Is this a "Darwin's Nightmare" scenario?
Invasive Asian carp may be present in the Mississippi River at Twin Cities, DNA testing of water samples reportedly show.
The Minnesota Department of Natural Resources said water samples taken downstream of the Ford Dam in Minneapolis had tested positive for genetic material from silver carp, the Columbus Dispatch reports.
However, the tests don’t reveal the number of fish present, their size or whether they are breeding, the agency reportedly said.
The Minnesota and St. Croix rivers are also being tested carp.
An extreme example of the impact of invasive fish species on an ecosystem can be seen in the 2004 film "Darwin's Nightmare," about the effect of fishing the Nile perch in Tanzania's Lake Victoria.
The Washington Post quotes park Superintendent Paul Labovitz as saying in a news release:
"These eDNA results are like a smoke alarm blaring. Until we find the source, we have to assume there is a fire. We have to assume Asian carp are here."
Silver carp consume huge amounts of the plankton, which is the foundation of a river’s food chain, and so their spread could cause serious damage to native fish and local aquatic systems.
The silver carp can also jump 10 feet out of the water when startled, endangering boaters.
Asian carp, first brought to the United States from China, have been making their way north from Arkansas for 15 years. They had escaped from southern sewage treatment plants and fish farms on the Mississippi, according to the Post.
Minnesota — along with Michigan, Ohio, Pennsylvania and Wisconsin — afraid that carp will take over Lake Michigan and eventually the Great Lakes, jeopardizing a $7.5 billion fishing and boating industry.
The U.S. Army Corps of Engineers is studying ways to cut off avenues for aquatic species between the Great Lakes and Mississippi River basins, and has undertaken to report by 2015, the Post reports. An electric barrier already exists about 25 miles from Chicago.
But the states want physical barriers put up in the Chicago area and have filed a federal lawsuit demanding immediate action to "physically separate the Great Lakes and Mississippi systems to prevent Asian carp and other species from migrating between the two watersheds."
Minnesota, meantime, has said it will immediately hire a commercial-fishing enterprise to begin netting and searching for the carp below the Ford Dam.
(More from GlobalPost: Illinois wants to end hunger with Asian carp)