Delegates to the CITES meeting heard evidence that the trade in the swim bladders of a Mexican fish called the totoaba is endangering one of the rarest marine mammals in the world. Vaquitas – porpoises that are also the world’s smallest cetaceans – are only found in the northernmost section of the Gulf of California off the west coast of Mexico.

They are caught as bycatch in gillnets intended for the totoaba, and current estimates put their population at under 100. The swim bladders are exported mainly to China, where they are believed to possess an unproven medicinal quality. Campaigners say China is not doing enough to stop the trade, which is illegal under CITES.