EarthTalk: Killer whale population not known

Dear EarthTalk: How are populations of the world's orca whales faring these days? Are we still in danger of losing them all in the wild? - J. Witham, Bangor, Maine

The largest member of the dolphin family and a major draw at marine parks, orcas (also known as "killer whales") are highly intelligent and social marine mammals that, because of these traits, have come to be known as ambassadors for nature and marine ecosystems around the world.

But the fact that people love orcas-most of us only ever see them in captivity-has no bearing on how well they are thriving in the wild. Many of their habits are still a mystery to science, as the great black and white creatures, which can grow to 26 feet and weigh six tons, are fast-moving and difficult to track (they are the most widely distributed mammals on Earth, besides humans).

Given this uncertainty, the International Union for the Conservation of Nature, a nonprofit group that maintains a frequently updated global list (the so-called "Red List") of endangered and threatened wildlife, merely lists the status of orcas as "data deficient." IUCN is currently involved in an assessment of orca populations around the world to determine what their status should be.

Orcas may not have a clear-cut conservation status internationally, but the U.S. government is concerned enough about the animals that ply the waters of Washington's Puget Sound and San Juan Islands (known as the "southern residents") to put them on the federal endangered species list. Chief among threats to orcas there is loss of food supply, mostly West Coast salmon populations destroyed by hydroelectric dams and other human encroachment. Habitat loss, chemical pollution, captures for marine mammal parks and conflicts with fisheries have also each played roles in the decline of the Northwest's orcas.