Publisher Health

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.

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.”

Early morning exams

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.”

Today, 77 dolphins and 47 sea lions are part of the program, which is managed by the Naval Information Warfare Center Pacific and has an overall required budget of $40 million this year. About 300 people keep the program running. (Many are contractors; the National Marine Mammal Foundation, which was founded by several of the program’s veterinarians, helps provide veterinary care for the animals, for instance.)

The work often begins before dawn, when the yellow-hatted interns arrive at the “Fish House” to prepare meals for the animals. One morning last November, just after 6 a.m., the interns were busy sorting through sinks full of frozen herring, capelin and squid; pressing vitamins into the gills of a few still-icy fish; and portioning the seafood out into insulated buckets.

The buckets were then hauled out onto a pier jutting into San Diego Bay. Rows of floating docks crisscrossed the dolphins’ underwater enclosures. Trainers began tossing out breakfast and performing quick tip-to-tail checkups. The dolphins have been trained to cooperate, presenting their various body parts — teeth, belly, flukes — while their trainers give them the once-over.

Keeping the animals healthy is a critical part of the job, said Dr. Eric Jensen, the senior scientist for animal care. “You can’t go find mines, and you can’t go find bad people if you don’t feel good,” he said.

But the program’s veterinarians repeatedly note that they feel an ethical obligation to provide top-notch health care. Their affection for the animals is obvious, and Dr. Jensen — who joined some of the marine mammals on a 2003 deployment to Iraq — said that being part of the program was less a job than a lifestyle. He and his colleagues frequently refer to the animals as partners or teammates.

The animals have not volunteered for this life, however. In the program’s earlier years the Navy took dolphins from the wild. Although that practice ended decades ago, the program continues to draw criticism for keeping intelligent animals in captivity and conscripting them into human war efforts.

“I am not in favor of keeping dolphins the way they do for the purposes that they do,” said Lori Marino, an expert on cetacean intelligence and president of the Whale Sanctuary Project, who visited the program and became friendly with some of its researchers early in her career.

The Navy’s dolphins do have opportunities that are not afforded to some other captive dolphins, such as open-ocean swimming sessions, and they are clearly highly valued, said Janet Mann, a marine-mammal scientist and behavioral ecologist at Georgetown University. “The Navy has obviously perfected how you can keep a large number of dolphins in captivity with very high survival,” she said. Still, she added, “The dolphins don’t have agency like they do in the wild.”

Dr. Xitco said that the animals have only been used for defensive purposes and that none have ever died in combat. But some details about the animals’ capabilities and assignments remain tightly held. (Although officials granted The Times permission to name Blue, they requested that the other animals’ names not be disclosed.) A two-day tour of the facilities last fall was closely chaperoned.

“I guess in theory there could be some other program around the corner that I’m not going to show you, where we’re doing things that you wouldn’t be comfortable with or others wouldn’t be comfortable with,” Dr. Xitco said. “That’s not the case.”

After completing Blue’s exam, Dr. Linnehan and her colleagues trudged back up the hill to their offices, the chatter of dolphins and sea lions fading behind them. But even indoors, it was impossible to escape the animals’ presence: There were photos of dolphins, dolphin cartoons and a plushy toy sea lion. Anatomical models of dolphins sat on numerous desks.

The laboratory, located just a short walk away, is typically bustling after the animals’ morning medical checks, as technicians process any recently collected blood, urine, fecal or other samples. Later, the samples are stored in a small, windowless room across the street, where supercold freezers contain a marine-mammal biobank that dates back decades. “We’ve got animals here in their 50s,” Dr. Xitco said. “All their health records are upstairs, and their tissue samples are across the street. It’s just an amazing resource.”

This biobank has made it possible for scientists to do longitudinal studies, charting, for instance, how dolphins’ blood chemistry changes as they age. And the large, well-trained animal population allowed the Navy to pioneer new medical techniques, such as portable ultrasounds for dolphins. Dr. Sam Ridgway, who was the program’s first veterinarian and continued to publish new research until his death last year, became known as the father of marine mammal medicine. To date, research on the Navy’s animals has yielded more than 1,200 scientific papers, conference presentations and book chapters, Navy officials said.

“No question they have been a leader in terms of developing our understanding of dolphin medicine,” said Randy Wells, who directs the Chicago Zoological Society’s Sarasota Dolphin Research Program. (Dr. Wells frequently collaborates with the program’s researchers and has also received funding from the Navy.)

After their morning exams, the animals have training or enrichment sessions, often in the open ocean, where their athleticism is on clear display. The dolphins swim alongside boats, retrieve brightly colored balls, launch themselves into the air, slip under the water’s surface and reappear in a flash.

Dolphin day afternoon

But they do slow with age, Dr. Jensen said. Their energy levels flag, their joints stiffen and they put on some extra pounds. Some develop heart disease, kidney stones or vision problems, which can require surgical intervention.

A few hours after examining Blue, Dr. Linnehan joined her colleagues at the Marine Mammal Surgical Center to talk through some upcoming cataract surgeries for sea lions. The team has become more proactive, said Dr. Jenny Meegan, a senior veterinarian at the National Marine Mammal Foundation. The veterinarians now perform cataract surgery before the animals’ vision deteriorates significantly, she said, and are studying new diets that they hope will prevent dolphins from developing kidney stones.

“We want to give them the best health care, the best lives,” Dr. Meegan said. “What we can learn from them lives on by being able to help animals in the future.”

Blue is the program’s paragon. Focused and seemingly tireless, she was once one of the Navy’s star mine hunters, earning a Navy Achievement Medal for her efforts, according to Dr. Xitco. But when she unexpectedly became pregnant in her 30s, she stopped searching for mines and began participating in acoustics research instead, which remained her primary role as she aged.

When Dr. Linnehan and her colleagues set out to create better ways to conduct cardiac assessments of dolphins, they tapped Blue to participate. Working with Blue and other Navy dolphins, the researchers developed a method for performing comprehensive cardiac exams on stationary dolphins while they were in the water. In the process, they discovered that Blue had a previously undetected arrhythmia.

It was not the only surprise. The team, partnering with other researchers, went on to perform heart exams in the wild, on dolphins in Sarasota Bay in Florida and Barataria Bay in Louisiana. “A lot of them had murmurs,” Dr. Linnehan said, “which nobody had described before.” The scientists also found that a variety of cardiac abnormalities were especially prevalent in the Barataria Bay dolphins, which had been heavily exposed to oil after the Deepwater Horizon oil spill in 2010.

The Navy’s dolphins have frequently served as pioneers, allowing scientists to develop and test new techniques before they take them into the field, where “the opportunities to examine the animals are much more rare and much more precious,” said Dr. Wells, who collaborated on the studies.

Now, Dr. Linnehan is working with a biotech company to build an electrocardiogram harness that Blue can wear while freely swimming, diving or sleeping, a tool that might eventually help scientists study the hearts of wild dolphins under more natural conditions. “This would be a huge wealth of information that nobody’s gotten before,” Dr. Linnehan said.

Myriad other projects are underway, including the development of an acoustic monitoring system to detect the sounds of dolphins in distress, and a low-gravity surgical table, to better replicate the dolphins’ marine environment. (On land, the tug of gravity can compromise the animals’ heart and lung function.) Researchers recently devised a ventilator specifically for marine mammals, which have unique styles of breathing.

Surgical tools like these would be useful for the sick and injured animals that sometimes wash ashore with flipper injuries, fractured jaws or even gunshot wounds, said Dr. Cara Field, the medical director of the Marine Mammal Center in Sausalito, Calif. And a better understanding of what is and isn’t normal for marine mammals throughout their long life spans could help in evaluating the wild animals that appear without a detailed health history, she added. “When they wash ashore with disease or injury, we only get them at one point in time when they’re sick,” Dr. Field said.

Some of the research might even benefit humans. “Older dolphins age a lot like older people,” said Dr. Stephanie Venn-Watson, a veterinary epidemiologist who was previously a researcher at the Navy program and the National Marine Mammal Foundation.

In a series of studies, Dr. Venn-Watson and her colleagues found that aging in dolphins was associated with some familiar conditions, including chronic inflammation, high cholesterol and anemia. And despite their similar diets and environments, different Navy dolphins seemed to age at different rates; fast-aging dolphins experienced especially pronounced declines in hemoglobin, the oxygen-carrying protein in red blood cells.

The team also identified two compounds in dolphin diets — odd-chain saturated fatty acids known as C15:0 and C17:0 — that were associated with better health, including higher hemoglobin levels.

(Dr. Venn-Watson is now the co-founder and chief executive of Epitracker, a biotech company that has ongoing collaborations with the Navy, and Seraphina Therapuetics, which sells C15:0 supplements.)

The findings have caught the attention of experts in human medicine, including Dr. Jeffrey Schwimmer, a pediatric gastroenterologist at the University of California, San Diego, who started his own studies on the compounds. These fatty acids, which have shown promise in other early studies, are also being investigated elsewhere. But, Dr. Schwimmer said, “It was the dolphin work that put it on my radar.”

Other scientific teams have reported that dolphins can develop brain lesions that look similar to those in people with Alzheimer’s. Now, the Navy’s researchers are working to determine whether dolphins also experience similar cognitive symptoms. If they do, it might explain some marine mammal strandings, experts say, and could make dolphins a useful model for Alzheimer’s.

“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,” said Ailsa Hall, an emeritus professor of marine biology at the University of St. Andrews.

The Navy also has a wealth of new data to mine, including the newly sequenced genomes of about 70 of the program’s dolphins, and it is partnering with Dr. Venn-Watson’s company, Epitracker, to look for genetic and metabolic predictors of health and disease. The priority is finding ways to improve the animals’ lives, Dr. Jensen said. But “if you can take it and have a spin off benefit for human health care, it’s a win-win,” he added.

Into the sunset

Not all experts feel that way. The Navy has done some “really interesting, cutting-edge” research, Dr. Marino acknowledged. But some of its studies have also been “pretty unpalatable,” she said, pointing to one that made dolphins ingest seawater. Even a noninvasive imaging study requires an animal to leave the water and travel to a medical facility, she noted.

“These are all things that a dolphin is not interested in really doing and do not make their life worthwhile,” said Dr. Marino, who used to conduct research on captive dolphins before becoming uneasy with the practice.

Dr. Xitco said that he and his colleagues adhere to animal welfare and research regulations and make “every effort possible” to minimize negative effects on the animals. But sometimes the studies do require blood draws or milk samples or biopsies or brief exposure to noise. In those cases, he said, they have made the calculation that mild, temporary discomfort is outweighed by the value of the research. “We are the control population for the world of marine mammal medicine,” he said.

(Although it is beyond the scope of the marine mammal program, some experts also noted longstanding concerns about how the Navy’s broader suite of ocean activities, including its use of sonar, might affect wild marine mammals.)

Cutting-edge research is happening with wild dolphins, too, scientists said. But studies of captive animals are an important complement, said Austin Allen, a marine mammal scientist at Duke University. “There’s synergies between the two,” he said. “There’s just types of data that we can’t collect in the wild.”

Since the marine mammal program began, public affection for marine mammals has grown, experts said, and scientists have learned much more about how sophisticated dolphins are and what they need in order to thrive — in part because of the Navy’s research.

And when the sun does set on the marine mammal program, the world may never see another collection of animals quite like it. “There’s just no population like it in the world,” Dr. Venn-Watson said, “and it will not happen again.”