After they had played Lightnin' Hopkins and the Reverend Gary Davis, and after they had delighted the crowd with their signature "Hesitation Blues," acoustic blues throwbacks Hot Tuna captured the spirit of the San Francisco Blues Festival with their final number of their Saturday afternoon set.

New member mandolinist Barry Mitterhoff bantered with bandmate Jorma Kaukonen. "You and Jack (Casady) have played in San Francisco before," he said.

"What tipped you off?" countered Jorma.

"Well, they seem to know you," said Mitterhoff to a roar from the crowd, at least a part of which undoubtedly had seen Kaukonen and Casady during the heydey of The Jefferson Airplane in San Francisco in the 1960s. To supplement their psychedelic personae, Kaukonen and Casady had begun performing as Hot Tuna in 1969, first as a full combo and later as a duo playing straight-ahead acoustic blues featuring Jorma's fingerpick-style guitar.

Despite that history, this was Hot Tuna's very first appearance at the 36-year-old festival. And now Jorma was introducing their final song, written by another important bluesman, "The San Francisco Bay Blues."

"I got the blues from my baby down by the San Francisco Bay...." The audience, basking in the September sun on the Great Meadow at Fort Mason, with the Golden Gate Bridge and bobbing sailboats in view at stage right, ate it up. "If I ever come back to stay, it'll be another brand new day, walking with my baby down by the San Francsico Bay."

After the set, Kaukonen and Casady chatted with festival producer Tom Mazzolini about their Bay Area roots, though Casady acknowledged they are just tourists when they come to town now. Nevermind, though. Hot Tuna is part of this city's cultural DNA.

The Hot Tuna performance was one highlight of the first day of the venerable festival, taking advantage of the glorious September weather overlooking the Bay at Fort Mason's Great Meadow. The other highlight came two hours later, when another legend from a seminal '60s rock band closed out an entertaining all-star blues revue featuring a cavalcade of electric blues performers. After all that great music, Elvin Bishop reminded fans of the fun and excitement that a high-powered blues rock can deliver.

Bishop was a key member of the Paul Butterfield Blues Band who went on to a successful solo career in the 1970s and '80s. With his rubber face, rock star poses, frenetic stage antics, and raunchy slide guitar, he immediately got the crowd going with two of his hits, "Little Brown Bird" and "My Dog." On the latter, he actually brought his dog on stage with him.

Then he brought back some of the other members of the revue cast, including old-time blues crooner Finis Tasby, harmonica/vocalist John Nemeth, and the wild backup band The Mannish Boys, for a closing few numbers. The day finished with a fine rendition of "The Nighttime is the Right Time," a track from Bishop's comeback album "The Blues Rolls On," just out with a true all-star set of guests including B.B. King, Warren Haynes, Derek Trucks, George Thorogood, James Cotton and more.

Earlier in the day, fans had enjoyed a range of blues styles from the second-generation bluesman Elmore James, Jr., Texas folk-blues shouter Ruthie Foster, powerhouse guitarist Michael Burkes, and Gulf Coast soul throwback Barbara Lynn.

It made for a powerful day of music and a very satisfying festival experience. And a second day full day of blues with headliners Buckwheat Zydeco and Johnny Winter remained on tap for Sunday. While bigger and newer festivals like next week's Hardly Strictly Bluegrass and the recent Outside Lands may grab more attention these days, this well-run and musically honest festival deserves to be listed among the city's best music events of the year.