An Arizona Illustrated Special - La Vaquita This week on Arizona Illustrated, producer Vanessa Barchfield takes us on a journey to the Sea of Cortez where the most endangered marine mammal on earth is fighting for survival against overwhelming odds. The United Nations says that a million species across the planet are at risk of going extinct, including one-third of the world's marine mammals. The vaquita, a small porpoise that lives in the salty waters of the Upper Gulf of California, is poised to lead the way. Its total population is currently estimated at 12. We see firsthand the efforts being made to save this creature and explore why, despite years of warnings about its fate, the vaquita population continues to decline.