SAN FRANCISCO—A pod of blue whales were sighted in San Francisco Bay on June 13, with consistent sightings throughout the past few weeks. As a result of these common sightings, the U.S. Coast Guard issued a warning to boaters to remain on the look out, and to maintain distance and slow speeds to avoid harming the whales.

The whales are slowly moving through the bay in large numbers in search of food. On June 13, biologists from Point Blue Conservation Science sighted at least 47 blue whales from the Farallon Islands in a one-hour period, and about 23 blue whales a few days prior.

Blue whales are listed as endangered under the Endangered Species Act. The primary threats currently facing the blue whale population are vessel strikes and strangulation from fishing gear. They are the largest animal on the planet, and when focused on feeding, they are not likely to notice or avoid a nearby ship. It is not uncommon for ships to accidentally hit them, if they are out of sight behind or beneath a ship. 

Recreation boaters in San Francisco and the local fishing industry have been advised to proceed with caution through the water, and are also encouraged to report a dead, injured or stranded marine mammal to the West Coast Marine Mammal Stranding Network at 1-866-767-6114.