Bumble Bee Foods is a survivor. Founded in 1899, Bumble Bee, which is headquartered in San Diego, owns two of the last three canned tuna factories in the U.S. (in southern California and Puerto Rico) and one of the last two canned clams plants (in Cape May, N.J.). The company went bankrupt in the late 1990s but it has emerged stronger, and it's now North America's largest branded shelf-stable seafood company.

But Bumble Bee's tuna business, which accounts for more than half of its revenues of close to $1 billion, has a new worry: If the world's fisherman can't agree to intelligently manage capacity, tuna stocks could well be threatened.

"We're at maximum sustainable yield," says Chris Lischewski, Bumble Bee's president and CEO.

Bumble Bee itself doesn't own fishing boats -- it's a processor and marketer of seafood -- but its future obviously depends on a reliable supply of fish.

I met Chris a week ago at FORTUNE's Brainstorm Green conference, where I led a panel on sustainable seafood. (Tomorrow, I'll blog about Josh Goldman of Australis, who also spoke.) A former management consultant who has run Bumble Bee since 1999, Chris told me that he didn't worry much about fish supplies until the mid-2000s when it became apparent to him that global efforts to regulate tuna fishing weren't working.

In response, Bumble Bee with the World Wildlife Fund and industry rivals, including Starkist (a unit of Korean fishing conglomerate Dongwon) and Chicken of the Sea (now owned by a Thai parent), created the nonprofit International Seafood Sustainability Foundation (ISSF) in 2009. Chris now chairs its board, and he has had to become an expert in fisheries management.

He told me that responsible operators in the seafood industry and mainstream environmentalists share a common goal, for the most part: They want to preserve the world's wild fish. That doesn't mean they always agree, of course. Greenpeace Canada, for example, spanked Clover Leaf, a unit of Bumble Bee, in its recent seafood rankings. Chris says that's partly because Clover Leaf didn't respond to a Greenpeace questionnaire.

His bigger concern is that tuna fishery regulation is ineffective. Partly that's because tuna are tough to regulate: They never stop moving, they are widely but sparsely distributed around the world and they can travel thousands of miles, onto the high seas, beyond the reach of any nation. Tuna fishing is regulated by regional fisheries management organizations, or RFMOs, made up of many countries (19 in one central Pacific group), some of which control fishing grounds, others that own the boats. Policing the high seas is a big challenge, Chris told me. "There's absolutely nothing that stops new boats from coming in," he said.