Dolphins might be more common and wide-ranging in the Chesapeake Bay than once thought, if recent reports from citizen spotters are any indication.

Since a Chesapeake Dolphin Watch website launched at the end of June, 1,200 people have signed up and reported more than 500 dolphin sightings, often of 10 or more of the mammals at once.

“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,” said Helen Bailey, a research associate professor at the University of Maryland Center for Environmental Science’s Chesapeake Biological Laboratory who helped to launch the website. “It’s just been incredible.”

For the last three years, Bailey has been using underwater microphones, called hydrophones, to study dolphin communications and whereabouts in the Bay. But her team’s pair of hydrophones in the Patuxent and Potomac rivers cover just the corners of the expansive water body — and they wondered where else the dolphins were wandering.

“We didn’t have good information about where else we should be putting the listening devises to learn more about the dolphins, and we really just need as many eyes on the Bay as we can get,” Bailey said, which inspired the crowd-sourced tracking app.   

Atlantic bottlenose dolphins captured media and public attention  last year when a researcher from Georgetown University began studying how far they were venturing into the Potomac River and other Bay tributaries. That research and reports from locals indicate dolphins are traveling farther into the Bay and in greater numbers than they have been in years, but researchers are still trying to understand why and to what extent.

Janet Mann, the Georgetown professor, has spent three decades studying dolphins in Australia’s Shark Bay. She and her team identified and counted about 500 individual dolphins in the last two years near the mouth of the Potomac as part of their Potomac-Chesapeake Dolphin Project.

While dolphins frequent the Lower and Middle Chesapeake Bay and the southern coastline of Virginia in the summer, they’re not often seen venturing into the Bay’s rivers. Their apparent return to the Potomac is of interest to scientists because historic accounts indicate they once swam as far north as the Aqueduct Bridge near Georgetown University in the District.

Some of the so-called Potomac dolphins, which the researchers named after U.S.  presidents and first ladies, have been seen returning to the same reaches of the river in recent years. The one dubbed Zachary Taylor, for example, was identified by researchers each of the last three summers, and Barbara Bush — a mama dolphin with two calves — has been back as well.

Ann-Marie Jacoby, a field investigator on the project and research associate at Georgetown, said these dolphins were counted with “very little effort” on outings once a month, “so I think there could be thousands.”

The Georgetown researchers already worked closely with Bailey and others studying Atlantic dolphin populations, and the team is monitoring the Dolphin Watch website closely to see where else the mammals are reported to be traveling in the region.

Others who’ve signed onto the tracking app have reported seeing 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 with reports on the site to confirm sighting times and locations. 

Jacoby said the northernmost confirmed sightings in the Potomac this summer are 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 in that area on the morning of July 4, and at least one more since then.

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

And many locals are eager to report their sightings. Bay Journal reader Michele Middleton sent photos of what she said was a pod of about 20 dolphins swimming in the Potomac near Westmoreland State Park in Virginia.

“They surfaced in pairs near our boat,” Middleton wrote in an email. “We stopped the boat and watched them for about 15 minutes. It was magical to watch them play.”

Jacoby has been so intrigued by the project that she plans to continue studying the dolphins’ presence in the Chesapeake as a Ph.D. student at Duke University in the fall. She’ll return, much like the dolphins do, for part of the summer to continue monitoring their behavior and to interview locals about how many dolphins they recall seeing.

“This area, the Bay and its estuary, may be very important for several bottlenose dolphin populations,” Jacoby said. “I would love for dolphins to become a flagship species for the Chesapeake Bay and Potomac River conservation efforts — and, by that I mean, a poster child.”

Citizens who spot dolphins in the Bay can record their sightings at and send photos to