Asian Carp Eggs Found in Upper Mississippi River, USGS

U.S. Geological Survey scientists have found Asian carp eggs in water samples collected in 2013 from the Upper Mississippi River.

Asian carps have spread rapidly in Mississippi and Illinois River systems since the past few decades, but scientists weren't expecting the fish eggs to be as far north as Lynxville, Wisconsin. The eggs and late-stage embryo were some 250 miles upstream from the usual reproductive populations.

The samples were collected mid-May and mid-June, 2013, USGS said.

"This discovery means that Asian carp spawned much farther north in the Mississippi than previously recorded," said Leon Carl, USGS Midwest Regional Director, according to a news release. "The presence of eggs in the samples indicates that spawning occurred, but we do not know if eggs hatched and survived or whether future spawning events would result in live fish."

Researchers found the eggs in samples obtained from seven locations in the Mississippi River.

Asian carps are native to Eastern Russia and China and include bighead carp (Aristhythys nobilis), silver carp (Hypothalmichthys molitrix), black carp (Mylopharyngodon piceus), and grass carp (Ctenopharyngodon idella).

The fish are a nightmare for the native fish population because they can eat a huge amount of plankton and can grow big. Bighead carp can weigh as much as 110 pounds. Their enormous size prevents predators from killing them.

A preliminary analysis by the scientists at USGS has shown that the fish eggs belong to the notorious Bighead carp. The team has conducted genetic analysis of the fish eggs to confirm their findings. Results of the analysis are expected in the next few days.

"Invasive Asian carp could pose substantial environmental risks and economic impacts to the Upper Mississippi River if they become established," Carl said in a news release. "Further research will help us to better understand their habitat requirements and inform integrated control efforts." 

Scientists are sure how the fish managed to reach Lynxville. "Were they carried inadvertently in bait buckets? Understanding how they got there is important in stopping their spread in the future," Cindy Kolar, a science adviser on invasive species for the USGS told National Geographic.