A lot of people, from scientists to fishermen, have long suspected that at least some Asian carp have already found their way into the Great Lakes, though not yet in numbers large enough to establish breeding populations.
That suspicion was given credence recently when a scientific report written by experts who pioneered the use of genetic data to search for the aggressive fish essentially debunked government claims that many of the positive Asian carp DNA “hits” recorded in recent years came from sources like the excrement from birds that fed on carp in distant rivers.
And while the same scientists who authored the recent report say there is reason to hope the carp won’t reach critical mass, experience has shown that at every turn, the carp have gone further and established breeding populations faster than anyone thought they could.
That means efforts to sever all aquatic links between Chicago-area waterways where there may be carp and Lake Michigan must continue; anything less is a risk we can’t afford.
In the report, laboratory analysis turned up 58 positive hits for bighead or silver carp in the Chicago Area Waterway System — a network of rivers and canals linked directly to Lake Michigan — and six in western Lake Erie. Some of the Chicago DNA was found in Lake Calumet, where a live bighead carp was caught in 2010.
Sampling by the U.S. Army Corps of Engineers and other federal agencies also yielded positive results in the Chicago waterways. But while the government team acknowledges the presence of Asian carp genetic fingerprints, it disagrees that they necessarily signal the presence of live fish.
The issue is significant because it could influence the debate over whether to seal off Lake Michigan from Chicago-area waterways, a mammoth engineering task that would cost billions and take years to complete.
Under pressure from Congress, the Army Corps of Engineers has pledged to offer options for preventing species migrations between the Great Lakes and the Mississippi River watershed later this year.
That effort absolutely must continue. We’ve seen the damage other invasive species have already done to the Great Lakes, and the carp has the potential to outdo them all. Scientists say silver and bighead carp gorge on plankton - microscopic plants and animals that virtually all fish eat at some point — and could collapse the food chain.
That can’t be allowed to happen. Those of us who live on the Great Lakes have an obligation to protect the resource. We’ve flunked a lot of tests in the past, but this one is too big to fail.