All species of large whales have been drastically reduced in numbers by centuries of intensive whaling. An indefinite ban by the International Whaling Commission on commercial whaling of all large whales gradually went into effect following the 1984–85 season, and large portions of ocean have been designated whale sanctuaries. With these and various other protective efforts, some species have begun to return to acceptable numbers, but others, especially the right and blue whales, are still rare and endangered. After decades of protection the number of E Pacific gray whales seems to have returned to its estimated prewhaling level. Only the small minke whale exists in populations great enough for sustainable whaling to be considered. Whale products include whale oil, sperm oil, spermaceti, ambergris, and whalebone, as well as meat, bone meal, and liver oil. Natural and synthetic materials have replaced all whale products in the United States. See separate entry on whaling for more information.