In 1972 Congress passed the Marine Mammal Protection Act (MMPA), one of the first laws developed to protect a separate category of wildlife, and makes it illegal for any person under legal jurisdiction of the United States to kill, hunt, injure or harass all species of marine mammals, regardless of their population. The MMPA also makes it illegal to import marine mammals or products made from them into the United States. Marine mammals protected under this Act include: dolphins, whales, seals, sea lions, sea otters, polar bears, manatees, dugongs and walruses.
Some exceptions to the MMPA allow certain numbers of marine mammals to be collected for scientific and public display purposes, to be hunted for subsistence use by natives of the North Pacific and Arctic coasts, and to be caught incidental to commercial fishing operations.
Responsibilities for the MMPA is shared by two federal agencies. The National Marine Fisheries Service of the Commerce Department protects all members of Cetacea -- whales, dolphins and porpoises -- and all members of Pinnipedia -- seals -- except walruses. The U.S. Fish and Wildlife Service protects all other species of marine mammals -- walruses, sea otters, polar bears, manatees and dugongs.