Scientists are scrambling to find the cause of the mounting death toll among seals along a stretch of the California coast north of San Francisco.
Since April, about 80 dead or dying harbor seals have washed up on Point Reyes National Seashore beaches, apparently dying from an infection caused by a virus.
“This is the largest stranding we’ve seen in the 20-plus years I’ve been out here surveying seals,” said Sarah Allen, ecologist at the seashore.
Point Reyes is home to about 5,000 seals, which live in nine colonies, some of them very remote. Normally, Allen sees fewer than 20 dead seals a year.
“Now, we’re getting about half dozen a week,” she said.
The cause “seems to be viral,” she added. “It’s not human-induced as far as we can tell. It’s something in their environment.”
“The way this thing is operating is kind of strange. We’re scratching our heads,” said Joe Cordaro, wildlife biologist for the National Marine Fisheries Service in Long Beach. He said some of the seals have died from pneumonia, but the “bacteria is so heavy it has masked the underlying cause.”
He speculated that the seal colonies could be becoming too congested, causing a disease to run rampant.
The illness is affecting the adult seals - not the pups - possibly with weaker immune systems, Cordaro added.
Researchers are having difficulty getting useful tissue samples because most of the animals washing up on the beaches are badly decomposed.
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