PLYMOUTH (CBS) – Environmental officials were monitoring a juvenile short-finned pilot whale that was spotted swimming around Plymouth Harbor on Monday.

Pilot whales typically travel in pods of 10 to 50 whales. This particular animal appeared to be alone.

Experts at the New England Aquarium say they are particularly concerned about the whale’s health.

WBZ-TV’s Jim Armstrong reports

While long-finned pilot whales are common in New England waters, aquarium spokesperson Tony LaCasse says the short-finned pilot rarely travels north of New Jersey.

Last week, a short-finned pilot whale died after beaching itself in Duxbury.

Days later, another one beached and died in Truro.