The primary objectives of the Marine Mammal Protection Act (MMPA) are to:

• Prevent marine mammal species and stocks from diminishing to the point that they are no longer a significant functioning part of their ecosystems.
• Restore diminished species and stocks to their optimum sustainable populations.

The U.S. Department of Commerce, through NOAA Fisheries, is charged with protecting whales, dolphins, porpoises, seals, and sea lions. Walrus, manatees, sea otters, and polar bears are protected by the U.S. Department of the Interior through the U.S. Fish and Wildlife Service. The Animal and Plant Health Inspection Service, a part of the U.S. Department of Agriculture, is responsible for regulating marine mammals in zoos and aquariums under the Animal Welfare Act.

The MMPA prohibits the taking and importation of marine mammals and marine mammal products, where “take” means to harass, feed, hunt, capture, or kill any marine mammal, or to attempt to do so. However, exceptions to that prohibition may be made for:

• Pre-MMPA specimens taken before December 21, 1972.
• International agreements entered into by the United States before December 21, 1972.
• Alaska native subsistence harvesting. 
• Scientific research, public display, enhancing the survival or recovery of a species, and incidental take in commercial fisheries.
• Waivers granted by the U.S. government.