New England Aquarium researchers recently documented what they say was a rare sighting of an endangered fin whale and its calf. 

Scientists on a July 24 aerial survey flew over the Northeast Canyons and Seamounts Marine National Monument, about 130 miles southeast of Cape Cod. They observed more than 1,000 marine animals, including seven fin whales, one endangered sperm whale, one humpback whale, two minke whales and more than 900 dolphins.

“Seeing an endangered fin whale and its calf is a rare occurrence,” assistant research scientist Kate Laemmle said in a statement Wednesday. 

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The fin whale and calf seen off Massachusetts.

New England Aquarium

The aquarium says the 5,000-square-mile monument has four underwater mountains and three deep-sea canyons. On past survey flights, enormous blue whales and other endangered whale species have been spotted in the monument waters.

“Each survey speaks to the remarkable array of biodiversity that we see in the Monument,” Laemmle said.  

According to the state’s endangered species program, fin whales are the second-largest whale species, growing up to 85 feet long and weighing up to 80 tons. They can venture within 10 miles of the Massachusetts coastline throughout the year.

Female whales typically give birth to a single calf off the mid-Atlantic states south between December and April. The fin whale population was once heavily hunted before federal protections, and now the biggest threats to the endangered population are ship strikes and entanglement in fishing gear.

The sperm whale is also endangered, with fewer than 6,000 believed to be in the North Atlantic. The species known for its big brain has been seen south of Martha’s Vineyard and Nantucket during summer aerial surveys.

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A sperm whale spotted by research scientists off Cape Cod.

New England Aquarium

Earlier this year, researchers installed high-tech buoys in Cape Cod Bay and off Cape Ann to listen for vocalizations from large whales, including the critically endangered North Atlantic right whale

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