Last month, an acoustic monitoring buoy was put in place in the New York Bight, listening out for sounds from some of the world's largest mammals. A joint project between the Woods Hole Oceanographic Institution (WHOI) and the Wildlife Conservation Society's (WCS) New York Aquarium, the buoy has already picked up sounds from a herd of fin whales – the second largest whale species on the planet.

The buoy itself extends 6 ft (1.8 m) above the waves, and is tethered to the sea floor some 125 ft (38 m) below. The device is positioned between two shipping lanes, some 22 miles (35 km) south of Fire Island, close to the busiest port on the east coast, the Port of New York and New Jersey.

It has an underwater microphone, or hydrophone, on board, recording and processing sounds from the deep, with specially developed software picking out whale sounds and broadcasting the data back to shore via satellite. That info is designed to help scientists better understand how whales are being affecting by high noise levels and the general disruption caused by intense shipping.

The buoy was successfully deployed on June 23, and it's monitoring equipment almost immediately started detecting the vocalizations of fin whales. The first detection of the giant marine mammals was made on July 4, just 12 days after the buoy was deployed. Since then, it's picked up the fin whales several times, most recently on July 27. The sounds made by the whales are of such a low audio frequency that they can only be heard by humans after being sped up several times.

"After years of planning, it's great that we're now in the water and receiving our first data – detections of fin whale vocalizations from the buoy over many days in the last few weeks," said project co-lead Dr Howard Rosenbaum. "By detecting whales in this area, we will get a much better understanding of how they are using the waters off New York and how to better protect them."

As much as 20 ft (6 m) in length at birth, they can grow up to 70 ft (21 m), and can weigh in at several tonnes. The species is characterized by a prominent dorsal fin that sits two-thirds of the way down its back.

After being hunted for a large part of the 20th century, fin whales are an endangered species. With only an estimated 1,500 of the animals remaining off the east of coast of the United States, it's an appropriate species for study, with the mammals suffering from high mortality rates at the hands of ship strikes and entanglement with fishing equipment.

As the buoy continues to listen out for the marine mammals, the researchers expect to pick up sounds from other species, including one of today's the most endangered animals – the North Atlantic right whale. Improving our understanding of the species is of paramount importance, with just 500 or so thought to be left in world's oceans.

"We're excited to share this discovery with the residents of New York City and to help promote a better awareness of these marine mammals in the region," said Jon Forrest Dohlin, Vice President and Director of the New York Aquarium. "The acoustic buoy will help us monitor the whales and learn more about their needs. New Yorkers can now share in that process of discovery and conservation."

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