Four more whales were found dead in San Francisco Bay over the weekend, bringing the total to four this year. The first death was reported on March 17, with officials stating it was likely caused by a vessel. Experts from The Marine Mammal Center and the California Academy of Sciences have relocated at least one of the whales and are taking blubber samples for a necropsy. This comes amid growing concern for the species, which has seen its population decrease by over 50% since 2000.