About 40 dolphins, which apparently took an unorthodox detour on their spring journey up the Atlantic coast, were spied yesterday visiting the Choptank River near Cambridge.
Armed with binoculars and cameras, a group of astonished spectators counted the dolphins as they swam past about 200 yards off the Horn Point Environmental Laboratories.
"It was kind of impressive. They took about an hour to pass by," said Wayne Bell, vice president for external affairs for the University of Maryland's Center for Environmental and Estuarine Studies, which operates the laboratories. "They didn't appear to be distressed. They weren't on their sides."
Dolphins are rarely seen that far up the bay, although they are fairly common at the mouth of the James and York rivers in Virginia in the summertime, according to James G. Mead, the Smithsonian Institution's marine mammal curator.
Mr. Mead and Valerie Chase, a staff biologist at the National Aquarium in Baltimore, said the dolphins were believed to be American bottlenose, the same species as the "Flipper" of TV fame.
They speculated that the dolphins were out in search of food. "There may be some good resource out there that has them turned on," Ms. Chase said, suggesting that they may have followed a large school of fish, perhaps menhaden.
Have the dolphins strayed so far that they are now lost?
When Mr. Bell last saw the dolphins, they were headed straight for the mouth of the Choptank River -- the right direction if you are trying to get out of the bay.
But he was worried. "My personal concern is that if they think they are migrating, they might head north when they get to the mouth of the Choptank," he said. That would send the dolphins toward the Bay Bridge and an eventual dead end at the Susquehanna River.
Ms. Chase and Mr. Mead are betting they will make their way out.
"Bottlenose dolphin are pretty wily animals and are fairly good at navigating in complicated situations," Mr. Mead said.
Spectators and experts agree that man should not intervene in the dolphin travels unless an animal becomes sick or stranded. It would be practically impossible to herd 40 or 50 dolphins out of the bay, Ms. Chase said.
There have been only two other sightings of bottlenose dolphins north of the Rappahannock River in the past 15 years and both occurred last summer, according to Mr. Mead, who keeps records of the sightings.
Last July 30, about 45 bottlenose were seen two miles north of James Island in the Little Choptank River. If the upper bay sightings continue for another year, he said, it could be evidence that the animals' habitat is changing.