Mississippi Floods Could Spread the Invasive Asian Carp

Like all great supervillains, the Asian carp have their origin story. The fish were imported from Asia—where they’ve been raised in aquaculture for thousands of years—to the Midwest in the 1970s, where they were used in fish farms. When the waters around the Mississippi flooded in the spring, however, so would those farms—and at least some of the carp were able to escape the river system, where they’ve since established themselves. Since then the Asian carp have been making their way north towards the Great Lakes—and being the marine equivalent of vacuum cleaners, they could sweep the lakes clean of other life forms if they manage to gain a finhold. And in the meantime, they do this:

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The government is spending tens of millions of dollars to prevent the carp from being the latest alien species to invade the Great Lakes. But the lakes aren’t the only territory in danger of being overrun by the fish, which can grow up to 110 lbs. Scientists are worried that the unusually heavy spring floods along the Mississippi River may free a new battalion of Asian carp:

Duane Chapman, a U.S. Geological Survey biologist and Asian carp expert, says the fish are likely to show up in places where Mississippi floodwaters intruded. They can weigh up to 100 pounds grow 4 feet long and live for 25 years. (See the Top 10 Historic U.S. Floods.)

They could be crowding out food sources of native species for decades. “I think there is a very serious issue here,” said Chapman. “We may now be finding them in lakes, ponds, bayous, anywhere the river water went. Those things will be full of carp now.”

That’s not a good sign. The Mississippi’s spring floods have inundated an estimated 6.5 million acres along a 1,000 sq. mile stretch of the river from Missouri to south of Louisiana. The flooding has backed up farmland and catfish farms—and even though the brackish water would discourage most freshwater species, the Asian carp are more than capable of surviving the floods:

In Mississippi, ponds holding farmed catfish have taken a heavy toll from backwater flooding. The industry says it may take a year to scrub out the ponds and remove much that was left behind, including Asian carp. They also will have to restock because their crop either swam away in the flood or died because of muck and foul water entering the ponds.

The fish thrive in fast-moving water, said Ruben Keller, a lecturer in environment studies at the University of Chicago who has worked extensively on Asian carp with the National Invasive Species Council. “They spawn in high water events like the flood,” Keller said. “This will produce many more carp.”

Given the sheer amount of destruction wrought by the floods, there’s not a whole lot that ecologists can do to prevent escapee carp from making a new home in the Mississippi system. In fact, it might be time to reconsider the war against the Asian carp and other invasive species. In a world that has been as ecologically mixed up as ours—thanks to climate change and human development—the distinction between invasive and natives doesn’t really mean that much anymore. After all, when it comes to invasives, Asian carp are nothing next to another species that has proliferated into the billions, spread to every corner of the world and displaced other animals and plants and sucked up every available natural resource. They’re called human beings.