Hey Paddle Forward! My name is Emily Knudson and I am a student at Augsburg College majoring in Environmental Studies and Spanish. I was on the 10 day Mississippi river trip with Liz and some other students who have been posting to this blog, and on that trip we heard a lot about Invasive Asian Carp. The paddlers on the river have had an experience with an Asian Carp hitting their canoe, and Nick Ryan posted last week about how he heard about an electric underwater Asian carp barrier, so I decided to see what I could find about Asian carp on the Chicago River.
As my classmate Rachel mentioned in her previous blogpost, due to waste water and pollution contaminating the water supply intake point in Lake Michigan, it was decided that the direction of the river flow must be reversed. Engineers completed the Chicago Sanitary and Shipping Canal in 1871 which linked Lake Michigan and the Chicago River, effectively reversing the flow of the river and flushing the waste and pollution away from the city. An unintended consequence of this action was that the two distinct ecosystems became connected, creating a pathway for invasive species moving in both directions. Ironically, the water quality in the Chicago River was so polluted that invasive species were unable to spread to this ecosystem.
In recent decades the Chicago River has become a lot cleaner, and although it is still too polluted for humans to swim in or even touch, Asian carp have adapted to this ecosystem. The Asian Carp are an invasive species originally imported into the United States to control algae growth in Southern fish farms in the 60’s and 70’s. Since then have moved up the Mississippi majorly disrupting the native ecosystems and outcompeting native species. Carp are filter feeders that can grow up to 50 pounds and filter the water so thoroughly that there is not enough food for the native species. If carp swim up the Chicago River (as they are currently doing) and get into Lake Michigan, the lake’s native species will suffer greatly and the carp will have to opportunity to spread to even more bodies of water.
The carp have now moved within 50 miles of the lake, but an underwater electric fence has so far halted their advancement. The U.S. Army Corps of Engineers constructed the electric fence under the canal in 2002 and it is the first of its kind to be implemented. The U.S. Fish and Wildlife service annually completes “carp corral” surveys and has recently noted that at 100 miles downriver from the lake, the Carp population has more than doubled in just one year. While completing the surveys, the movement of the boats stirred the carp causing them to jump out of the water with such velocity that they have broken surveyors noses and damaged boats.
The electric fence is made up of bundles of steel cables that stretch along 54 feet of the canal, releasing one volt of charge per square inch of water. If people were to touch the water with their hand they might feel a tingle or nothing at all, but the Corps is still trying to determine what would happen if a person were to fall into the water. Although research is being done to discover what would happen if someone fell in the river, it is somewhat alarming that they have already begun using this technology without fully knowing the consequences it could have. So far the barrier has prevented carp from moving any farther upriver, but other ecological impacts of the electric fence are still being studied.
A silver carp jumped into one of our boats...watch this video!
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