The mission of the Marine Mammal Center in San Francisco is to " expand knowledge about marine mammals their health and that of their ocean environment and to inspire their global conservation." The center rescues injured and sick animals and helps rehabilitate them so they can return to their natural habitat. During the rehabilitation process, the center also studies the animals so they can better understand the lifestyle and health of the creatures. Some of the animals they treat suffer from malnourishment, separation, and disease. Nearly 10% of the animals treated have been injured by human interaction including entanglement, illegal pick-ups, gun shots, and boat strikes. The center works with a variety of animal scientists to put together treatment and released programs that will best benefit each animal. All cases are documented so the rescue information can be used in future situations. The facility has been in operation since 1975 and has treated more than 16,000 animals including sea lions, elephant seals, whales, harbor seals, sea otters, fur seals, dolphins, harbor porpoises, and others. The center is staffed by both volunteers and staff doctors and experts. The research programs combine veterinary clinics, rehabilitation specialists, pathologists, wildlife biologists, and research scientists.