But only high-end sushi joints are worried.

Bluefin is kind of the new ivory tusk; a socially irresponsible luxury item coveted by the super-rich. Although it can show up (often mislabeled) on the menus at your average neighborhood sushi restaurant, most of these mid-market places can easily fill the hole with yellowfin or another more affordable fish if bluefin is banned. And a lot of bluefin's mystique is hype: "Most of us couldn't tell the difference between bluefin and yellowfin, or even another type of fish altogether, especially once its combined with rice," says Safina. His Blue Ocean Institute has partnered with culinary nonprofit Chefs Collaborative to create Green Chefs, Blue Oceans, an online program that teaches chefs how to choose more sustainable seafood for their restaurants.

Want to know what you can sub in for bluefin and other non-sustainable sushi choices? Download the Blue Ocean Institute's sushi guide here.