Fish kills could increase from warming waterways
Because water temperatures are heating up, anglers may notice more dead fish than usual on their favorite waterbodies. Many underlying causes can explain this uptick in fish die-offs during warm weather periods, from pathogens such as bacteria, viruses, fungi and parasites, to environmental issues, like low dissolved oxygen levels and thermal stress.
Anglers and boaters are reminded to report fish kill events to their local fish biologist. It is important to note any fish kill needs to be thoroughly investigated through coordinated efforts between biologists and fish health staff, to confirm the underlying cause.
Since dead fish decay quickly in warm temperatures and water conditions can change rapidly, it won’t always be possible to definitively determine the reason for a fish kill.
Though anglers and boaters may see high numbers of dead or diseased fish as waters warm, know that these events usually do not have a lasting impact on the larger fish population.
Anglers and their pets should never consume dead, or visibly sick, fish. Thoroughly cook any harvested fish, and follow the U.S. Food and Drug Administration’s food safety guidelines.
If catching a diseased or dying fish, or observing a fish kill, take the following steps:
• Always wear gloves, or wash hands after handling dead or dying fish.
• Anglers should not actively collect fish samples from a fish kill event. If accidentally catching a diseased or dying fish, retain the fish as a part of the daily bag limit and place the fish in a plastic bag on ice in a cooler. Do not transport the fish to a DNR office or hatchery.
• Note the waterbody, date, fish species, and number of dead or dying fish, and report it immediately to a local fisheries biologist or the DNR tip line, at 800-847-9367.
• If possible, and it’s safe to do so, take clear images of the affected area (i.e. waterbody showing dead/dying fish) and close-up images of the affected fish.
A local biologist will be in contact as soon as they are able, and will determine whether the carcass can be collected or how it should be properly disposed of. Note that because of resources, the DNR staff will not be able to visit every potentially diseased caught fish or occurrence of dead fish.
