Turtles 'face extinction' without marine protection This would be particularly useful in so-called "convergence zones" where opposing currents pushing together create vast fields of plankton and attract the rest of the food chain, making the waters especially crowded. One of the largest examples, the North Pacific Convergence Zone, moves 1,000 km from north to south seasonally, crossing waters used by Hawaiian fishermen. The zone is also used as an "interstate highway" for loggerhead turtles, a critically endangered species, as they migrate, researchers said at the American Association for the Advancement of Science (AAAS) annual meeting in Vancouver. Larry Crowder, professor of marine biology at Stanford University, said: "The North Pacific Convergence Zone is always there, but it moves. We usually think of protected areas as being in a place, and we think of that place as being locked down to a map. But places in oceans aren't locked down to a map, they move. Making conservation areas mobile would also account for non-annual ocean trends, like El Nino, and the effects of climate change which are causing species to move from their traditional habitats, he added.