Here’s why humpback whales have been swimming in Boston Harbor lately

Humpback whales are swimming in Boston Harbor for an important reason, according to experts.

“The whales are following their food,” said Allison Ferreira, a spokeswoman for the National Oceanic and Atmospheric Administration. “They’re chasing food sources,” which sometimes brings them close to shore.

Such was the case Tuesday, when state Department of Conservation and Recreation officials shared a video of a humpback whale that was seen leaping from the water near the Deer Island wastewater treatment plant.

Humpback whales feed on menhaden, also known as bunker or pogies, and experts say that kind of fish is what likely drew the young whale into the inner harbor.

Although humpback whale sightings in Boston Harbor are uncommon, they do happen occasionally. The juvenile whale in the video has been spotted several times in the inner harbor since Sunday. Prior to that, a group of five to six humpback whales was seen in the outer harbor on Aug. 24 and 25, according to Laura Howes, director of research and education for Boston Harbor Cruises.

Howes said the whales that venture into Boston Harbor are typically juveniles who are looking to feed.

“Sometimes younger animals try different things,” she said.

Howes said the humpback whale measures between 25 and 30 feet, and it’s been spotted several times in the harbor since Sunday, including as recently as Wednesday morning.

“We’ve been seeing this on and off as recently as this morning,” she said. “I’m guessing it may continue. It appears pretty healthy. As far as we can tell, there’s nothing wrong it.”

The video of the whale breaching the water has been viewed thousands of times on social media.

“It’s exciting,” said Susan Kane, the islands district manager for the state Department Conservation and Recreation. “I know it’s not unheard of, but what’s different this time, they seem to be enjoying being here. There are these massive schools of pogies all over the place. [The whales] seem to be very healthy, and playful even.”

Kane said it was fitting that the Deer Island wastewater treatment plant was clearly visible in the video. After all, it wasn’t that long ago that the harbor was known as the dirtiest harbor in America. The presence of whales and other marine life shows just how far the harbor has come.

“We see it, on a day to day basis, just how much cleaner the harbor is,” Kane said.

But there is concern about the whale’s safety.

“It’s not a safe place to be. It’s an extremely busy harbor,” Howes said. “It could easily be hit. We’re hoping it will go away, for its own safety.”

Vessel strikes are one of the biggest threats to humpback whales, according to NOAA. They are also susceptible to getting tangled up in fishing gear and being harassed by vessels.

Ferreira said it’s important that mariners keep an eye out for whales and leave them alone. (For a complete list of NOAA’s whale watching guidelines, click here.)

“Be aware that they’re in the area, and proceed with caution,” Ferreira said. “We do encourage people, stay at least 100 feet away. Don’t chase down the animals. It’s illegal to chase down these animals or interfere with their activities in any way. Just let them be.”

A juvenile humpback whale was seen breaching off of Spectacle Island earlier today 🐋 a beautiful and rare sight to see, captured by @MassDCR while doing routine Boston Harbor Island rounds #conservation #wildlife pic.twitter.com/iqp1Bdak50

— MassDCR (@MassDCR) August 28, 2018