As I write, I am listening to the Star Wars “Imperial March” and picturing rows of over-sized, stony-faced fish stomping up the Mississippi River from Illinois to Minnesota. Unlike Darth Vader, Asian carp are not inherently evil, but they are non-native invaders with voracious appetites, no natural predators, and the potential to pillage our Mississippi, Minnesota and St. Croix Rivers like the Imperial Army invading the galaxy.
There are four species of Asian carp: bighead, black, grass and silver carp. As the name suggests, the fish are native to China and Southeast Asia, where they are a dietary staple for many river communities and a favorite dish at restaurants. In the 1970’s, fish farmers in the southern U.S. brought in Asian carp to help clean their ponds, but the fish escaped during flooding and have since taken hold in the Missouri, Illinois and southern stretches of the Mississippi River. They play the role of villain well. Bighead carp can weigh more than 100 pounds and silver carp, a mere 60 pounds at most, leap out of the water as high as ten feet in the air when boats pass by. Search for silver carp videos on YouTube and you will be amused and terrified by the footage of fish crashing into boats, knocking over water-skiers, and flopping in the air like giant, slimy popcorn kernels leaping out of a pan.
Like many of our native fish, Asian carp eat algae and other plankton, but because they are so big they eat a lot, lot more of it. For this reason, they have the potential to quickly knock an aquatic food web out of balance, and in some stretches of the Illinois River, 60% of the river’s fish biomass is now comprised of Asian carp.
Federal and state agencies in Minnesota and Wisconsin have been on the lookout for Asian carp for several years. According to the Mississippi State of the River Report, about a dozen silver and bighead carp have been caught in Mississippi River near Winona and the St. Croix River near Prescott since 1996. Though they have not yet established populations this far north, environmental DNA testing has shown evidence that they might be swimming in the Mississippi below the Coon Rapids Dam, between the Lower St. Anthony Falls and Ford Lock and Dams and below the Hastings Dam. Researchers also found carp DNA in water collected from the St. Croix River south of the Taylor’s Falls Dam and from the Minnesota River just north of Fort Snelling.
The primary recommendations for stopping the spread of Asian carp hinge on strategically closing locks in the Twin Cities metro Mississippi River, installing electric or “bubble” barriers or developing biological controls. The local ad-hoc Asian Carp Task Force also sees a role in the rebel army, however, for Minnesota and Wisconsin residents that fish and boat on the rivers. The State of the River Report urges recreational boaters to avoid using the locks and dams, and the National Park Service and Friends of the Mississippi River also caution anglers to be sure they know where their bait comes from, as baby carp look a lot like minnows.
To learn more about the health of the metro Mississippi River, visit www.StateoftheRiver.com or attend a special presentation for Washington County residents on Dec. 4, 7pm at Hidden Harbor in St. Paul Park. More information and RSVPs to firstname.lastname@example.org or 651-275-1136 x.35.