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A detailed look inside UNCW’s Marine Mammal Stranding Program

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UNCW Marine Mammal Stranding Program
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WHQR
A stranded dolphin.

The University of North Carolina Wilmington’s Marine Mammal Stranding Program responded to 100 strandings in 2021. WHQR visited their lab to find out why these animals wash up on the coast.

The UNCW program has responded to strandings involving 23 different species of cetaceans – or whales or dolphins. They also respond to strandings of marine mammals like seals and manatees.

A 'stranding' is a beaching of a live or dead marine mammal. According to Dr. Tiffany Keenan, the stranding coordinator at UNCW, North Carolina has “the highest number of strandings, per unit of length of beach, of any beach across the Atlantic coast.”

The state’s coast is a “really unique place as far as species diversity goes for marine mammals; it's a maritime jungle off of Cape Hatteras for sure,” said Keenan.

In the past, the research team at the Oriole Burevitch Laboratory, one of the only facilities of its kind on the east coast, has conducted necropsies on species like a juvenile Atlantic Minke whale, a giant manta ray, sharks, and, at one time, even an ostrich.

In order to do their work, their stranding truck features a crane that can lift an animal that weighs up to two tons. They have two large freezers kept at four degrees celsius to preserve specimens. And since the lab went online after it was constructed in 2011, the number of scientific collaborations and projects that Keenan and her team have been able to do has “just skyrocketed.”

They work with institutions such as the Duke University Marine Lab, N.C. State University, National Marine Fisheries Service, U.S. Coast Guard, and the North Carolina Aquarium at Fort Fisher, to name a few.

The necropsy of WAM 736

On May 11, WHQR visited the lab to view Keenan performing the necropsy of a one-year-old female bottlenose dolphin with four graduate students: Olivia Jackson, Jaquelyn Salguero, Alicia Cotoia, and Kristi Mitchell.

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Rachel Keith
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WHQR
Keenan, Mitchell, and Jackson in the lab.

The dolphin, known as WAM 736, washed up on Freeman Park in March 2020. Her body has been frozen since then.

“It's very rotund. It's as we call it, a fat sassy young animal that was just kind of going along living its life and made a bad decision and got caught in a net and died,” said Keenan.

Nets full of fish like spot or mullet – or even shrimp – can be tempting to a young dolphin.

“You see a fish essentially sticking out of a net, looks like a great idea to go try and get a free meal. What happens is those animals swim forward into the net, these guys can't swim backward,” said Keenan.

When WAM 736 washed up on shore, researchers found parts of the net around her body — although that type of evidence isn’t typically visible.

“And what you can see are these very distinct linear marks on the leading edge of the dorsal fin. And then you can also see some matching marks on the trailing edge, and you can see how the line — because it's abrasive — will actually cut through the tissue,” said Keenan.

Linear line patterns that are equidistant apart on a dolphin’s body, according to Keenan, are a red flag because they are so rare in nature.

But Keenan said the scientific community continues to advocate for changes like leaving nets out for a shorter time or having someone consistently checking to see if a dolphin's stuck.

“For the most part, we want to work with the fisherman. And we know that they want to mitigate the harm to the animals in their environment, but also the damage to their gear as well, which is costly to them,” she said.

Dolphin stranding death numbers

About 67% of the bottlenose dolphin stranding deaths are in some way a result of human interaction — whether it's from getting caught in a net, being struck by a vessel, or having a plastic bag stuck in their intestinal tract.

Olivia Jackson is a master’s student who has worked with the stranding program since August. All five of the strandings she’s responded to have been dolphins. She said not all of the deaths she’s seen are caused by humans — some are just nature taking its course.

“Some of them have been a little bit more indicative of just disease. My first one actually was an older dolphin. You could see that it was aging and just probably an old, old lady, and she actually got bit by a shark,” said Jackson.

That “old lady” could have been anywhere from 45 to 60 years old, a typical lifespan for a bottlenose dolphin.

Keenan said in North Carolina, an unusual dolphin mortality event happened between 2013 and 2015. It was caused by a virus, the Morbillivirus, which is similar to rinderpest in cattle or measles in humans. During the event, it’s estimated that about 50% of the bottlenose population on the entire East Coast died off.

“So it really ripped through the population; it was a dolphin pandemic,” said Keenan.

She said this is indicative of a cyclical event that happens about every 25 years, the one before 2013 was in 1987. That knocked out about half of the population, too.

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UNCW Stranding Program
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North Carolina bottlenose dolphin strandings by year. Note* 2013-2015 unusual mortality event (UME)

“So it seems like the population gets this certain capacity and that disease kind of reignites and knocks the population back down,” said Keenan. “But then the population afterward is extremely healthy. So from 2015 to about 2021, our standing numbers were down very low, but there was a time when we were having up to eight animals a day that were standing in our area.”

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Mean number of Tursiops truncatus (bottlenose dolphin) strandings per period in NC during and after unusual mortality event (UME).

The value of WAM 736's life

UNCW’s Dr. Ann Pabst, Dr. Keenan’s predecessor, along with Dr. Bill McLellan, developed and co-led the marine mammal stranding lab for 25-years. Pabst said even in retirement, she can’t stay away and dropped in to see the necropsy of WAM 736, named after the initials of her partner, William A. McLellan, who first responded to the dolphin’s stranding.

Pabst said it’s the lab’s hope that her death won’t be in vain.

“We do all that we can to ensure that we learn as much as possible from stranded individuals. And they are really, sometimes the only window into the lives of these animals. And the idea of being able to investigate these events, to be able to figure out how these animals are making their living, as well as what may have contributed to their mortality,” said Pabst.

Pabst said from the data that’s gathered from WAM 736’s body “in a sense, honors this individual, honors the species, and the honors the group of animals.”

After the necropsy, WAM 736’s flipper bones will go to researchers studying bone growth issues in humans. Other scientists will study her stomach organs to understand the number of microplastics she consumed, as well as her intestinal tract to evaluate the overall health of her microbiome.

Jacquelyn Salguero, a UNCW Ph.D. student who assisted with the necropsy, will be studying the parasites found within her body. Currently, researchers know only a little about how these parasites impact the overall health of a dolphin.

What to do if you witness a stranding

Dolphin Strandings & Who To Call

Importantly, not all strandings involve animals that have died. Sometimes the team can help with rehabilitation — and send animals back into the Atlantic. But if the team is going to be successful, Keenan said it’s so important that the public does not touch or help the animal before professionals can respond.

“We asked folks to do is to call us, rather than just pushing the animal back out, we can get a veterinarian out there to assess the animal. We can make decisions to see if that animal is a candidate for rehabilitation; we have partners that we work with for that,” said Keenan.

Unfortunately, if a dolphin has stranded, it’s likely dead — or close to it. But if the animal is still alive, Keenan said besides it being a federally protected species, the main reason for not pushing it back out to sea is that, “Sometimes it's just they're so debilitated they can't keep their blowhole above water, and they're just looking for a place to land to be able to breathe.”

Keenan said her team has access to specialized equipment like stretchers to prevent causing additional harm to the dolphin.

“Because these guys are not built like us, they don't have the same bone structure, their ribs are built to collapse, so when they dive they can push the air from their lungs. So when they are laying on the beach, they can't really support their own body weight because of those collapsible bones. So it's not the best thing for them to sit on the beach either. So those stretchers are just critical,” said Keenan.

If you see a stranded marine mammal, call 910-962-7266 or “if people don't know our number, they can just call 911, they know to call us. And that can be for dolphins, for whales for manatees and for seals, so any marine mammal,” said Keenan.

You’ll need the tell the first responder the location, the condition of the animal, and the type of species if known.