Hundreds of fish dying in Clear Lake

Hundreds of carp carcasses have been found in and along Clear Lake, a sign that the deadly koi herpes virus may once more be infecting the lake.

In 2008, hundreds of thousands of carp died from the disease in Clear Lake. Last year, thousands of carp died in Lake Mendocino. The virus was suspected, but could not be confirmed in that case.

Lake County officials estimated the number of dead fish found so far in Clear Lake to be in “the low hundreds.”

“It’s not a huge thing,” county spokeswoman Jill Ruzicka said.

The dead fish, first noted Thursday, are scattered here and there throughout the lake and along the shore, she aid.

Carp die-offs occur periodically throughout the world.

When the goldfish relatives are the only dead fish found, the cause is probably the koi herpes virus, fisheries officials have said. Carp, which are an invasive species here, are hardy fish and would be among the last to die if the cause was lack of oxygen from water being too warm or too much algae growth, they say.

The koi herpes virus was first detected in the United States in 1998 and outbreaks have since been identified worldwide, according to the UC Davis Veterinary Medical Teaching Hospital’s website.

Virus infections could be triggered by people releasing their unwanted koi or goldfish into lakes, officials have said.

The disease is suspected of killing thousands of carp in Lake Ming near Bakersfield in 2010 and Lake Kaweah in Tulare County in 2009. Last year, an estimated 500,000 Asian carp died in the Cumberland River below Lake Barkley dam near Nashville.

Asian carp also are an invasive species and efforts have been made to keep them out of waterways.

The common carp is a smaller bottom feeder that is prevalent in warmer California lakes.

The koi herpes virus is not believed to be harmful to humans or other animals.

Lake County officials recommend that dead carp be buried above the high water mark or placed in a plastic bag in the trash can.

You can reach Staff Writer Glenda Anderson at 462-6473 or glenda.anderson@pressdemocrat.com. On Twitter @MendoReporter.