An international team of scientists says that the critically endangered vaquita, a species of porpoise (Phocoena sinus) found only in Mexico’s Gulf of California, is fast approaching extinction and that all gillnet fishing in the animal’s range must be banned. The team, which was established by the government of Mexico, warns that the number of porpoises has been cut in half since 2012, when about 200 remained. Now, a mere 97 are believed to survive. Of these, 25 are thought to be reproductively mature females.

The vaquitas, whose popular name translates as “little cow,” are dying at an accelerated rate because of an increase in the illegal gillnet fishery for the totoaba (Totoaba macdonaldi). Totoaba, which can grow to more than 1.8 meters and 135 kilograms, are also critically endangered. Their swim bladders are highly prized as a traditional health food in China, and a single bladder can command thousands of dollars. Consequently, a surge in illegal gillnetting has undermined Mexico’s efforts to ban all commercial fishing in a vaquita refuge and to guide fishers toward other careers.

The scientists report that one in five vaquitas are drowning each year in the nets; the population is declining at a rate of 18.5% each year. In a report to the Mexican presidential commission on vaquita conservation, the scientists urge that the country establish a gillnet exclusion zone for the small porpoises’ entire range beginning in September 2014. The commission will be meeting again at the end of August to discuss the possible ban.