Dead invasive carp spotted recently along the Ohio River in Daviess and Hancock counties were likely victims of low dissolved oxygen levels, according to the Kentucky Department of Fish and Wildlife Resources.
The fish were found in the Cannelton Pool last week and have since extended downriver to the Owensboro riverfront. Fisheries Program Coordinator Jeffrey Herod said these occurrences are not unusual for this time of year, and similar events have been reported in previous summers.
“The most likely cause of these fish mortalities is low dissolved oxygen,” Herod said. “Low dissolved oxygen is likely to happen because of high water temperatures, sunny days, and increased oxygen demand by many aquatic organisms.”
During summer nights, not only fish but also plants, bacteria, and algae consume oxygen in the water, he said. He added that because warm water holds less oxygen than cooler water, levels can drop drastically overnight, leaving sensitive species — including invasive carp — vulnerable.
Herod noted the die-offs are more noticeable with carp because the species is abundant and tends to be larger in size. Other possible causes include injuries from passing through dam spill gates or gas bubble disease, both of which are associated with dam water discharge.
Fish and Wildlife officials encouraged residents to continue reporting unusual wildlife activity. More information about fish die-offs, invasive carp, and aquatic nuisance species is available at fw.ky.gov.
