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.

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 up to 6 tons, are fast-moving and difficult to track. They are the most widely distributed mammals on Earth besides humans.

The International Union for the Conservation of Nature, a nonprofit group that maintains a frequently updated global list of endangered and threatened wildlife, lists the status of orcas as “data deficient.” The union is involved in an assessment of orca populations around the world to determine what their status should be.

The U.S. government is concerned enough about the animals that ply the waters of Washington’s Puget Sound and San Juan Islands 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 played roles in the decline of the Northwest’s orcas.

According to the National Marine Fisheries Service, an arm of the federal National Oceanic and Atmospheric Administration, the southern resident orca population, the best studied wild animal population in the world, has fluctuated considerably since researchers began studying it in earnest some three decades ago. In 1974 the group comprised 71 whales but then spiked to 97 animals by 1996. Since then the population fell below 80 and has remained around that level ever since.

Orcas are susceptible to pollution and suffer from diseases and reproductive disorders accordingly. Many scientists consider orcas an “indicator species” regarding the health of marine ecosystems in general. If orcas are in decline, the rest of the ocean is likely in trouble, too.

Increased concern about the health of marine ecosystems in recent years is good news for orcas, which are dependent on a wide range of fish and marine mammals for sustenance. The preponderance of protected stretches of both ocean and coasts gives orcas a boost in their struggle to stay one step ahead of extinction. If world leaders continue to value marine ecosystems and limit the extraction of seafood species and contamination by pollutants, killer whales will have a fighting chance to keep on as icons of the sea.

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