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What's causing the unusual strandings and deaths among whales?

Scientists explain the causes behind unusual numbers of whale strandings and deaths on the U.S. Atlantic coast.
Posted at 10:53 PM, Jun 05, 2023

In the massive, perilous, and deep oceans are one of the most mysterious and intelligent creatures humankind has ever seen.

Whales are marine mammals: They breathe air like we do, reproduce through internal fertilization, and their expressive eyes have the same general anatomy as ours.

Despite our points of connection, humans have placed their existence in danger.

"You can't save the whale if it doesn't have a healthy environment for it to live in," said Alexander Costidis, senior scientist at the Virginia Aquarium & Marine Science Center.

Since 2016, the National Oceanic and Atmospheric Administration has recorded hundreds of whale strandings along the Atlantic coast of the United States, declaring it an unusual mortality event.

"There are currently three separate large whale unusual mortality events," said Costidis.

The concurrent and unusual whale mortality includes minke whales, with 142 strandings since the beginning of the mortality event; humpback whales, which have the highest number of mortalities amongst active cases with 194 documented strandings; and the North Atlantic right whale, with 98 strandings to date.

Costidis, who leads the Virginia Aquarium & Marine Science Center's Stranding Response Program, says data collected from examinations of dead whales have identified the leading causes of whale mortality.

"Most of the humpback whales we find are killed by either vessel strikes or entanglements, and that's similar for North Atlantic right whales as well, which are even more concerning given their population numbers," Costidis said. "There are peaks and troughs in terms of strandings, and a lot of that has to do with when the whales are in town. So, all of these species migrate north to south and so, when they're in our neck of the woods, we tend to see spikes or elevations in those mortalities."

According to Dave Wiley, a research ecologist at the Stellwagen Bank National Marine Sanctuary, a rising human population on the planet has fueled the supply chain; with most goods coming into the U.S. by ship.

"The more things that we need, the more materials that we want, then the more ships come through," said Wiley.

A whale

Why are more whales getting stranded on the East Coast?

A sudden rise of humpback whales and North Atlantic right whales stranded along the East Coast has stirred speculation on what's the real cause.


More ships are sailing to the East Coast while whales come close to shore searching for food.

"One of their favorite foods is a small fish called menhaden, and menhaden have a tendency to be very close to shore, which drives these humpback whales close to shore, where they're in contact with shipping more frequently than they were in the past," said Wiley.

Climate change is also impacting the world's oceans.

The Intergovernmental Panel on Climate Change, a body of the United Nations, explains that mobile species, such as fish, are moving to more favorable regions on a quest to find their preferred range of water temperatures or oxygen levels.

"They'll find areas where prey or food is concentrated and when the climate changes and the oceans warm and the prey moves, they'll follow the prey," said Dr. Andrew Read, professor of marine biology at Duke University.

According to NOAA, of the whales examined, approximately 40% had evidence of human interaction.

Costidis says when found, some whales are gravely decomposed, making it impossible for scientists to perform necropsies.

"They're partially buried, they're floating out in the open ocean," added Costidis.

But scientists say other efforts are necessary to protect these creatures.

Fish swim near bleached coral.

United Nations agrees on treaty to protect ocean life

After about 20 years of planning, U.N. members agreed to a treaty that will pave the way for protecting marine biodiversity in international waters.