National Aquarium biologists were tracking a dolphin Thursday that appeared to be in distress in the Baltimore harbor.
The dolphin was spotted in waters between the Canton waterfront and Fort McHenry about 9:45 a.m., swimming in circles and flapping its tail “irregularly,” aquarium spokeswoman Jen Reardon said.
In an email Thursday night, Reardon wrote that the dolphin has been identified “as a Risso’s dolphin calf” and that a rescue effort is too risky.
“Due to the fact that the dolphin is free swimming in a deep, large body of water, attempting a rescue would be dangerous to both human responders and the calf,” Reardon wrote.
“With the nearest dolphin rehabilitation facility located in Florida, even if rescue were possible and successful, the calf would have to be transported a long distance, which would create additional stress for the animal.”
She added that officials will continue to monitor the situation, but “believe our best option is not to intervene at this time.”
The aquarium said Friday that the dolphin was last spotted around 6:45 p.m. Thursday night near the Baltimore Marine Center at Lighthouse Point in Canton.
“We cannot say if it has left the harbor,” the aquarium said in an email.
It is common for Atlantic dolphins to swim into the Chesapeake Bay but rare for them to make their way into Baltimore’s harbor.
The dolphin’s locations and behavior both concern aquarium biologists, Reardon said, but they have not confirmed what, if anything, is wrong with the animal.
More than 2,000 dolphin sightings have been reported to Chesapeake Dolphin Watch, a project of the University of Maryland Center for Environmental Science, since July 2017.
One was reported last month just off Fort McHenry, but otherwise, the closest any of the marine mammals have been spotted to Baltimore is the mouth of the Patapsco River.
Baltimore Sun reporters Phil Davis and McKenna Oxenden contributed to this article.