Vaquita, the world's rarest marine mammal, is on the edge of extinction. The plight of cetaceans—whales, dolphins, and porpoises—as a whole is exemplified by the rapid decline of the vaquita in Mexico, with about 10 individuals remaining. This little porpoise wasn't discovered until 1958 and a little over half a century later, we are on the brink of losing them forever. Vaquita are often caught and drowned in gillnets used by illegal fishing operations in marine protected areas within Mexico's Gulf of California. The population has dropped drastically in the last few years. 

more- https://www.worldwildlife.org/species/vaquita