Friday, February 02, 2007
Bacterial disease eyed in sea lion deaths
CORVALLIS, Ore. - Scientists say a bacterial disease that can affect mammals, including humans, may be behind an increase in sea lions found dead on Oregon beaches recently. But more volunteers are looking for marine mammals, which also could be partly behind the higher figures, said Jim Rice, an Oregon State University research assistant who coordinates the Oregon Marine Mammal Stranding Network."I think 90 (California sea lions) is a pretty good estimate for what we've had this past year," Rice said. He said the die-off isn't large considering the increase in the sea lion population since it became federally protected in 1972.But he said leptospirosis and other diseases are reasons for people and dogs to avoid the dead animals on shore. Federal law prohibits approaching live mammals on the beach. Some people try to help stranded sea lions, seals and other mammals.Rice urged people instead to call the network and report their findings. Leptospirosis, which leaves sea lions emaciated, can infect someone through broken skin and mucous membranes."You generally have to come into contact with the animal or its bodily fluids," Rice said. "If someone got bit, or touched an animal with their bare hands, that could be enough potentially."There are up to 100 documented cases in humans in the United States each year, mostly involving trappers, slaughterhouse workers, agricultural workers and soldiers.Symptoms include headaches and nausea, but serious cases can lead to kidney failure and liver damage."The disease is probably underreported. It varies in its severity," said Jerry Heidel, director of the OSU Veterinary Diagnostic Laboratory. About a third of the dead sea lions tested have come up positive for the disease.Some people, especially fishermen, aren't overly chagrined at the prospect because sea lions steal hooked salmon and gather at the base of Bonneville Dam to catch the fish as they school up waiting to go over the fish ladders to spawning grounds.Rice said gunshots are the suspected in deaths of dozens of cases he sees each year. The federal government says it will consider a petition to remove or kill especially troublesome sea lions at the dam.In 2006, the Oregon Marine Mammal Network responded to about 300 stranded or dead animals. That doesn't include healthy animals just resting.Most of those calls were for California sea lions, but whales and seals also were reported. Rice said there would have been a spike in reports even without the extra eyes, which include three newly created state beach ranger positions. In 2005, 34 California sea lions were reported. The previous year there were 82. "The disease was suspected in a lot of the cases in 2004, but many of those animals were not tested," Rice said.