( CNN ) -- Humans have driven to extinction four marine mammal species in modern times : StellerÂ´s sea cow in 1768 , the Caribbean monk seal in 1952 , the Japanese sea lion in 1970 and the baiji or Chinese river dolphin in 2006 . As you read this , we are on the brink of losing the fifth . The vaquita ( Spanish for `` little cow '' ) , a small porpoise that lives only in the uppermost Gulf of California , Mexico , is the most endangered of the 128 marine mammals alive today . The vaquita , which some say looks endearing with its unique facial markings , is the smallest of all whales , dolphins and porpoises . The only way to prevent its extinction is if the Mexican , U.S. and Chinese governments take immediate and coordinated action . New evidence presented by a team of international scientists , established by the government of Mexico , shows that the vaquita is running out of time even faster than we thought . â€ŽThe population is very small and disappearing rapidly , with more than half lost in just the last three years . There were about 200 vaquitas a few years ago , and now a report presented recently to the Mexican government by an international recovery team estimated that fewer than 100 remain . Each year , about one in five vaquitas is drowned in fishing nets , both legal and illegal . This makes it likely that at least another 20 % of the population will be lost during the next fishing season , shrinking the total number even more . In light of this alarming decline , the international team has called for an emergency regulation establishing a gillnet exclusion zone for the entire range of the vaquita starting in September . The vaquita 's fate has also long been tied to the totoaba , a large fish that lives in the upper Gulf of California as well . Entanglement in gillnets set for totoaba was the primary cause that brought the vaquita to low levels by the mid-1970s . Totoaba were overfished by the mid-1970s , and the species was listed as endangered by Mexico in 1975 , and by the United States in 1979 . Massive illegal fishing of the totoaba has resurged in the past three years because its swim bladder is used as a very expensive traditional health food in China , especially in Guangdong and Hong Kong . Dealers along the isolated beaches of San Felipe and El Golfo de Santa Clara , two small fishing towns close to the U.S. border , buy swim bladders from fishermen by paying several thousand dollars per kilogram . Thousands of swim bladders are likely then smuggled across the border to the United States and shipped to China -- where a kilogram can be reportedly worth much more on the black market -- leaving thousands of dead totoabas and tens of drowned vaquitas to rot . Mexican authorities have acted to prevent the extinction of the vaquita . Over the past five years , the Mexican government , together with national and international foundations , has allocated more than $ 30 million to save this porpoise and support the livelihoods of the local fishing communities . Most of this money has been used to compensate the fishermen affected by the creation of a vaquita refuge in 2009 and to assist those wanting to switch to safer fishing techniques . In February 2013 , the Mexican government established a committee to advise President Enrique Pena Nieto on urgent measures to save the vaquita , led by Mexico 's secretary of the environment . Four months later , in a bold move , the government mandated the elimination of all shrimp gillnets -- in which vaquitas are caught -- through their gradual replacement with a newly developed safer net within three years . But more needs to be done . Despite these measures , the vaquita will be lost unless the illegal totoaba fishing is stopped immediately . It is now or never , and only high-level action can save this critically endangered porpoise . We urge Pena Nieto to stop the illegal fishing of totoaba by even stronger enforcement of the gillnet ban and to extend the refuge boundaries to cover the entire vaquita habitat . This means eliminating all gillnet fisheries within the expanded refuge and compensating the fishermen , while allowing for a transition toward new gear that catches shrimp but not vaquitas . We also urge U.S. President Barack Obama to take swift and decisive action through the newly created White House Wildlife Trafficking Group . The first immediate step is to scale up the already significant law enforcement efforts on transborder shipments of totoaba products . Finally , we urge China Premier Li Keqiang to immediately stop the illegal entrance of totoaba products . It is still possible to save the vaquita , but this is clearly the last chance . We call upon the governments of the United States , China and Mexico to take swift action to save this unique and beautiful species for present and future generations .
The vaquita , a small porpoise that lives in Gulf of California , Mexico , is near extinction . Robert L. Brownell Jr. , Zhou Kaiya and Zhou Kaiya : Fewer than 100 vaquitas remain . They say Chinese , U.S. and Mexican governments must take swift and coordinated action . Fewer than 100 way is if Mexico stops the illegal fishing of totoaba , which often ensnares vaquitas .