Wildlife on the Brink: Orca (Killer Whale)

SCIENTIFIC NAME: Orcinus orca

STATUS: Proposed threatened (Puget Sound population)

HABITAT: Coastal waters and open ocean

LIFE HISTORY: Highly social; individuals form pods that average between 5 and 30 whales. Each pod is led by a female and has its own distinct set of calls.

THREATS: Pollution, overfishing, general degradation of marine habitat

RANGE: Worldwide; unique resident populations in areas such as Puget Sound

CURRENT POPULATION: Global population uncertain -- estimated minimum 50,000; 84 in Puget Sound

Perhaps the best-recognized "whale" in the world, the killer whale, or orca, is actually a member of the dolphin family. Orcas live in matriarchal societies and hunt in packs, chasing down everything from sharks to whales.

Being at the top of the food chain might seem like an advantage, but it also exposes orcas to large amounts of pollution. Toxic chemicals like PCBs get concentrated in the fatty tissues of smaller fish and work their way up the food chain, collecting in the bodies of top predators like orcas, which now rank among the most contaminated marine mammals in the world.

The year-round orca population in Puget Sound, off the coast of Washington State, has dropped 20 percent since 1996, and scientists believe that human activities such as pollution, overfishing, oil spills and undersea noise are the likely cause. The Center for Biological Diversity estimates that if current trends continue, this southern resident orca population will be extinct within 100 years and possibly as soon as 30 years.

In 2002, NRDC supported the listing of this population as a "depleted stock" under the Marine Mammal Protection Act and urged the National Marine Fisheries Service to protect the group under the Endangered Species Act. In December 2004, the federal government proposed listing the Puget Sound orca as a threatened species.

Photo: orca © NOAA/Dept. of Commerce