets that originated in the Hudson Bay area of Canada approximately 25,000 years ago. The movement of glaciers scoured the bedrock through a series of advances and retreats. During periods of glacial melting, elevated areas were created as glacial runoff deposited massive amounts of rock and rubble at the base of the glaciers. These elevated areas would later become underwater banks or ledges as the ice sheets continued their retreat causing a rise in sea level. Examples of inshore ledges and banks include Jeffrey’s Ledge and Stellwagen Bank while more offshore features include Browns Bank and Georges Bank.

The Gulf of Maine is one of the most biologically productive ecosystems in the world that is home to a diverse array of marine microorganisms, plants and animals. Some organisms, like phytoplankton, are microscopic in size, yet play a vital role as producers that can make their own food through the process of photosynthesis. Other organisms are not capable of making their own food, so these consumers must eat phytoplankton or other marine organisms to survive. Large or small, abundant or rare, all living organisms interact to maintain this intricate dance called the web of life. The loss or overabundance of a species or group can greatly impact the lives of the other organisms that are intertwined in this delicate fabric of life.

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