Leonardo DiCaprio took to Twitter to shed light on an issue not many know about: the plight of the Mexican porposie, or vaquita, as it is also known.

DiCaprio tweeted on May 11 that “the vaquita is the most endangered marine mammal in the world” and urged his 17.5 million followers to “take action.”

Additionally, DiCaprio went on Instagram to express those same thoughts.

“The smallest member of the porpoise family is the most endangered marine mammal in the world. Unsustainable and illegal fishing practices have caused a dramatic decline in the vaquita’s population. Fewer than 30 vaquita may be left in the wild and without immediate action, they face imminent extinction. Join me and @World_Wildlife and let President Peña Nieto of Mexico know that we demand action to protect the vaquita today,” he wrote in a separate Instagram post showing a picture of a vaquita.

The tweet got the attention of Pena Nieto. He responded to DiCaprio the next day.

“I welcome @LeoDiCaprio and @World_Wildlife’s concern regarding the Vaquita Marina,” President Nieto wrote in his first series of tweets about the issue. “@Mexico has focused all its efforts to prevent the extinction of this species.”

There may be fewer than 30 vaquita left in the Upper Gulf of California, the only place on Earth where the tiny porpoise live, according to the World Wildlife Fund.

Illegal fishing and lax enforcement of existing fishing laws have contributed to the rapid decline of the vaquita, according a recent report by the International Committee for the Recovery of the Vaquita.

President Pena Nieto said his administration is making an effort that should have started a lot sooner. He pointed out the two-year ban on gill nets in the area, as well as the presence of a Mexican Navy patrol policing illegal fishing.

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