A group of four humpback whales were spotted swimming in the San Francisco Bay in a rare occurrence. Marine biologists believe the whales were attracted by a large swarm of anchovies in the area. Screen capture/KGO

SAN FRANCISCO, May 13 (UPI) -- Visitors to San Francisco's Golden Gate Bridge were met with a rare sight on Thursday as a group of humpback whales were seen swimming in the nearby San Francisco Bay.

As many as four whales were seen in the bay according to KGO, as marine biologists suspect the sea mammals were attracted by a large number of anchovies swimming in the area.


"I've been in this game for a lot of decades, and this is the first time I've heard of this many humpbacks coming in this far," Greater Farallones National Marine Sanctuary spokeswoman Mary Jane Schramm told the San Francisco Gate.

Schramm added that its normal for whales to wander into the bay to hunt pray such as the horde of anchovies, but expressed concerns for the humpbacks who are more accustomed to feeding further offshore.

"If they head any direction except west they could get into big trouble," she said. "The deeper they get into the bay, the more acoustically confusing it becomes."

The whales could also pose a threat to passing boaters and other water travelers, as a kite surfer was seen traveling within feet of one pair of whales.

Schramm urged boaters and others to steer clear of the whales while they make their rare visit to the bay.

"If you are in a small boat and a humpback breaches near you, you could be swamped or it could land on you," she said, "It's dangerous, so for your own safety and to prevent wildlife disturbance, don't approach them."