Ball State Study: More Fish Species Living In Ohio River

The Ohio River has seen a marked increase in the number of fish species over the past five decades.

The Ohio River at Lawrenceburg, Indiana. File photo

(Muncie, Ind.) – Improving water quality of the Ohio River may be behind a rise in the number of freshwater fish species present in the waters.

A study by Ball State University biology professor Mark Pyron determined that the variety of species in the river has evolved dramatically since the 1960s. The number of species richness varied from 31 to 90 each year, increasing over time.

Pyron used 57 years of rotenone and electrofishing fish collection survey data from the Ohio River Valley Water Sanitation Commission. He conducted the study -- "Long-term fish assemblages of the Ohio River: Altered trophic and life history strategies with hydrologic alterations and land use modifications” --  in collaboration with Virginia Tech.

Changes correlated with a decrease in farmland and an increase in forests along the river. Modifications to the river’s hydrology from its 19 locks and dams contributed as well.

The improving environment led to more fish species feeding on plant matter and detritus, and fewer fish feeding on plankton and other fish, Pyron said.

He says the Ohio River Basin has changed dramatically since European settlers arrived in the late 1700s and early 1800s.

“The legacy of agriculture and land use is manifested in the Ohio River Basin, drastically modified via logging and wetland draining following European colonization,” Pyron said. “After this period, the Ohio River Basin watershed was historically dominated by agriculture, and then converted from agriculture to forest during the 1960s-80s. The effects of these changes on fish throughout the basin are not fully known.”

Factors that will affect fish species in the river into the future include land use modifications, climate change, and altered biotic interactions.