Stellwagen Bank Marine Sanctuary

Last weekend I spent 4 days in the Boston area whale watching with the grandkids. Marilyn and I had been to the area a few years ago to hear Neil Young at the famous Wang Performance Theater and while in the area spent a week on Cape Cod whale watching in the southern edge of the Stellwagen Bank Marine Sanctuary leaving from Provincetown on Cape Cod.

This time we left from Gloucester on Cape Ann in the north area of the Stellwagen Bank, namely Jeffrey’s Ledge. We had a couple of great trips and got to watch Humpback whales up close feeding, flopping their tales and waving pectoral fins, as well as doing complete rollovers just meters from our boat. Needless to say, the grandkids had an amazing time.

The Stellwagen Bank National Marine Sanctuary is an 842-square-mile federally protected Marine sanctuary at the mouth of Massachusetts Bay between Cape Cod and Cape Ann. It is known as an excellent whale watching site, and is home to many other species of marine life.

The heart of the sanctuary is Stellwagen Bank, an underwater plateau stretching 19 miles north to south, and six miles across at its widest, near the southern end. The bank is, on average, 100 to 120 feet below the surface, while surrounding waters to the west are over 300 feet deep and to the northeast as deep as 600 feet.

Upwelling at the shelf break occurs because there are currents flowing along the coast, slower moving water at the bottom of the ocean due to friction, stratified water separated by density, salinity, and temperature, and a dramatic change in seafloor slope. The underwater cliff-edge of Stellwagen Bank runs parallel to the coastline and is referred to as the shelf break. The shelf break is a steep slope which descends thousands of feet to the ocean floor. Deep nutrient rich currents are forced upwards toward the surface when they come into contact with the steep slopes of the bank’s plateau. This upwelling brings nutrients to the surface for phytoplankton, which brings larger organisms to feed.

Over 130 species from numerous classes of the animal kingdom call the bank home at least temporarily. Some such fish are the Atlantic cod, silver hake, yellow-tail flounder, blue-fin and yellow-fin tuna, striped bass, blue fish and numerous species of shark including the great white shark. Shellfish such as the American lobster, sea scallops, squid and ocean quahogs are also prevalent.

Many marine birds call the bank home including gannets, shearwaters, storm petrels, fulmars, puffins and razorbills. Reptiles are even present, primarily being represented by the leatherback sea turtle.

The most famous animals on Stellwagen Bank are the mammals. Five species of seals (harp seal, gray seal, harbour seal, hooded seal, and ringed seal) and numerous whale species swim in the waters of Stellwagen.

Whale watchers can frequently see humpback whales, minke whales, and fin whales. There are occasional sightings of one of the most critically endangered whale species, North Atlantic Right Whales.

The Stellwagen Bank owes much of its existence to the last major ice age. 25,000 years ago, the Laurentide Ice Sheet advanced over the eastern United States, pushing in front of it large amounts of earth and rocks. The southern margin of the glaciers formed local geographical features including Cape Cod and Stellwagen Bank.

A video my daughter-in-law Theresa shot on our trip with her phone of a humpback flopping around waving it's pectoral fin then rolling over.

In the 17th century it was observed that the area made for excellent fishing. Large cod and tuna were frequently caught in the area, and whaling ships caught many whales in the area.
In 1854, the US Navy sent Lieutenant Commander Henry Stellwagen to survey and map the area. It was known that there was a bank in the area, but its extent and shape were not known.

Humpback pectoral fin from a previous whale watching excursion.

Prior to Stellwagen's survey, it was believed there were two small banks in the area: one just to the north of Cape Cod, and one in the middle of the entrance to Massachusetts Bay. Stellwagen showed that they were part of one large bank. As a result, the Navy named the bank after him in 1855.

On October 7, 1992, Congress designated the area a National Marine Sanctuary.

For more information on Humpback Whales check out the Humpback Whale blog from Alaska