A juvenile humpback whale was spotted in the Boston Harbor on May 27, according to the The Boston Globe.

The animal, which was estimated to be between 20 and 30 feet long, was first sited around 8 a.m. by a whale watch boat about half a mile off shore near Logan International Airport.

Upon hearing the report, the Coast Guard and state Environmental Police set up a buffer zone around the whale in order to prevent any boats from hitting the animal that officials suspect may have been injured based on its thin appearance and apparently hurt tail.

In the end, however, Environmental Police simply escorted the whale out of the harbor, after which it swam away on its own.

The young whale may have been injured during its annual migration from calving grounds in the subtropical or tropical waters, such as the Dominican Republic, to their summer high-latitude feeding grounds, including the Gulf of Maine.

In fact, humpback whales undergo the farthest seasonal migration of any mammal, according to the National Oceanic and Atmospheric Administration (NOAA), the longest recorded journey including seven whales (including a calf) and stretching some 5,160 miles from Costa Rica to Antarctica.

Should it grow to maturity, the animal could weigh as much as 40 tons and measure as long as 60 feet.

All told, a whale in the Boston Harbor is a rare sight, though not completely unheard of – the last time one was spotted was in 2005.

However, that may change as humpbacks continue to become more populous due to increased regulation.

Legislative action first began in 1946 with the enactment of the International Convention for the Regulation of Whaling, which was directed at stopping the commercial harvesting of the animals. Then, in June of 1970, the humpback was listed as an endangered animal.

In all, NOAA reports an increase in humpbacks in the North Pacific alone from 1,400 in 1966 to an estimated 20,000 today.