Anyone who finds fish die-offs, which are several or more dead fish found in a lake or stream, should report it to the Minnesota Department of Natural Resources. Early reporting can help the DNR to determine possible water quality or bacteria issues.
“We hope people will help us out by reporting dead fish right away so we can determine if an investigation is needed," said Tom Burri, limnology consultant with the DNR, in a news release.
This time of year, fish die-offs are usually caused by a common bacterial infection called columnaris. It affects fish as water temperatures warm and fish are stressed from spawning.
Fish diseases and infection are often confined to a fish of a specific species and size. Human activity tends to be the culprit in fish die-off incidents involving fish of different size and species, according to the release.
“People should try to describe the fish types and sizes they see when making a report. That kind of information helps immensely,” Burri said.
Human causes can be toxic chemical spills, pesticides or fertilizers, stormwater runoff, or water discharged at high temperatures.
Report fish die-off incidents by calling the state duty officer at 651-649-5451 or 800-422-0798. This provides a single point of contact for the incident, which is available at all times.