The Bay’s Other Beautiful Swimmer
Humans aren’t the only mammals swimming in the summer Bay. Dolphins are making regular visits, too.
From April to September, these sleek swimmers are being spotted from Virginia’s Northern Neck into the Potomac River and up all the way to the Inner Harbor of Baltimore.
Over 1,400 ballots were cast in the Potomac-Chesapeake Dolphin Project’s contest to name two new adult visitors — newly called Mac for Potomac and Chessie — being tracked in the Vir-Mar Beach area just above the Virginia-Maryland border.
The majority of these visitors are bottlenose dolphins (Tursiops truncates). The exception was the Risso’s dolphin spotted in early May in the Inner Harbor. The National Aquarium reports that guest was the first of its kind anyone recalled seeing in the harbor. Unfortunately the Risso’s died several weeks later, says Amanda Weschler, stranding coordinator for Maryland Department of Natural Resources.
The sightings begin as early as January, says Weschler. “We easily get thousands of reports of bottlenose dolphins each year.”
The Appeal of the Bay
What are they doing here? Is it cause for concern?
Not really, says Helen Bailey, researcher and dolphin specialist at the Chesapeake Biological Laboratory in Solomons. The presence of bottlenose dolphins has been noted as far back as the 1800s.
“The bottlenose dolphin is a coastal species, and there are actually a number of different populations that visit the Bay each year,” Bailey says. “They can handle shallow water, and they aren’t affected by changes in salinity like other species.”
Bailey, who has been fascinated with dolphins since she was a teenager, says she was surprised that the animals hadn’t been studied much in the Bay.
“When I came to Solomons, I asked people if they saw dolphins, and all I heard was an occasional report. I never saw them, and many people believed they were just an occasional visitor to the Bay.”
Thanks to research using hydrophones — underwater microphones — she discovered that dolphins were frequent guests and especially active at nighttime.
To better understand the behavior and patterns of bottlenose dolphins, Bailey and her team created a website and mobile app called DolphinWatch. It invites Chesapeake boaters, paddlers and beachgoers to log their dolphin sightings on a map, with date, location and timestamp, and to share video and photos.
Scientists like Bailey believe that dolphins come to the Bay for feeding, mating and calving.
“Dolphins are opportunistic eaters. They may not be dining on just one thing,” she says. “We have photos of them eating anchovies, striped bass, menhaden and shad. Some of them even seem to develop a taste for a particular food.”
Dolphins can grow up to 12 feet long and almost 400 pounds. They’re also speedy, swimming more than 18 miles an hour. Covering a large swatch of the Bay is all in a day’s work for them.
They form large pods for protection, and they communicate through a complex system of clicks and whistles, making up to 1,000 sounds per minute.
DolphinWatch reported nearly 1,000 sightings in the first six months after it launched in summer 2017. Last summer, there were 800 confirmed sightings. Bailey’s team works to validate each sighting, from every corner of the Bay. That task gets exponentially harder with more reports coming in.
“We are just coming up on two years of data, but anecdotally we are hearing from people that they are seeing more dolphins, more often and in more places.”
Those numbers are expected to increase. After an epidemic that hit hard in 2013, the Atlantic bottlenose population is rebounding.
So why does it come as a surprise when we happen to catch that telltale dorsal fin breaking the surface?
“The Bay is a big place, and the chances that we will see a dolphin are small,” Bailey says. “But when we do, it’s a delight and a reward to see them. They are just amazing animals to watch. These social animals just exhibit incredible behaviors.”
Does the booming dolphin population mean more marine mammals are on their way to the Bay?
“If we see something like more manatees in the Bay, that’s a sign that water temperatures are rising and that’s a bad thing. But there is a likelihood that we will start seeing more whales here. The humpback whale population is on the rise, and that may mean there’s a chance that a whale or two will eventually find its way into the Bay.”