Results reveal that the invasive species may not be as immediately threatening as certain local politicians and activists had previously argued.
No Asian carp turned up after a massive fish kill last week in the Chicago-area canals, officials announced Tuesday, suggesting that the threat of the invasive species isn’t as immediate as was feared. While more than 40 species of fish were found, none were the high-flying fish.
Regional politicians had argued the canals threatened to let the menacing fish into the Great Lakes.
Illinois Department of Natural Resources workers poisoned a two-mile stretch of the Little Calumet River and spent five days scooping up and sorting through the resulting 100,000 pounds of dead fish. The $1.5 million operation was the second such fish kill; a similar $3 million effort conducted in December turned up only one Asian carp.
Meanwhile federal biologist Duane Chapman has conducted research that found Asian carp tend to sink when poisoned, and told the Milwaukee Journal Sentinel that it could take time for any poisoned carp to surface.
Asian carp have infested large stretches of the Mississippi and Illinois rivers in recent years, touching off a political battle over whether the Chicago Sanitary and Ship Canal should be sealed off from Lake Michigan to prevent the fish from getting into the lake. Scientists fear that the invasive species could drastically alter the Great Lakes ecosystem and devastate its $7 billion sportfishing industry.
In March, the U.S. Supreme Court rejected an effort by Michigan’s attorney general to force such a closure—an effort that drew legal support from Ontario and every other Great Lakes state but Illinois.
Water tests using a recently developed technique known as environmental DNA or eDNA had turned up evidence of Asian carp near Lake Michigan.
John Rogner, co-chair of the Asian Carp Regional Coordinating Committee that oversaw last week’s fish kill, said more work remains to be done to determine the threat that Asian carp pose.
“We will now look at the entire body of evidence collected thus far, including eDNA sampling results and all of our conventional sampling with nets and electrofishing gear to see if we can draw any further conclusions about the risk of invasion and establishment of Asian carp in Lake Michigan through the Chicago Area Waterway System,” Rogner said.
Steve Kellman is a Circle of Blue writer and reporter. Reach him at circleofblue.org/contact.