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Geography: Where is Casco Bay in the world’s oceans?

Geography Lesson: Where is Casco Bay in the World’s Oceans?

Casco Bay is part of a larger ocean system called the Gulf of Maine, a semi-enclosed body of water within the Northwest Atlantic Ocean. Bounded by Nova Scotia, New Brunswick, Maine, New Hampshire, and Massachusetts, it forms what people call “New England’s Own Ocean.” Georges Bank and Browns Bank form its eastern rim, setting the Gulf of Maine apart from the rest of the Atlantic Ocean.  These relatively shallow waters have been rich fishing grounds for cod and other fish for over 400 years. The Gulf of Maine is slightly larger than the state of Maine.

Why the Gulf of Maine is good for fishing

If you have ever jumped into the ocean in Maine, you know it is COLD! Cold water holds more oxygen than warmer waters. Both animals and plants need oxygen to live.

Nutrients from land are carried by rivers into the Gulf of Maine, where they fertilize the cold waters and promote the growth of tiny plants, phytoplankton, the base of the ocean food chain.

Cod and their relatives, pollock, hake, and haddock, have firm, tasty flesh. This white fish is sought after by diners, and so the fish are sought after by fishermen. Many cold-water fish travel in giant schools, which makes it possible—and profitable—for fishermen to capture thousands of fish at a time. They drag huge nets along the ocean floor. When the fleeing fish become tired, they are swept into a smaller net at the back, appropriately called the “cod end.” They are described in Fishes of the Gulf of Maine at http://gma.org/fogm.

Where is the best fishing?

On a map of the world, locate these prime fishing grounds. What bioregions are they in? [cold water]

  • Georges Bank, off Massachusetts
  • Grand Banks, off Newfoundland
  • Southern Africa
  • North Sea
  • Iceland
  • Norway
  • Barents Sea
  • Bering Sea in the North Pacific
  • Gulf of Alaska
  • Coastal areas around Japan
  • Northeast Pacific


Many of the most popular food fish have declined by 80% or more from overfishing and habitat destruction. Find out more about the Sustainable Seafood movement at Seafood Watch, Sustainable Seafood:  www.seafoodwatch.org


Find the Gulf of Maine on a globe

The ocean has different climate regions, just like there are on land.

Look at a globe of the world. The bioregions of the world are defined by their distance from the imaginary line around the center of the earth, the Equator.


Latitude and longitude are the two grid coordinates by which one can locate any point on Earth. Lines of longitude run north and south. Greenwich, England, has been designated to be 0 o longitude. Locations are calculated E or W of this imaginary line. Portland is about 70oW longitude.

Latitude is measured in degrees North and South of the Equator. The Equator is at 0 o latitude. Our latitude in Maine is around 45oN.

Find these latitudes on the globe:

  • 5oS to 23.5oN: Tropical region
  • 5o to 66.5oN and S: Temperate regions
  • 5oN to 90oN and S (Arctic and Antarctic): Polar regions


Find Maine on a globe and follow the latitude line around the globe to see what other countries are on the same parallel of latitude. Do you think these countries have the same climate as we do? Do the same with the line of longitude. Do these have different climates? The distance from the Equator affects how warm and cool a region is, and ocean currents also warm and cool a region.

If you were a fish, where would you rather live?

If you were to ask people to picture where in the world oceans they would find the largest number of fishes, most would say the tropical seas, conjuring up images of a vivid, bustling coral reef. But consider the locations of the major fisheries of the world, which depend on netting huge quantities of fish in each tow; they are in cold waters. Temperate and cold seas are home to relatively few species of fishes, but many individuals, and while tropical waters offer a staggering variety of life, there are far fewer individuals of each species.

 “Country Fish”: The fishes of cold and temperate waters

The cold waters of temperate and frigid seas may look murky, but they aren’t polluted. It’s the rich sea soup of plankton that reduces visibility to a few feet under the water and makes it appear green above. Advantage: Abundant food


“City Fish”: Coral reef residents

Tropical seas are hugely popular with divers and underwater photographers because the water is so clear. That is because there is relatively little plankton floating in the water to obscure your view.

In comparison to colder waters, tropical seas are relatively empty, except for coral reefs. A coral reef is like a city in the desert—an oasis—which may provide the only food and shelter for many miles around. The animals there have evolved complex strategies to compete for the limited food and hiding places within the shelter of the coral reef.  Advantage: Many hiding places