SANTA MONICA, Calif. — It is sport among black belt sushi eaters here to see just how daring one’s palate can be. But even among the squid-chomping, roe-eating and uni-nibbling fans, whale is almost unheard of on the plate. It also happens to be illegal.

Yet with video cameras and tiny microphones, the team behind Sunday’s Oscar-winning documentary film “The Cove” orchestrated a Hollywood-meets-Greenpeace-style covert operation to ferret out what the authorities say is illegal whale meat at one of this town’s most highly regarded sushi destinations.

Their work, undertaken in large part here last week as the filmmakers gathered for the Academy Awards ceremony, was coordinated with law enforcement officials, who said Monday that they were likely to bring charges against the restaurant, the Hump, for violating federal laws against selling marine mammals.

“We’re moving forward rapidly,” said Thom Mrozek, a spokesman for the United States attorney for the Central District of California. Mr. Mrozek declined to say what charges could be brought against the restaurant, but said they could come as early as this week.