If your Thanksgiving dinner traditionally includes fresh Dungeness crab, you can just about forget tradition this year. In the wake of the Cosco Busan fuel spill in San Francisco Bay, Gov. Schwarzenegger closed commercial and sportfishing seasons in the potentially affected area until Dec. 1. That zone includes all of San Francisco Bay west of Carquinez Bridge and three miles off the Golden Gate from Point Reyes Lighthouse south to San Pedro Point just north of Half Moon Bay.

San Francisco's crab season, customarily just under way, is on hold until late next week as state authorities collect and analyze marine samples for chemical contamination. Almost 1,000 crabs, mussels, herring and Shiner surfperch have been gathered in the bay and along the coast and are being tested for the presence of polycyclic aromatic hydrocarbons, says Sam Delson, spokesman for the Office of Environmental Health Hazard Assessment, the science arm of the California Environmental Protection Agency. Results are expected next Wednesday.

"We plan to complete our evaluation within a day or two of receiving the results and hope to make an announcement before the end of the month," Delson says.

At the request of commercial crab fishers, the agency will collect additional samples this weekend from beyond the three-mile limit of the defined spill zone, he adds.

In the meantime, a San Francisco Chronicle article today reported that nearly 100,000 pounds of live Dungeness crab caught by Oregon fishermen near the Farallones had been offloaded in Monterey. The crabs reportedly were bound for sale in San Francisco, though buyers contacted by the paper said they weren't buying any.

Unless consumers know for sure that the crab they plan to serve tomorrow is from the unaffected waters of the Pacific Northwest, they should exercise caution, indicates Delson. "It's better to be safe than sorry," he says. "It's best to err on the side of caution until we can remove all doubt."