How high heat can lead to fish kills

Many people have had their hand at fishing, but an alarming sight that few have seen while fishing is large numbers of lifeless fish rising to the surface in high numbers. This site can be alarming during the late summer months and occurs due to longer stretches of extreme heat.

For about the past week, Mid-Missouri has seen heat index values up to triple digits and highs in the 90s.

This trend looks to continue with an additional stretch of ABC 17 storm track weather days being issued from Sunday through next Tuesday. And great chances of fish kills like those recently seen at Mark Twain Lake, where many dead walleye fish were observed at Great Barren, Spalding, and dam portions of the lake could occur more in local waterways.

An example of how fish kills occur can be shown with the container above. Notice the blue water at the bottom, that's going to be water that's not very oxygen rich. This is typically water fish do not do well in. Most of the oxygen rich water is going to be retained back near the surface level and just below.

Now during the summer months, whenever those temperatures really start to spike up in a heat wave , we'll start to see that oxygen-rich clear levels start to shrink like that observed in the picture just above.

If fish can't maintain the right temperature and get to that level, that can lead to a fish kill like what we've seen in the walleye recently. Temperatures into the second half of the week remain above average, which could raise more concerns for future fish kills. If you do see a suspected fish kill, make sure to report them to https://mdc12.mdc.mo.gov/applications/FishKillsIntake.