These dolphins were photographed near the mouth of the Potomac River where it empties into the Bay. (Potomac-Chesapeake Dolphin Project, taken under NMFS Permit No. 19403)This spring, when pods of dolphins crossed the threshold into Chesapeake Bay waters, the scientists were ready for them.

The dolphin tracking website that went online in June 2017 was already up and running for the season, ready to record as early as the end of April that a few Atlantic bottlenose dolphins had arrived near Cove Point.

By mid-May, participants logging onto the Chesapeake Dolphin Watch website, run by the University of Maryland Center for Environmental Science, had reported 16 dolphin sightings in Bay waters in places as far north as Shady Side and Dundalk, MD. Researchers hope to see that number grow throughout the summer as more people become aware of the popular creatures’ presence.

Since the site launched last summer, dolphin-watchers have used it to report 1,000 sightings throughout the Bay and its rivers. The crowd-sourcing project blew researchers’ expectations — that maybe a few dozen dolphins frequented these waters in the summer — out of the water.

“We knew anecdotally that dolphins were seen in the Chesapeake, but I still wasn’t anticipating anything like the number of sightings we’ve seen reported,” Helen Bailey, an associate research professor at UMCES Chesapeake Biological Laboratory, said last year. “It’s just been incredible.”

Bailey has been studying dolphins in the Patuxent and Potomac rivers with underwater microphones, called hydrophones, to better understand what causes them to travel. But she and her team wondered where else dolphins were wandering in the Bay. That inspired the crowd-sourced website, which will launch a mobile application later this month.

While dolphins frequent the Lower and Middle Chesapeake Bay and southern coastline of Virginia in the summer, they were not often seen venturing into the Bay’s rivers until recent years.

The apparent return of dolphins to the Potomac interests scientists who see their presence as a good omen for local water quality. Historic accounts indicate that the creatures once swam as far north as the Aqueduct Bridge near Georgetown University in the District of Columbia.

The local crew of dolphins began capturing more media and public attention in 2016 after Georgetown University researcher Janet Mann began studying how far they were venturing into the Potomac and other Bay tributaries. That research, along with reports from local citizens, indicates that dolphins are traveling farther and in greater numbers, but scientists are still trying to understand why and to what extent.

Mann, who has spent three decades studying dolphins in Australia’s Shark Bay, is continuing to study a local population of more than 500 individual dolphins spotted near the mouth of the Potomac as part of the Potomac-Chesapeake Dolphin Project, which was started by the Georgetown researcher. The team has named many of them after U.S. presidents and first ladies.

Mann kicked off this year’s dolphin-spotting season with an editorial in The Washington Post and last year published a book about the behavior of cetaceans, a family that includes dolphins, called Deep Thinkers: Inside the Minds of Whales, Dolphins, and Porpoises.

In the book, Mann points out that much of the current research about these marine mammals has been gleaned from studying them in captivity. But, as the public has soured on the spectacle of sea creature shows at theme parks — and the sentient creatures have gained increasing legal protections since the 1960s — more research in natural settings is under way.

As part of that trend, seven dolphins located at the National Aquarium in Baltimore could soon be relocated to a seaside sanctuary in Florida, according to the Associated Press. The aquarium has begun a three-year program, including raising water temperatures in the dolphins’ indoor tanks, to teach the mammals new behaviors and prepare them to move.

“The species we exploited so heavily for centuries now command our attention,” Mann writes in the book’s introduction.

This summer, the species — in the wild — could continue to captivate Chesapeake Bay audiences, who are just beginning to realize that they might spot a dolphin breaching near Baltimore.    

Last year, people used the tracking website to report dolphins as far north in the Bay as the Magothy River and off Hart-Miller Island east of Baltimore, with several other sightings just west of Rock Hall on Maryland’s Eastern Shore. Bailey said she tries to follow up on the reports and was able to verify about 450 of those sightings.

The northernmost confirmed sightings in the Potomac last summer were near the Gov. Harry W. Nice Memorial Bridge, where U.S. Route 301 crosses the river just south of Popes Creek, MD. The Dolphin Watch map, which can be viewed by creating an account on the site, recorded a couple of citizen sightings there on the morning of July 4, and at least one more after that.

The updated website now allows contributors to add photos and videos to their reports and include descriptions about whether they spotted the creatures from a boat or shoreline and other relevant details. Camera icons will appear next to the dolphin images on the site’s map to indicate where sightings have been confirmed.

Ann-Marie Jacoby, a field investigator who worked on the Potomac-Chesapeake Dolphin Project last year, said she hoped the dolphin would become a flagship species of the Bay. But she didn’t imagine how quickly they’d become popular with boaters and beachgoers who helped spread the word.

“We wouldn’t be able to find out [about their presence] so quickly if it hadn’t been for the public reaching out and being so interested,” Jacoby said.

To see where dolphins have been spotted so far, visit Learn about Mann’s research at