Black carp, one of four invasive carp species in North America, have entered the Mississippi River basin.
A new multi-year report from the US Geological Survey (USGS) found that the Black Carp species in the Mississippi River Basin now covers the entire Mississippi River between New Orleans near Keokuk and the southeastern edge of Iowa.
The black carp is a large fish endemic to parts of East Asia, typically growing over three feet and weighing over 100 pounds. The fish was intentionally introduced to the states in the 1970s as a pest control tool for aquatic snails in fish ponds. The population quickly got out of control.
The study analyzed the “ear stones” or “otoliths” of more than 200 Black Carp between 2011 and 2018 to distinguish whether they were wild or farmed.
Patrick Kroboth is a fish biologist at USGS’s Columbia Environmental Research Center in Columbia, Missouri, and co-author of the study. Biological invasions. According to him, carp ear stones, among other methods, are central to their findings.
“As the fish grows,” Kroboth explained, “this calcified structure stores some of the microchemistry of the water around that fish—the environment it lives in, it’s trapped there.”
Although the presence of Black Carp has previously been reported in part of the Mississippi River basin, studies conclude that the population is now self-sustaining.
Black carp is a molluscivore, meaning it eats mainly snails, mussels and clams, among other molluscs. Kroboth said that poses a risk to the Mississippi River and its tributaries.
“Many North American mussel species are threatened and endangered. That’s obviously a concern,” he said.
Credit: USGS. https://www.usgs.gov/media/images/wild-black-carp
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In 2003, the first non-captive Black Carp were identified in southern Illinois Oxbow Lake adjacent to the Mississippi River. Previously, commercial fishermen in Louisiana reported catches in the Red and Atchafalaya rivers in the 1990s.
Brad Parsons with the Mississippi Interstate Cooperative Resource Association said biologists have long suspected black carp live in the basin, and the priority now is figuring out how to manage the pest.
“The fact is, fish don’t understand and aren’t bound by political boundaries,” Parsons said. “A fish that is in the Mississippi River one day may be in the Ohio River one day.”
https://www.usgs.gov/media/images/black-carp-observations-mississippi-river-basin
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In addition to the main body of the Mississippi River, the Black Carp range includes most of its tributaries: the Cumberland, Illinois, Kaskaskia, Missouri, Ohio, Tennessee, Wabash, and White rivers.
Parsons said invasive species management in the Mississippi River will require a collaborative and multi-pronged approach to effectively curb the existential threat posed by carp.
“Our native species are incredibly resilient. They’ve been here for a long time,” Parson said. “But they’re facing a full-frontal attack. And you know we don’t need more, new challenges to throw into the mix here.