Tuesday, December 24, 2013

Invasive carp could swim with barges through Chicago canal into Great Lakes, research shows

The plan to keep invasive Asian carp out of Lake Michigan may have a major hole in it. Researchers have found that fish can get  through "the electric barrier on the Chicago Sanitary and Ship Canal that is considered the last line of defense to stop an Asian carp invasion," Dan Egan reports for the Milwaukee Journal-Sentinel. A report "by the U.S. Army Corps of Engineers and U.S. Fish and Wildlife Service reveals that fish can be transported across the electrified swath of canal when they get trapped in the wake of a barge." Officials say there is no evidence that Asian carp have broken the barrier, or are near it, but scientists have said that if they get into the Great Lakes, they could severely damage the region's $7 billion annual fishing industry. (Journal photo: the barrier is located near the arch)

Cameras found that "entire schools of fish, not believed to be Asian carp, were recorded swimming through the barrier 61 percent of the time" when a barge came through, Egan writes. The report states: "Initial findings indicate that vessel-induced residual flows can trap fish and transport them beyond the electrical barriers, and that certain barge configurations may impact barrier electric field strength. Additionally, the preliminary (sonar camera) findings identified the potential for small fish (between 2-4 inches in length) to pass the barrier array in large groups, or schools." Still, researchers say it's not yet time to panic: "The closest adult Asian carp found in the Illinois River are about 55 miles from Lake Michigan, and no small Asian carp have been observed closer than 131 miles from Lake Michigan."

Despite those claims, "Water samples taken at the barrier site and in stretches of canal on the Lake Michigan side of the barrier have regularly tested positive for Asian carp DNA during the past four years," Egan writes. "Advocates want the canal physically plugged to stop Asian carp and other unwanted species from swimming freely between the Great Lakes and Mississippi basin." (Read more)

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