Scientist: Carp may have been planted near Lake Michigan
TRAVERSE CITY, Mich. -- A 3-foot-long Asian carp discovered in a Chicago waterway near Lake Michigan appears to have spent most of its life there and may have been planted by humans who didn't know what type of fish it was or the environmental risk it posed, researchers said Thursday.
Tests of chemical markers in the bighead carp suggest it was not a recent arrival to the waterway and probably did not get there by evading an electric barrier meant to prevent the species from infesting the Great Lakes, said Jim Garvey, a fisheries biologist at Southern Illinois University Carbondale.
He acknowledged the findings were not certain because of incomplete data and were based on a number of assumptions.
"But it is very plausible that this fish originated in the Illinois River and then moved or was transported to Lake Calumet or Lake Michigan during the early portion of its life," Garvey said.
The 20-pound bighead was netted June 22 in Lake Calumet on Chicago's South Side, about six miles from Lake Michigan. It was the first actual Asian carp seen above the barrier, although scientists have reported numerous findings of their DNA in waterways between the barrier and Lake Michigan.
The discovery intensified calls by environmentalists and neighboring states to close shipping locks on the waterways and separate the man-made connection between the Great Lakes and Mississippi River basins. Michigan, Wisconsin, Ohio, Minnesota and Pennsylvania have filed a federal lawsuit seeking those actions.
Shippers and other Chicago-area industry groups say such measures are unnecessary and would damage the region's economy.
Tests on the bighead carp found in June were conducted at the university's Fisheries and Illinois Aquaculture Center. Researchers examined its tiny inner ear bones, known as otoliths.
Otoliths contain fingerprints of calcium and other chemicals that are unique to the waterways in which they live, Garvey said. Layers of the chemicals build up in othliths similarly to tree rings, enabling scientists to identify a fish's age as well as the water bodies in which it has lived.
The analysis suggests the bighead spent most of its life in Lake Calumet or even Lake Michigan, which have similar water chemistry, Garvey said. But chemicals in the part of the otolith that developed in roughly its first year came from another waterway -- one with chemistry similar to the Mississippi and Illinois rivers, he said.
The exact water body from which the fish originated hasn't been pinpointed, he said.
John Rogner, spokesman for the Illinois Department of Natural Resources, said the report reinforces the possibility that humans placed the carp in Lake Calumet. Releasing live fish is a cultural ritual for some people, he said. Or it might have been dumped from an angler's bait bucket.
"We're not suggesting that anyone did this maliciously," Rogner said. "At that early age, it's very easy to misidentify Asian carp with other commonly used bait fish."
The agency will be testing for Asian carp DNA at about 60 Chicago-area bait shops in September and teaching owners how to spot young bighead and silver carp -- the two species threatening to reach the Great Lakes, he said.
Some biologists say if they become established in the lakes, the voracious filter feeders could starve out prey fish on which popular sport and commercial species depend.
Joel Brammeier, president of the Alliance for the Great Lakes, said the findings about the bighead did not mean the barrier was blocking the path of other Asian carp.
"One fish did not leave behind the clouds of DNA that have been turning up in the Chicago waterway the past year," he said.
Lisa Frede, regulatory affairs director for the Chemical Industry Council of Illinois, said the university's discovery "should serve as yet another warning to alarmists calling for the total shutdown of the Chicago locks and complete hydrological separation, that perhaps their knee-jerk reactions are unwarranted."