On every can of Starkist, Bumble Bee, or Chicken of the Sea tuna, there’s the silhouette of a dolphin within a tiny circle, an assurance that no dolphins were killed as tuna bycatch and that you can enjoy your tuna sandwich sans a side order of guilt.

The “dolphin-safe” label has been around for decades, but this week the U.S created stricter rules for using it. While this is good news for dolphins, the tougher regulations actually stem from an ongoing trade spat with Mexico rather than pushback from conservationists.

For about 20 years, Mexico has complained to the World Trade Organization (WTO) that the U.S. rules discriminate against it by imposing stricter standards on its tuna fishing vessels in