With four trained U.S. Navy dolphins acting like herding dogs and an array of special nets, enclosures, and stretchers, conservationists today began their roundup of the vaquita, a porpoise that lives in the upper Gulf of California. Only an estimated 30 vaquitas are left in the wild, and those numbers have been dwindling despite efforts by the Mexican government to ban fishing with gillnets, which inadvertently trap and drown these marine mammals. So as a final, desperate measure, the International Committee for the Recovery of the Vaquita and the Mexican government brought a team of experts to San Felipe, Baja California to try to locate at least some of the vaquitas and corral them in nets. They hope to transfer 10 to 12 of these rare survivors to a temporary sanctuary—a sea pen off San Felipe—and eventually to release them in a part of the gulf that’s been cleared of gillnets and illegal fishing activity. The rescue effort, Vaquita CPR, will last two weeks, program spokesperson Steve Walker says. The strategy—first proposed by biologists last year—is a risky endeavor because porpoises, unlike dolphins, tend to be very sensitive and are hard to keep in captivity. But recent successes, including the captive breeding of harbor porpoises rehabilitated after being tangled in nets or stranded, gives the team hope of reviving the species.