Pollutants entering the Pacific Ocean from the U.S. West Coast may be killing hundreds of southern sea otters each year.
Although sea otters normally live for about 15 years, large numbers of dead breeding-age animals have been reported, National Geographic News reported.
Scientists believe the pollutants suppress the sea otters' immune systems, allowing them to become more susceptible to infectious diseases.
Conservationists told NGN the deaths could erase decades of conservation efforts that have helped restore the population to about 2,500.
Sea otters were hunted to the brink of extinction during the 18th and 19th centuries, but they have been protected by the U.S. Endangered Species Act since 1977.
Lillian Carswell, a Santa Cruz, Calif., biologist told NGN scientists have not yet determined the precise reasons for the deaths.
Copyright 2006 by United Press International
Related stories:
Unravelling the mystery of the kitty litter parasite in marine mammals
Researchers at California Polytechnic State University have discovered what may be a clue to the mystery of why marine mammals around the world are succumbing to a parasite that is typically only associated with cats. The key may just be the lowly anchovy, according to research presented today at the 108th General Meeting of the American Society for Microbiology in Boston.
Is that sea otter stealing your lunch -- or making it?
Hunted to near extinction, sea otters are making a steady comeback along the Pacific coast. Their reintroduction, however, is expected to reduce the numbers of several key species of commercially valuable shellfish dramatically, such as sea urchins and geoducks.
Sea otter study reveals striking variability in diets and feeding strategies
Ecologists have long observed that when food becomes scarce, animal populations exploit a wider range of food sources. So scientists studying southern sea otters at different sites in California's coastal waters were not surprised to find that the dietary diversity of the population is higher where food is limited. But this diversity was not reflected in the diets of individual sea otters, which instead showed dietary specialization in response to limited food.
Why diving marine mammals resist brain damage from low oxygen
No human can survive longer than a few minutes underwater, and even a well-trained Olympic swimmer needs frequent gulps of air. Our brains need a constant supply of oxygen, particularly during exercise.
Large blooms of toxic algae in Monterey Bay are affecting marine animals
Researchers have detected large blooms of toxin-producing algae in Monterey Bay that appear to be poisoning marine mammals and seabirds. Blooms of the algae, which produce a neurotoxin called domoic acid, first appeared in southern California earlier this spring and are now occurring along the Central Coast.
Sea otters pushed out of bay habitat
Alaska's sea otters are in peril after a cold winter on the Alaskan Peninsula has frozen them out of their bay habitat.
Extent of Mercury Pollution More Widespread
Mercury pollution is making its way into nearly every habitat in the U.S., exposing countless species of wildlife to potentially harmful levels of mercury, a new report from the National Wildlife Federation shows.
Global warming might affect Hawaii area
Scientists say many Northwestern Hawaiian Islands might be submerged by 2100 because of global warming, National Geographic News reported.