MOSS LANDING, Calif. (AP) – Experts are struggling to restore the U.S. West Coast’s southern sea otters to their historic range. The effort reflects global recognition of the crucial role predators play. Fur hunting nearly wiped out southern sea otters. Government protections have brought up their numbers to more than 3,000. But senior research biologist Teri Nicholson at California’s Monterey Bay Aquarium says the otters are stuck. Today they occupy only a quarter of their historic range and haven’t really budged from their 300-mile enclave along central California for 20 years. Without key predators to keep them in check, voracious purple sea urchins have gobbled up more than 90 percent of the kelp forests along Northern California. Commercial divers are hand-picking the urchin from surviving kelp, which provide crucial cover to otters and others.