(Lewis) The Iowa DNR is starting to field calls about summer fish kill.
Fisheries Biologist Bryan Hayes says hot, dry weather followed by some cloudy days provides a dangerous mix in smaller ponds. “The heat just warms the water up and reduces the water’s capacity to hold oxygen. The warmer the water is the less oxygen you have to work with. When you have water temperatures in the mid-80’s you aren’t working with much dissolved oxygen in the water and the fish rely on that to stay alive.”
An algae bloom can often be the first sign of trouble. “You have an algae bloom followed by a sudden die off of that algae. Dead algae decays in the pond and that process depletes the oxygen. If your pond goes from a green color to a brown color that’s an indication that algae has died and that puts a demand on the oxygen which puts your fish at risk.”
Hayes says summer kill events are often times not complete. Some fish will survive, but typically the biggest fish are the most susceptible to low dissolved oxygen levels.
