Apparently there were smaller amounts in cans of Bumble Bee, Chicken of the Sea, and Starkist, and a Riverside County Superior Court judge ordered the three companies to pay $3.3 million in penalties. Restitution to consumers was considered impractical so the companies agreed to donate $300,000 worth of canned tuna to California food banks within the next four months. From KPCC:
Consumer complaints initiated a yearlong investigation in 2010 by the California Department of Food and Agriculture that found the tuna retailers had violated federal regulations that set a certain "standard of identity" for canned tuna. It's basically a balance between how much liquid and tuna is in a can based on how big that can is. The Riverside County District Attorney's Office joined the San Diego and Marin County DAs' offices in filing a civil action.
From AP:
In a statement from the National Fisheries Institute, the seafood trade organization that represents the three companies said the dispute centers on the Federal Department of Agriculture's 55-year-old pressed weight standard. "Rather than litigate against an outdated standard, the companies will continue their own efforts with FDA towards establishing a more modern, consistent and reliable standard of measurement that can be easily understood and verified by consumers," the trade association said. "While working with FDA to change the standard, the brands continue to comply with FDA pressed weight regulations."