URBANA As the Asian carp population grows and the threat of the invasive species entering Lake Michigan through one of the Chicago canals is monitored, a University of Illinois researcher believes using two barrier methods is better than one.
Cory Suski experimented with adding carbon dioxide (CO2) into the water as a supplemental tool to work in tandem with the electric fence, which has been used to divert the carp from entering the canal, with the goal of providing a second line of defense.
Suski found that carbon dioxide is quick and effective in repelling fish from an area.
"In one experiment using tanks, we could actually chase the fish with the gas," Suski said. "Once carbon dioxide reached a threshold, fish would 'choose' to leave the area of the tank that had CO2. The fish initially showed signs of being irritated or agitated after exposure, and eventually they lost equilibrium. If fish cannot leave or are slow to leave the carbon dioxide accumulates to a point where it will act like an anesthetic gas used for patients who are undergoing surgery."
Suski knew that CO2 had already been proven to be effective at fish hatcheries. The CO2 was used to move fish from one area to another, making it easier to harvest them. He wanted to see if the technique could be applied to the Chicago River canals and at other vulnerable entry points into the Great Lakes.
In addition to studies quantifying behavior and stress physiology in response to CO2, Suski used a laboratory tank called a shuttle box that contains two chambers and a connecting canal. The level of carbon dioxide can be controlled on either side of the box. Tests were performed on bighead carp and silver carp as well as bluegill and largemouth bass so the effects on native species of fish could be confirmed. CO2 had the same effect on all four species.
"What we learned is that CO2 does not appear to be species specific," Suski said. "This is go
|Contact: Debra Levey Larson|
University of Illinois College of Agricultural, Consumer and Environmental Sciences