Humpback whales are increasing in numbers in the northern Pacific Ocean, although they are still scarce off the coast of Asia. (NOAA Fisheries/Associated Press)

Humpback whales appear to be returning from the brink of extinction in the North Pacific Ocean, a new study shows.

The study, conducted by an international whale watching organization, estimates there were 18,302 humpbacks in the North Pacific between 2004 and 2006, compared with an estimated 9,819 in 1991-93 and 1,400 in 1966.

Most of the current population winters off the coasts of Hawaii and Mexico, and feeds off the coast of northern British Columbia, Alaska and the nearby Bering Sea and Aleutian Islands.

Of concern is the Asian coasts, where humpback numbers are still scarce, the study says.

The study was conducted by SPLASH (Structure of Populations, Levels of Abundance and Status of Humpbacks), an international organization that tracks humpbacks throughout the North Pacific. More than 400 researchers from 10 countries, including Canada, participated in the whale count.

Experts say bans on humpback hunting have helped the population recover.

Humpback whales have been protected by the International Whaling Commission since 1965 in the North Pacific and 1955 in the North Atlantic, according to Fisheries and Oceans Canada.

Canada is one of many countries that bans whaling, while the Canadian government has included the North Pacific humpback as one of the threatened and protected animals listed under the Species at Risk Act.

Despite the hunting bans, the Canadian government says humpbacks are still at risk because of over-fishing of their prey — including tiny crustaceans and small fish. The whales also can become entangled in the fishing nets of commercial trawlers and drown.

In addition, the whales face risks from exposure to the growing number of oil spills caused by the increasing amount of tankers in coastal areas, the government says.