With endangered whales congregating in the food-rich waters around the Farallon Islands, the U.S. Coast Guard is asking large ships to slow down in hopes of avoiding fatal collisions with the huge cetaceans.
The Coast Guard's message, broadcast over marine band radio, asks heavy vessels — including tankers, container and cruise ships — to approach and exit San Francisco Bay at no more than 10 knots, about half their normal speed.
The slowdown is intended to reduce ship strikes on endangered blue and humpback whales, said Dan Howard, superintendent of the Cordell Bank National Marine Sanctuary, which covers 529 square miles off the Sonoma and Marin county coast.
Shipping lanes carry about 20 heavy vessels a day in and out of the bay cross the Cordell Bank and adjacent Farallon Islands marine sanctuaries, managed by the National Oceanic and Atmospheric Administration.
NOAA requested the slowdown message after biologists stationed on Southeast Farallon Island 30 miles outside the Golden Gate counted a remarkable concentration of whales in late June.
"There is food everywhere," Howard said, referring to an abundance of krill, a tiny shrimp-like crustacean that forms the cornerstone of the marine food chain.
Blue whales, the largest animals on the planet, feed almost entirely on half-inch-long krill that live in massive swarms.
The leviathans are of concern to scientists because their northeast Pacific population of about 2,000 has not rebounded in the 43 years since commercial whaling was ended in the United States.
During a one-hour break in the fog on June 27, the Farallon Island biologists counted 33 humpback whales, six blues and one fin whale, Howard said.
The following day, they spotted 25 humpbacks, seven blue whales, one fin and one gray whale.