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Mississippi River

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2 years ago

Asian carp linked to decline of native fish in Mississippi River

TomoNews US
TomoNews US
TRAVERSE CITY, MICHIGAN — New research has linked invasive species of Asian carp to a decline of native sport fish in the Mississippi River and some of its tributaries.

According to a study published in the journal Biological Invasions, there are four types of Asian carp — grass, bighead, silver and black carp — in this river system.

The study focused on the silver carp because the species is more abundant in the Upper Mississippi, where the U.S. Army Corps of Engineers has been collecting data on fish for two decades.

Asian carp were originally introduced to help clear out algae and weeds in sewage ponds and fish farms in the 1960s and 1970s. They escaped, entered the Mississippi River and started migrating north.

The study suggests that this may have led to a decline of native sport fish such as the yellow perch, bluegill and white and black crappie during early life stages due to a dearth of plankton, which both silver carp and sport fish compete for.

While analyzing fish data between 1994 to 2013, researchers found that the number of sport fish had declined by roughly 30 percent in infested areas of the Mississippi and Illinois rivers.

Meanwhile, the study found that the number of native sport fish had increased by approximately 35 percent in sections of the Mississippi River farther upstream where the Asian carp had not arrived.

Researchers considered other factors such as flooding, water temperatures and sediment pollution, though none of them were found to have had a significant impact on native sport fish population.
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