Our team cared for three rescued seals this season: a harp seal that was released back to the ocean, and two other seals that unfortunately passed away, despite our team's best efforts to save them.
On April 4, 2023, onlookers gathered on the beach in Ocean City, Maryland, near 41st Street to cheer on a juvenile harp seal as he scuttled his way through the sand and into the ocean. Five weeks prior, this same seal had been spotted by the Marine Education, Research and Rehabilitation (MERR) Institute in nearby Rehoboth Beach, Delaware, showing signs of distress.
He was rescued by our partners at MERR and transported to Baltimore for treatment on February 28. The seal—nicknamed Prince in line with our musician naming theme—was dehydrated and malnourished when he was admitted to our Animal Care and Rescue Center.
Dehydration is unique to harp seals like Prince because these animals are known to be stress eaters. They consume snow and ice when they're in the Arctic; on mid-Atlantic beaches, they begin to eat sand and rocks instead. The warmer temperatures in the region also mean that these seals become dehydrated more easily than they would in the Arctic.
According to our team, Prince was a textbook case: he needed electrolytes to treat his dehydration, and he needed to gain weight. When he was rescued, he weighed only 42 pounds. After eating an impressive 14 pounds of fish every day, he weighed a healthy 55 pounds when he was cleared for release.
Prince's rescue, rehabilitation and release was a resounding success, but not all rescue stories end as happily as his. Earlier this year, our team was reminded of this reality with two rescued seals that briefly came into our care before passing away, despite our team's best efforts to save them.
The first case was a harbor seal with a traumatic flipper injury that was spotted in the Virginia portion of the Chesapeake Bay by our peers at the Virginia Aquarium. The seal, whose left rear flipper was almost completely severed from a boat strike, arrived at the Animal Care and Rescue Center on Friday, April 14. Our team knew that the seal's only chance of survival was to amputate the flipper. It was an extremely high-risk surgery given his weakened condition, and he did not make it.
There are always risks associated with anesthesia, even in the healthiest animals. "Unfortunately, in cases like this, it's not ideal to take an animal that's unstable and put it in surgery—but it was his only chance, and we knew we had to give it a try," Director of Animal Rescue Jenn Dittmar explained.
Later in April, our team admitted another seal patient: a grey seal pup that stranded on Assateague Island National Seashore and arrived in our care underweight with an eye abrasion, gastrointestinal parasites and symptoms of a respiratory infection, which our team believed to be a lungworm infection. Lungworms in young seal pups can be fatal and are difficult to treat.
Despite his symptoms, the results for the fecal test typically used to diagnose lungworms did not show those parasites. A radiograph showed signs of pneumonia, and while our team kept an eye on his respiratory issues, they began treating his gastrointestinal parasitic infection. As the treatment for his parasites began to kick in, his condition appeared to improve; he was eating well and beginning to gain weight.
The seal appeared more lethargic than normal about two weeks into his rehabilitation, but this isn't unusual with the type of medication he was receiving to treat his parasites. One day, about 30 minutes after hauling out from the pool in his enclosure, he began having a seizure. Seals can be prone to seizures, particularly when they have an infection. Although our team did everything in their power to stabilize him, he passed away.
These cases are just two examples of a huge shift in the population of rescued seals that our team has cared for in recent years. Ten years ago, a standard rescued seal was a harbor seal with medical issues that were relatively easy to treat; they were typically underweight with mild respiratory infections. Over the past five years in particular, this has changed dramatically.
In the northwest Atlantic, the population of grey seals has steadily pushed the population of harbor seals out of their traditional range. This trend seems to be moving south along the coast, as 15 years ago, rescue organizations in New England were seeing this same population shift. After that, the Long Island area began to see more greys than harbors, and now our team in the mid-Atlantic is consistently caring for more sick grey seals.
This is due in part to the establishment of a grey seal rookery off the coast of Cape Henlopen, Delaware. As a new herd has emerged from this rookery, our team is seeing more pups than ever before; the grey seal pup who was in our care this season was only two months old. These younger seals come with a whole new set of medical issues and needs.
"These seals are smaller and younger, with more complex medical problems, than those we were seeing in the past," Senior Rehabilitation Biologist Margot Madden explained. "Serious infections, like lungworm and ear infections, can be detrimental for these young pups that don't have fully formed immune systems."
This shift in the regional seal population has resulted in cases that are much more challenging for our team to treat, but they're learning as much as they can from experience and collaboration with colleagues in other regions. The future of the changing seal demographic in the mid-Atlantic—and how it will continue to impact the seals in our care—may be unclear, but one thing is for certain: Our team remains committed to saving every seal that comes through our doors, no matter how challenging the case may be.
All National Aquarium stranding response and seal rehabilitation activities are conducted under NOAA permit 18786-04.
