Once Military Assets, Now Aiding Research
SAN DIEGO, California — White caps were breaking in the bay, but at Naval Base Point Loma, a bottlenose dolphin named Blue was impossible to miss, leaping from the water and whistling as a team of veterinarians approached.
“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 geriatric, one of the oldest dolphins in the U.S. Navy Marine Mammal Program. So the doctors had come to check her heart. Dr. Linnehan unpacked a dolphin electrocardiogram and bent over the edge of the dock, where Blue had surfaced. Then she pressed four rubber suction cups onto her slippery skin.
“That’s her arrhythmia there,” she said, pointing to an oscillating wave on her tablet’s screen. The team first detected the irregular heartbeat several years ago. “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.”
For over half a century, the Navy has run its marine mammal program from this base, 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, in part as a result of the Navy’s research, meaning the program’s veterinarians find themselves caring for older animals. So, in collaboration with wild dolphin researchers and with experts in human medicine, Navy scientists are delving into geriatric marine mammal medicine.
It could be the final frontier for the program. The Navy plans to phase it out in the coming decades, said Mark Xitco, its director. It has stopped breeding dolphins and has turned some of their tasks over to underwater drones.
When Navy scientists began working with their first dolphin in 1959, they hoped simply to design more hydrodynamic torpedoes. But dolphins had deep-diving skills, keen underwater vision and sophisticated sonar that neither humans nor machines could match. So the Navy began training them to perform underwater tasks, deploying them in Vietnam, the Persian Gulf and elsewhere.
Technically, the program was classified until the early 1990s, but it was a “poorly kept secret,” Dr. Xitco said. Today, 77 dolphins, 47 sea lions and about 300 people are involved.
Animal health is critical, said Dr. Eric Jensen, a senior scientist: “You can’t go find mines, and you can’t go find bad people if you don’t feel good.”
The veterinarians have obvious affection for the animals, which have not volunteered for this life. Early on, the Navy took dolphins from the wild. That ended decades ago, but the program is still criticized for keeping intelligent animals in captivity.
A marine-mammal biobank dates back decades, which has made it possible for scientists to do longitudinal studies, charting, for instance, how dolphins’ blood chemistry changes as they age. Research has yielded over 1,200 scientific papers, conference presentations and book chapters, officials said.
After morning exams, the animals have training or enrichment sessions. They swim alongside boats, retrieve balls and launch themselves into the air. But they do slow with age, Dr. Jensen said. Their energy levels drop, their joints stiffen and some develop heart disease or vision problems.
Blue was once a star mine hunter. When Dr. Linnehan and her colleagues set out to create better ways to conduct cardiac assessments of dolphins, they chose her to participate, and discovered an arrhythmia.
“Older dolphins age a lot like older people,” said Dr. Stephanie Venn-Watson, a veterinary epidemiologist who previously worked for the program. She and her colleagues identified two compounds in dolphin diets — odd-chain saturated fatty acids known as C15:0 and C17:0 — associated with better health, catching the attention of experts in human medicine.
Other teams have reported that dolphins can develop brain lesions similar to those in people with Alzheimer’s. Now, Navy researchers are working to determine whether dolphins also experience similar cognitive symptoms, which might explain some strandings, experts say, and could make dolphins a useful model for Alzheimer’s.
Ailsa Hall, an emeritus professor of marine biology at the University of St. Andrews in Scotland, said, “It’s really exciting from my perspective as a general marine mammal scientist to see these animals coming into their own as important models, if you like, that allow us to learn not only for their benefit, but also for the benefit of others.”