The Office of the U.S. Trade Representative formally requested environmental consultations with Mexico relating to the prevention of illegal fishing, protection of the critically endangered vaquita porpoise in the Gulf of California, and the trafficking of totoaba fish. The request is the first step under the enforcement and dispute mechanism of the U.S.-Mexico-Canada Agreement (USMCA), which could precipitate trade sanctions against Mexico should the country persist in failing to enforce its environmental laws or prevent illegal fishing, as required by multilateral trade agreement obligations. Experts estimate that the entire population of vaquita porpoises has dwindled to just ten, placing the most-endangered marine mammal in precarious danger of extinction. Vaquita become entangled and die in fishing gear set to catch shrimp and finfish, particularly totoaba, a large fish in demand in China for its swim bladder. This request is the first time the U.S. government has invoked the USMCA’s environmental consultation provision since the trade agreement took effect in 2020.