Officials from the Illinois Department of Natural Resources [IDNR] said they are monitoring an extensive die-off of silver carp in the Peoria pool of the Illinois River, stretching between Peoria and Henry.
Deceased fish have been flowing downstream, releasing an unpleasant odor near affected areas.
Biologists for IDNR fisheries believe the incident is naturally occurring as a result of spawning stress and water chemistry changes brought on by recent rain.
“These environmental cues trigger spawning activity, often resulting in large numbers of fish moving and spawning at the same time,” IDNR fisheries chief Michael McClelland said in a media release.
“Spawning requires a significant amount of energy and can place considerable physiological stress on fish.”
There is no evidence of chemical contamination or pollution and no indication of any ongoing water quality problem. The foul smell is expected to diminish gradually as river conditions improve.
Silver carp are an invasive species found in Illinois waterways that typically spawns during periods of rising river levels and increasing water temperatures, which Central Illinois has experienced recently.
The IDNR said it’s uncertain how many silver carp died because of the occurrence. No native fish species or other aquatic organisms have been affected.
