The two samples from Sushi Katsu-ya in Studio City came back with mercury concentrations of 1 part per million and higher, above the FDA's threshold for mercury in any seafood species, [Eli Saddler] said. One sample from Sushi Nozawa, also in Studio City, came back just shy of the limit, Saddler said.

Saddler said the yellowfin samples culled from the Southern California restaurants had a median mercury concentration of 0.82 ppm, not far from the FDA limit. The testing methodology used by CRG is similar to what the FDA uses, said Richard Gossett, CRG's laboratory manager.

POPULAR FOOD: Tuna is prepared for customers at Sushi Sasabune in West Los Angeles. "We would like to be able to get fish that has been tested for mercury," owner [Nobi Kusuhara] said.; PHOTOGRAPHER: Photographs by Anne Cusack Los Angeles Times; DISCLOSURE: Nobi Kusuhara says knowing the mercury content in fish would be good for his customers and his restaurant.; PHOTOGRAPHER: Anne Cusack Los Angeles Times; ON THE ALERT: Nobi Kusuhara, owner of Sushi Sasabune in West L.A., warns pregnant customers not to eat swordfish or tuna.; PHOTOGRAPHER: Photographs by Anne Cusack Los Angeles Times; RAW APPEAL: Albacore tuna, left, and salmon, both popular sushi items, are prepared at Sushi Sasabune.; PHOTOGRAPHER: Anne Cusack Los Angeles Times