Theories abound about the cause of the recent carp die-off around Clear Lake. They range from herbicide poisoning, a fish virus and decaying weeds that use up oxygen in the water. A number of fishermen are concerned other fish such as bass, crappie and catfish will die.
The official cause of the die-off remains unknown but it is suspected that it’s from a virus called KOI Herpes Virus. Hundreds of dead carp have been washing up on beaches around the lake.
While the die-off has been bad, it’s nothing compared to the massive die-off that occurred in 2008 when thousands of carp died. In fact, there were so many dead carp back then some lakeside residents used tractors with front-end loaders to gather up the dead fish. The cause of that die-off was also determined to be the herpes virus after several carp were examined in a laboratory.
The Department of Fish and Wildlife (DFW) classify carp as a non-game fish and they are considered a hearty fish. They can survive water temperatures that range from freezing to more than 90 degrees. Carp also have the ability to absorb what is called “atmospheric” oxygen. What that means is that if the oxygen levels are too low in the water, carp can still breathe by sticking their noses above the surface and inhaling oxygen from the air. This dispels the theory going around that the carp are dying from a lack of dissolved oxygen (DO) in the water. Actually, DO levels presently are higher than normal.
According to DFW fishery biologist Ben Ewing, the answer as the exact cause of death of the carp should come in a couple of weeks. He said that a carp can carry the virus in its body for several years. Once infected with the virus, the mortality rate is nearly 90 percent and most of the carp die within a few days. The good news is the herpes virus doesn’t infect other species of fish such as bass, catfish or crappie. Even the hitch or other fish native to the lake aren’t infected by the virus.
Regardless of what is killing the carp, there is nothing the DFW can really do to stop it. Clear Lake is just too large to treat. Most likely the carp die-off will run its course the next few weeks. As long a the virus doesn’t infect the other fish in the lake, especially the native and game fish, no one really cares. Carp aren’t the most loved fish in America.
I took a drive around the lake on Sunday and the dead carp are widely scattered. Several bass fishermen said that there are even dead carp in the middle of the lake. A bigger problem is what lakeside residents can do with the hundreds of dead carp washing up on their beaches. They have been told to bury them but several residents are reporting the ground is too hard to dig in. If left on the beach to rot, the stench will drive many people from their homes.
Carp aren’t native to the United States, but to Europe and Asia. It is thought they were first introduced into United States in 1830 in New York as a food fish. They arrived in California in 1872 when five carp were placed in ponds in Sonoma County. From there, they rapidly spread throughout the state and it is believed they arrived in Clear Lake around 1900.
Carp are the most widely eaten fish in the world, with more than 200,000 tons consumed annually. Carp provide more protein worldwide than cattle. Eastern Europe and Asia are the primary areas where carp are a popular food fish, the reason being they are high in protein and low in fat.
Carp can thrive in just about any type of freshwater. They are omnivores, meaning they will eat both fish and vegetation. Many people don’t know that a carp has large molars in the back of his mouth that it uses to grind up its food. A female will produce approximately 300,000 eggs during a single season. They are also a long-lived fish. The oldest carp on record lived to age 47. Many live to be 20 years old.
Whereas most people think carp are a trash fish, there are individuals who fish for them and consider them excellent fighters. In fact, there are carp tournaments, including several held at Clear Lake. Carp die-offs aren’t unusual at Clear Lake and there will be others in the future.
On the bass fishing front, the Western Bass Clear Lake Open starts today and runs through Friday. There are 98 boats in the pro/am tournament. Weigh-ins take place at the Konocti Vista Resort starting at 2 p.m. each day.
