SAN FRANCISCO - An oil spill fouled miles of fragile coastline Thursday, sending environmentalists scrambling to save tarred marine life and leaving local officials questioning the Coast Guard's response to the ship collision that triggered the slick.

About 58,000 gallons of oil spilled from a South Korea-bound container ship when it struck a tower supporting the San Francisco-Oakland Bay Bridge in dense fog Wednesday. The accident did not damage the span, but the vessel's hull was gashed, officials said.

Tides carried a plume of heavy fuel beneath the Golden Gate Bridge and into the Pacific Ocean. By Thursday afternoon, oil had been sighted as far north as Stinson Beach, about 15 miles north of the city, and at least eight beaches in San Francisco and Marin County were closed.

"What we have here are ribbons of oil just going all over the place," Coast Guard Capt. William Uberti, captain of the Port of San Francisco, said after an aerial survey.

A hazy film of oil surrounded Alcatraz Island, and the plume extended well north and south of the Golden Gate Bridge. Birds were spotted alive and coated in oil, and state officials estimated the number of injured birds was in the dozens. At least six were found dead, the Department of Fish and Game said.

The coast north of San Francisco ranges from sandy beaches to barren cliffs to sensitive marshes. Environmentalists fear the impact on shorebirds, fish and marine mammals could be felt for months, even years.

"We're looking at almost everything being affected," said Sejal Choksi of the environmental group San Francisco Baykeeper.

City officials said Coast Guard initially underreported the size of the spill, believed to be the biggest in the bay since 1988. As late as 9 p.m. Wednesday, Coast Guard officials were still saying just 140 gallons had poured into the bay, according to Mayor Gavin Newsom, who said the city would consider legal action against anyone found liable.

"We would have responded differently if we had accurate information from the get-go," such as laying more boom lines to contain the oil, said Newsom spokesman Nathan Ballard.

Sen. Barbara Boxer also criticized the Coast Guard's response in a letter sent Thursday to Commandant Adm. Thad W. Allen, saying she was "very troubled by the Coast Guard's delay in delivering accurate information to the public and the city of San Francisco."

Uberti said Coast Guard personnel knew the full extent of the spill by around 4 p.m. He rejected any suggestion that the crews could have contained the spill more quickly.

Damage to the ship, as well as limited visibility from the fog, contributed to the pace of the assessment, officials said.

About 9,500 gallons of fuel has been recovered, and 18,000 feet of booms were in place by Thursday afternoon, the Coast Guard said. Crews aboard two helicopters surveyed the damage as 11 skimmers sucked up the oil on the bay and ocean. Teams also walked the shoreline assessing and scooping up the oil.

The ship, called Cosco Buson, is owned by Hong Kong's Regal Stone Ltd., which had leased it to South Korea's Hanjin Shipping for the voyage.

"I'd like to express our concern and regret that this incident occurred and assure the community and the public in the San Francisco Bay area that we're making every effort and (using) every resource available," said Barry McFarley, whose O'Brien Group was hired by the ship's owner to handle its response to the spill.

Authorities were still investigating the cause of the collision.

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Associated Press writers Terence Chea and Paul Elias in San Francisco and Don Thompson in Sacramento contributed to this report.