(Orleans)– Extremely high water temperatures this summer on the Iowa Great Lakes are raising concern. Mike Hawkins is the Northwest Regional Fisheries Management Supervisor for the Iowa Department of Natural Resources. He says the extremely warm water is likely a contributing factor in some fish kills that are taking place. One of those is on the west side of Big Spirit Lake…
“It looks like, as you reported earlier, we have some gizzard shad showing up in higher abundance, numbers. Most of the fish in Templar Lagoon that are dead are those gizzard shad, they are very small. That could be disease related because they had such a large spawn and Mother Nature kind of putting that population back in check. But there’s also a very heavy blue-green die-off going on in the lagoon itself and that can take oxygen out of the water and cause a fish kill. In extreme events that definitely can occur.”
Hawkins says the water temperatures this summer on the Iowa Great Lakes are unprecedented…
“We had surface water temperatures well over 80 degrees. That puts a lot of stress on fish, and you may not get a fish kill occurring right then, but as that water temperature slowly cools down those fish continue to have stress and eventually can succumb to that. Yellow perch, northern pike, walleye in our area are more susceptible to those warm temperatures. They’re a cool water fish species and so when the water temperatures get that warm it puts a lot of stress on them and we could see some delayed mortalities as the rest of August rolls on here, so. Hoping definitely for some cooler temperatures, cooler air temperatures, to take some of the stress off these fish.”
Hawkins adds they are unsure if the high water temperatures this summer have actually set a record…
“That’s a good question. I don’t know if we have great information, historic information, that we can get at readily for water temps. But that would definitely be something to take a look at. In my recollection I don’t remember seeing surface water temperatures as warm as they were this summer. We had water temperatures getting into the mid 80’s. We had one day with one of our work boats on the water where the surface water temperature on Big Spirit was over 87 degrees. That’s incredibly warm, especially when some of the cool water species start to get very, very stressed at about 80 degrees.”
Hawkins made the comments late last week in an interview with KUOO news.
