SACRAMENTO -- Crews were racing Thursday to mop up 58,000 gallons of fuel that spilled after a cargo ship bumped into the San Francisco-Oakland Bay Bridge.
Spread by the tides, the fuel slick from Wednesday's accident shut down several beaches and threatened shorebirds, seals and other marine mammals that make a home in the bay.
By Thursday afternoon, 26 oil-covered birds had been rescued by wildlife crews, while six birds were found dead. Hundreds more had been caught in the spreading slick, said Steve Edinger, assistant chief for the California Department of Fish and Game.
The slick had also spread outside the bay, as far as Tennessee Point in Marin County, 10 miles north of the Golden Gate.
"This is a significant event," Edinger said. "This is one we're very concerned about."
He said the last major oil spill in the bay occurred in 1996, when 10,000 gallons oozed out of a ship in a repair facility.
Melissa Hauck of the U.S. Coast Guard said eight oil-skimming boats were working to clean up the slick. By late afternoon, 9,500 gallons had been collected, as well as 3 cubic yards of oil in gel or solid form. The spill was of bunker fuel, a viscous fuel used on ships that is heavy and can be difficult to clean up.
Authorities also laid 11,000 feet of log booms around the 810-foot container ship Cosco Busan, which was towed to an anchorage off Candlestick Point in San Francisco after it nudged the Bay Bridge in morning fog. No more fuel was leaking from the vessel, Hauck said.
The ship struck a steel and concrete buttress that protects one of the suspension bridge's massive support towers about 8:30 a.m. Wednesday, gouging the hull on the front port side above the water line. Authorities said the bridge piling was not damaged and that the protective shield would be repaired.
Coast Guard officials said the Cosco Busan was being guided out of the bay by a pilot familiar with the waters when the accident occurred.
The spill in the bay is relatively small. The 1989 Exxon Valdez disaster dumped 11 million gallons of crude oil off Prince William Sound. A spill in 2001 off the Galapagos Islands spread more than 160,000 gallons through the ecologically fragile archipelago.
Still, public officials voiced criticism that the Coast Guard initially underestimated it.
Hours after the accident, Coast Guard officials described the fuel leak as a relatively insignificant 140 gallons. But by Thursday morning, the estimate had skyrocketed to nearly 60,000 gallons.
Sen. Barbara Boxer (D-Calif.) released a letter she wrote Thursday to the head of the Coast Guard, expressing dismay over the delay in accurately assessing the risk as well as questioning the investigation into the cause.
"Many questions remain as to why it took an entire day to determine the gravity of this spill, and whether the Coast Guard took appropriate measures to conduct drug and alcohol tests on the ship's pilot and navigators in a timely fashion," Boxer wrote to Adm. Thad W. Allen.
Coast Guard officials said the investigation was ongoing.
The fuel slick soiled at least nine beaches and parks: Muir Beach, Kirby Cove, Rodeo Beach, Black Sand Beach, Baker Beach, Crissy Field, China Beach, Angel Island and Fort Point.
Thirteen state and federal agencies set up a command center at Fort Mason in San Francisco and were meeting to discuss the mop-up.
Oil slicks create problems for shorebirds by coating their feathers, robbing them of their natural ability to stay warm in the chilly bay water.
"It's sort of like a rip in a wetsuit," Edinger said. "They get cold, they beach themselves and they start preening their feathers. They can ingest oil, and that shuts down their digestive system. They lose energy and the ability to take on water and moisture."
Birds that escape the slick can fall prey to a different peril: They can't find food, become debilitated and may die.
Edinger said most birds being treated were surf scoters, but there were reports of gulls and other shorebirds being affected. He said the next two or three days could see the numbers of imperiled birds jump significantly.
Experts from the Oiled Wildlife Care Network, a UC Davis program, have been called in by Fish and Game.