In her youth, Blue was a standout mine-hunter for the U.S. military. She and her colleagues are now at the vanguard of geriatric marine mammal medicine.
 

By Emily Anthes

Photographs by Gabriella Angotti-Jones

SAN DIEGO — White caps were breaking in the bay and the rain was blowing sideways, but at Naval Base Point Loma, an elderly bottlenose dolphin named Blue was absolutely not acting her age. In a bay full of dolphins, she was impossible to miss, leaping from the water and whistling as a team of veterinarians approached along the floating docks.

“She’s always really happy to see us,” said Dr. Barb Linnehan, the director of animal health and welfare at the National Marine Mammal Foundation, a nonprofit research organization. “She acts like she’s a 20-year-old dolphin.”

But at 57, Blue is positively geriatric, one of the oldest dolphins in the U.S. Navy Marine Mammal Program. So the doctors had come to check on her heart.

Dr. Linnehan unpacked a dolphin-friendly electrocardiogram and bent over the edge of the dock, where Blue had surfaced. Then she carefully pressed four rubber suction cups, each containing a Bluetooth-enabled electrode, onto the dolphin’s slippery skin.

Dr. Linnehan wiped the rain off her tablet and studied the screen. “That’s her arrhythmia there,” she said, pointing to an oscillating wave marching across the display. The team first detected the irregular heartbeat several years earlier and had been monitoring it ever since.

“What we are looking for is: Are we getting to a place where we need to start talking about intervention, like a pacemaker or medication,” Dr. Linnehan said. No one had ever put a pacemaker in a dolphin before, she noted, but “we’re willing to cross that bridge if she gets to that point.”

For more than half a century, the Navy has run its marine mammal program from this base on the rocky Point Loma peninsula, training bottlenose dolphins and California sea lions to locate underwater mines, recover submerged objects and intercept rogue swimmers.

In that time, marine mammal medicine has advanced enormously, in part as a result of the Navy’s research. Consequently, the program’s veterinarians find themselves caring for an increasingly aged population of animals. “We’re just seeing things that we weren’t necessarily seeing decades ago, conditions that are associated with old age,” Dr. Linnehan said.

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On a misty day, three workers with the marine mammal program walk along a network of floating docks at Naval Base Point Loma in San Diego, while a fourth kneels and reaches into the water to greet a dolphin. The Marine Mammal Program at Naval Base Point Loma in San Diego.
On a misty day, three workers with the marine mammal program walk along a network of floating docks at Naval Base Point Loma in San Diego, while a fourth kneels and reaches into the water to greet a dolphin.

Dr. Barb Linnehan, the director of animal health and welfare at the National Marine Mammal Foundation, in green-brown hat, gave Blue a dolphin-friendly electrocardiogram.

So, in collaboration with researchers who study wild dolphins and with experts in human medicine, Navy scientists are now delving into geriatric marine mammal medicine. The pursuit could pay dividends not only for the Navy’s animals but also for wild ones — and, perhaps, even for people.

It could be the final frontier for the program, which is likely to leave a rich but ethically complicated scientific legacy. The Navy plans to phase out the program in the coming decades, said Mark Xitco, the program’s director. It has already stopped breeding dolphins and has turned some of their tasks over to underwater drones, he said.

In the years ahead, as the marine mammals are gradually replaced by technology, the animals will become less of a military asset and more of a scientific one.

“They will continue to serve the nation as that population of federal marine mammals that can be a resource for science,” Dr. Xitco said. He added, “Until, someday, we’re gone.”

When Navy scientists began working with their first dolphin, in 1959, they hoped simply to imitate it and learn how to design more hydrodynamic torpedoes. But marine mammals proved to have talents — deep-diving skills, keen underwater vision and, in some cases, top-notch sonar — that neither humans nor machines could match. So the Navy began training the animals to perform underwater tasks, deploying them in Vietnam, the Persian Gulf and elsewhere.

Technically, the marine mammal program was classified until the early 1990s, but it was a “pretty poorly kept secret,” Dr. Xitco said. Navy scientists helped create, and were heavily involved in, organizations for marine mammal researchers, he said, but “could neither confirm nor deny that we actually worked with the animals.”