Study: Invasive Black Carp Are Established In Mississippi River Basin

Black carp, an invasive fish species in North America, are now known to be established in the wild in parts of the Mississippi River basin, according to a new study co-authored by the U.S. Geological Survey (USGS). The study is the first to identify an established population—meaning they are naturally reproducing and living to adulthood—of wild black carp in any location across the U.S.

Black carp are one of the four major Chinese aquaculture carp originally imported into the United States. The others are silver carp, bighead carp and grass carp. Those three have already been documented by the USGS and partners as established in the Mississippi River basin. This group of fish was previously known in the United States as “Asian carp” and is now referred to as “invasive carp.” Black carp can grow quickly and reach more than 3 feet long. They prey on species such as snails and mussels and pose a risk to many already imperiled native mussels in this region. Mussels support ecosystem health by improving water quality—they filter out bacteria, algae and pollutants as they breathe and feed—and provide food and nutrition for other species.

Knowledge of the extent of invasion can help inform federal, state and local agencies as they develop control strategies, mitigate effects and consider plans and limitations on the use or transportation of live black carp.

Black carp, which are native to east Asia, were first imported to control snails in fish farms where fish are bred. Snails host parasites that can harm channel catfish, hybrid striped bass and other fish that are important human food sources and support the regional economy. Black carp were imported from Asia to the U.S. multiple times beginning in the 1970s. The use of black carp in aquatic environments is regulated and requires permits; there isn’t a clear understanding of how black carp escaped those settings. It’s thought that rains flooded containment ponds and allowed them to escape into river systems. Some states ban possession of black carp, and importation of black carp into the U.S. has been prohibited since their 2007 listing as an injurious species under the Lacey Act.

“While prior studies have indicated that wild black carp might be established in parts of the Mississippi River basin, this is the most comprehensive study and the first research to provide strong evidence that they are present and sustaining on their own,” said Patrick Kroboth, a research fish biologist with the USGS and co-author of the study.

“This study finds that in the area examined, wild black carp have naturally reproduced, there are multiple ages present, carp are living to adulthood, and the population primarily consists of fertile fish that are capable of reproducing,” Kroboth said. “This suggests that the environment has suitable conditions for black carp’s entire life cycle.”

The study’s authors examined black carp that were captured by the public or state and federal agencies between May 2011 and September 2018. The fish were examined for characteristics such as size, age, the environments in which they have lived and whether fish were reproduced in the wild or in controlled settings.

“When an invasive species becomes established, eradication can be difficult, but it can also be challenging to collect robust information during the onset and early stages when abundance is typically low,” said Gregory Whitledge, a professor with the Center for Fisheries, Aquaculture, and Aquatic Sciences at Southern Illinois University and the lead author of the study. “This research includes the largest sample size and is the most robust analysis of wild black carp in the Mississippi River basin, helping inform those making decisions to curtail further expansion.”

The Mississippi River basin covers more than 1,150,000 square miles and includes 32 states and small parts of two Canadian provinces. The river originates in northern Minnesota and flows south to Louisiana. Black carp have been observed in several locations, but exact species abundance and distribution isn’t currently known because there are limited sampling efforts targeting black carp, and the probability of catching them in the large rivers they inhabit is low.

The research was recently published in Biological Invasions. In addition to Southern Illinois University and the USGS, authors include Missouri State University, the Missouri Department of Conservation and the U.S. Fish and Wildlife Service.

When a black carp is captured in the wild, it can be reported to the USGS Nonindigenous Aquatic Species database. That tool compiles information on and can be used to track the status of other aquatic invasive species as well. The USGS is involved in many invasive species projects across the U.S. and its territories. Learn more by visiting the USGS Invasive Species Program website or the USGS invasive carp website.