SAN FRANCISCO, Calif. (KRON) – The largest animals on Earth have gathered 30 miles offshore from San Francisco in potentially record-breaking numbers this week.

Endangered blue whales are feeding on abundant krill in the Greater Farallones National Marine Sanctuary. Researchers recorded seeing 47 blue whales a short distance from the Farallon Islands on Saturday, and NOAA marine animal experts are describing this season for blues as “exceptional.”

“It’s been an excellent year for upwelling, for ocean productivity. But to have 47 blues feeding in one area, each can eat up to 6-tons of tiny shrimp-like krill per day, probably sets a record. The scientists on the island could not see their entire feeding group, so 47 is a conservative number,” NOAA Greater Farallones spokeswoman Mary Jane Schramm said.

Despite their huge size, blue whales can be elusive and hard to find while they are swimming hundreds of miles across open oceans. Seeing so many of these gentle giants together at the same time is exciting for researchers and good news for conservationists.