A preliminary Coast Guard investigation has determined that human error caused a cargo ship to crash into the San Francisco-Oakland Bay Bridge.
On Saturday, crews intensified efforts to rescue wildlife and clean up the resulting oil spill.
"There were skilled enough individuals on board this ship," said Rear Adm. Craig Bone, the Coast Guard's top official in California. "They didn't carry out their missions correctly."
Coast Guard officials declined to lay blame on any specific individual or provide further details on the mistakes that were made Wednesday morning aboard the 926-foot ship Cosco Busan.
Investigators were focusing on issues surrounding the ship's official protocol for safely navigating out of San Francisco Bay, including possible communication problems between the crew, the pilot guiding the ship and Vessel Traffic Service, the Coast Guard station that monitors the bay's shipping traffic.
Coast Guard Cmdr. Andrew Wood said "the mere fact that [the ship] collided with a fixed object" offered clear evidence that a communication problem had occurred.
But a language barrier between the pilot, Capt. John Cota, and the ship's all-Chinese crew probably was not a factor in the crash, since the captain and officers are required to speak English, officials said.
Cota, who is American, is among a group of specially trained pilots who are not members of a ship's crew but typically come on board to maneuver cargo vessels in San Francisco Bay.
Bone declined to comment on a report that the Coast Guard had warned the pilot about the ship's course shortly before the accident about 8:30 a.m.
John Meadows, the lawyer for the ship's pilot, told the San Francisco Chronicle that the Coast Guard's nearby traffic facility radioed Cota and questioned his bearings.
The pilot immediately responded by saying the ship's instruments showed he was on the correct heading, Meadows told the newspaper.
Bone acknowledged that there were communications between the ship and the Coast Guard's traffic facility before the crash. He said the communications involved the ship's course and speed, but he declined to comment further on the nature of the exchange.
The Cosco Busan was headed out of the bay when it sideswiped a support on the San Francisco-Oakland Bay Bridge, leaving a gash nearly 100 feet long on the side of the ship.
The crash ruptured two fuel tanks, which leaked about 58,000 gallons of heavy bunker fuel -- the bay's worst oil spill in nearly two decades.
On Saturday, the Coast Guard increased the number of ships skimming oil from the bay to 20 from 11 the previous day, said Petty Officer Sherri Eng.
Nearly 20,000 gallons of oily liquid had been sucked up by Saturday morning, according to the Coast Guard.
About 770 workers joined cleanup crews on the water and along beaches to mop up the damage -- a job that is expected to last weeks or possibly months.
Rescue teams also raced to save hundreds of seabirds tarred with black shipping fuel. At least 60 birds were found dead while 200 live birds were recovered and sent to a rehabilitation center in Solano County.
State wildlife officials said they have received hundreds of reports of oiled birds found on Bay Area beaches, two dozen of which were closed after tides carried the oil under the Golden Gate Bridge and out to the Pacific Ocean.
About 65 Bay Area fishermen met Saturday and voted to ask Gov. Arnold Schwarzenegger to close the commercial and sport crabbing season.
The crabbers want the governor to close crab fishing along the California coast from Point Arena on the north to the Mexican border until the waters are deemed safe, said Larry Collins, vice president of the Crab Boat Owners Assn.
"We want the season closed until the oil is out of the water and no one gets sick from eating crab that's been contaminated by the oil," he said.
The sports season started Nov. 3 and the commercial season is slated to start Thursday.
The crabbers said the oil spill does not harm the crustaceans in their habitat on the ocean floor. The oil harms crabs when they are transferred to the live tanks in which they are housed after being caught.
Collins said crabs brought in by some fishermen Saturday were dead on arrival.
Authorities said most of the spilled oil will never be recovered, and eventually will dissolve into the water. Concentrated globules could remain for months and cause problems for seabirds.
Most of the injured birds are surf scoters, a duck-like species that lives on the water's surface and dives for fish. When oil gets on their feathers, it disrupts their waterproofing system and ability to stay warm, forcing them on shore, where they are at risk of starvation.
Officials from the state Department of Fish and Game said that the fuel generally stays on the water's surface, and that they had not seen any evidence of fish being harmed -- though they are concerned that the spill could affect bay herring that spawn at this time of year.
Schwarzenegger declared a state of emergency Friday after meeting with local, state and federal officials overseeing the cleanup. The proclamation makes additional state personnel, funding and equipment available.