Photograph by Paul Nicklen, Nat Geo Image Collection
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Since January 2016, scientists have counted 88 dead humpback whales along the East Coast—more than twice the number counted in the previous three-year period.

Photograph by Paul Nicklen, Nat Geo Image Collection

Whales are dying along East Coast—and scientists are racing to understand why

For more than two years, scientists have been working to figure out the underlying cause of this so-called “unusual mortality event.”

On a blustery winter afternoon off the coast of Virginia Beach, people are pressing forward on the bow of the Virginia Aquarium and Marine Science Center’s whale watching boat as a dorsal fin breaks the surface. Cameras click in staccato for a second or two before the humpback whale dives to feed again.

The relatively small dorsal fin belies the humpback’s size. Calves weigh about a ton. Adults can grow heavier than a yellow school bus loaded with kindergarten students. Few things that swim in the sea can break their bones.

A mile to the north, however, by the mouth of Chesapeake Bay, a massive cargo ship is pushing south toward the whales. On this Saturday in late January, these humpbacks are swimming in traffic in the shipping channel that leads vessels to and from some of America’s busiest ports. These shipping vessels are one of the few true physical threats to humpback whales.

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“Those big ships, they’re churning up the water and the fish are coming through and that’s what the whales are going for,” says Mark Sedaca, captain of the 65-foot Atlantic Explorer on this whale watching trip.

Whale researchers along the Atlantic coast say more stranded whales are showing signs of vessel strikes and fishing gear entanglement than ever before. From January 2016 to mid-February 2019, the National Oceanic and Atmospheric Administration (NOAA) recorded 88 humpback whale strandings with New York, Virginia, and Massachusetts at the top of the list.

Those numbers are more than double the number that of whales stranded between 2013 and 2016.

This increase prompted NOAA to declare an “unusual mortality event” in April 2017 for humpbacks from Maine to Florida. Nearly two years later, the declaration still stands.

The fourth unusual mortality event declared for humpback whales since 2003, this designation enables NOAA to redirect resources to investigate future strandings. But during a telephone conference shortly after the April 2017 announcement, questions outnumbered answers: Were there more whales traveling in shipping channels or more vessels? Was changing water temperature drawing prey closer to shore and drawing whales in too? Was ocean noise disorienting whales?

Not the first “unusual mortality event”

At the time, NOAA officials said those answers were “really hard to know” at such an early stage.The causes of the three previous unusual mortality events ultimately remained “undetermined.”

But three years after the first humpback showed up dead off the coast of Virginia Beach in January 2016, scientists at Virginia Beach aquarium think they’ve figured what might be killing the whales. “The conclusions are that the two overarching causes of it are vessel interactions and entanglements,” says Alexander Costidis, the aquarium’s stranding response coordinator.

But why it’s happening is “a little trickier,” one researcher said. Scientists still don’t understand why whales are swimming closer to ships or whether they detect and try to avoid them in any way.

Costidis’s team investigates every dead whale in the state, and when feasible, performs necropsies, or animal autopsies on them. The team also responds to strandings in North Carolina if needed. The crew, which receives NOAA funding, operates out of a nondescript building alongside a rail line about two miles from the coast. One might assume the building holds highway equipment, not tanks full of loggerhead and Kemp’s ridley sea turtles recovering from a recent cold snap.

When asked what a typical stranding response is like, Susan Barco, the aquarium’s research coordinator, burst into laughter. “Well, first you freak out,” she says. If the whale is dead, the team determines if it’s beached or which beach it could be towed to in order to perform a necropsy. A necropsy is not something elected officials look forward to in beach communities, particularly during summer months when tourists are around. Necropsies involve very sharp knives, pounds and pounds of whale innards, and heavy construction equipment to drag the carcass and later bury it on a beach.

The team looks for propeller strikes, abrasions, and signs of blunt force trauma, such as broken bones, to try to determine what may have caused the whale’s death. Still, many could have been struck after they died. And some whales, Barco says, show signs of healed wounds, suggesting they survived a ship collision or entanglement with fishing gear. If possible, the team also runs tests to evaluate overall health, checks for exposure to pathogens, and also examines the whale’s stomach contents. The scientists are also searching for signs of underlying illness.

“There are things that you can infer, but it is less than precise, and when you throw decomposition on top of that, many times it is guess work,” she says.

Prevention is Difficult

Preventing vessel strikes requires both a deeper understanding of whale biology and deeper awareness of whales from people piloting vessels. NOAA has enacted vessel speed restrictions to protect specific species of whales, such as the endangered North Atlantic right whale, which would also serve to protect other whales. NOAA requires 65 feet or longer to travel 10 knots or less in certain locations, called seasonal management areas. One of those areas is the mouth of Chesapeake Bay.

“Prevention is really tough. First of all, a whale has to detect a vessel. Then it has to perceive it as a threat. And then it has to take appropriate action,” Barco says.

Whales Team Up in Amazing Bubble-Net Hunt

In the summer, southeastern Alaska's waters teem with humpback whales that have migrated north to feed on herring and other fish. One of their most fascinating behaviors is bubble-net feeding, a complex and coordinated tactic for capturing many fish at once.

The whales can certainly hear the ships, says Doug Nowacek, professor of marine conservation technology at Duke University, but other factors could be in play. Nowacek, who studies the behavior and acoustic ecology of whales and dolphins, says the animals could be distracted by feeding or the constant drone of shipping traffic. There’s been discussion of acoustic warnings ships could employ, something akin to deer whistles used by motorists, but Nowacek says there’s little guarantee they would work.

“As far as they are concerned, they are the biggest thing in the ocean. An adult humpback has no real fear of anything, so why should it have any reason to think some new, loud sound would be anything other than a new, loud sound?” he says. “You’re basically talking about training a whale to adapt to sound, and with whales, it’s usually they get hit once and that’s it.”

A spokesman for the Port of New York and New Jersey, the third largest port in the country, referred questions about whales and vessels interaction to the Coast Guard, which has jurisdiction over the shipping lanes. The Coast Guard enforces rules set forth by NOAA for all boaters, a spokesman said. Vessels must stay 100 yards away from any marine mammal and put engines in neutral when whales approach. Every boater is required “to report when they see endangered whales or whenever they strike a whale.”

New York, according to NOAA, had the most stranded humpbacks in this recent unusual mortality event with 17. Virginia and Massachusetts followed. Researchers say strandings are nearly always fatal, aside from the rare moments when a whale trapped in gear can be freed and is healthy enough to swim off and recover.

Rob DiGiovanni, founder of the Atlantic Marine Conservation Society, a Long Island volunteer organization that responds to strandings, says he’s seen increased numbers of menhaden, the whales’ preferred food source, close to inshore shipping channels. These channels have become “rest stops,” DiGiovanni says, where whales stop and refuel.

“Let’s at least be aware that they’re out there,” DiGiovanni says. “We all drive slower in a school zone, and this isn’t a major impact in our lives. It’s for the good of the animals.”

Three whales have stranded so far this year, according to NOAA, including one in Virginia. All three animals were dead.

On the Atlantic Explorer, Sedaca follows every NOAA guideline, moving away from surfacing humpbacks after a certain time or idling the ship’s engine if they get close. Fresh photos of every distinct dorsal fin are taken to Alexis Rabon, the aquarium’s boat programs coordinator, and she checks them against a database of known whales.

“They’re typically solitary, so when they come through our area, it’s not abnormal just to see one,” she says. “But something that we’ve seen from a few of these individuals, such as the pair we saw yesterday, is that they’ve kind of been joining up with other animals.”

One juvenile whale, Rabob confirms, was seen twice, earlier in January and also that morning. While a local whale watching boat and a recreational boat lingered on the surfacing whale, Sedaca pointed the Atlantic Explorer north toward another reported whale spout in the shipping channel. Costidis said Delaware Bay’s shallow waters almost funnel whales into the deeper shipping channel.

Costidis said the only immediate remedy—less vessel traffic—is “not realistic” but slowing them down could help.

“To some degree,” he said, “dense shipping traffic will likely never be compatible with life for near-shore metropolitan whales."