Claims that the seacoast was populated about 30,000 years ago have been largely discredited (see below); present population density is very low. The sea contains significant resources of petroleum and natural gas under its shelf, such as the Amauligak field. They were discovered in the period between the 1950s and 1980s, and since the latter part of that period their exploration has become the major human activity in the area. The traditional occupations of fishery and whale and seal hunting are practiced only locally, and have no commercial significance. As a result, the sea hosts one of the largest colonies of beluga whales, and there is no sign of overfishing. To prevent overfishing in its waters, the US adopted precautionary commercial fisheries management plan in August 2009. In April 2011 the Canadian government signed a memorandum of understanding with the Inuvialuit as a first step in developing a larger ocean management plan. The Canadian government announced in October 2014 that no new commercial fisheries in the Beaufort Sea will be considered until research has shown sustainable stocks that would be made available to Inuvialuit first.