Bacteria cause Lake Zurich carp deaths

Bacteria common to water was found to have killed hundreds of carp that washed ashore early last month in Lake Zurich.

Having far fewer carp won't be a bad thing for Lake Zurich, said Frank Jakubicek, an Illinois Department of Natural Resources fisheries biologist. He said carp often cause problems for desirable sport fish by disturbing nest sites in lakes.

"We'd prefer that carp disappear," Jakubicek said Friday.

State natural resources officials collected the dead carp at Lake Zurich - on the namesake village's northwest side - after they began washing ashore around July 2. Officials said the carp were 4 to 5 pounds and up to 20 inches long.

Jakubicek said four of the carp were sent for testing at the U.S. Fish and Wildlife Service facility in Onalaska, Wis. He said the carp were barely alive and placed on ice for the 245-mile overnight package delivery.

Test results that recently became available show the carp died from Aeromonas hydrophila, a bacteria present in all freshwater environments. Jakubicek said the Lake Zurich carp likely were vulnerable to the bacteria because they were weakened from spawning.

Rich Sustich, president of the Lake Property Owners Association of Lake Zurich, said the bacteria finding confirmed his group's position that the carp didn't die from aquatic weed treatments or chemical contamination.

"We knew instinctively this was not a chemical issue," Sustich said.

Jakubicek said the carp were studied because viral hemorrhagic septicemia was reported in some fish in Lake Michigan last month. Officials wanted to make sure the fish disease had not spread.

Known as VHS, the deadly virus is considered a threat to at least 25 fish species including yellow perch, bluegill and northern pike. Those fish are among the 14 species in the 250-acre Lake Zurich.

Officials estimated there were 1,000 to 1,500 carp in Lake Zurich before they began dying. Jakubicek said the death of almost all of the carp was part of nature taking its course.

Lake Zurich's sport fish would be expected to increase with fewer carp around them.

"People spend a lot of money trying to get rid of carp in their lakes," said Jakubicek.

Fish kills are not unusual. Hundreds of crappies and carp died off in June at suburban lakes, according to the Lake County Health Department.

Carp are regarded as bottom-feeders and not worth eating in the United States.