Many have been hunted to near extinction. Some have recovered, such as the sea otter and the gray whale. The mechanized era , characterized by the development of the explosive harpoon in 1868 and the steam engine, resulting in motorized ships. The factory ship era , enabling processing of the whales at sea. In 1946 the International Whaling Commission was established to protect the industry.
Political pressure is the biggest enforcing power.
Populations are said to be depleted if the number is below this level. They breed near the equator during winter. Gray whales stir up bottom sediments and feed on benthic crustaceans. This is important for feeding and breeding. The gray whale has the longest migration of any animal.