Fish kills aren’t pretty to look at, but scientists say they’re normal occurrences during the winter time.
When lakes freeze over and get dusted with snow, little light makes its way to the aquatic vegetation below. From there, it’s just a matter of time before some of the plants die off.
During decline, the vegetation produces less and less oxygen, adding to the low oxygen conditions that affect fish and other organisms. When the plants die, their decomposition also takes oxygen out of the water.
According to Rebecca O’Hearn, a resource scientist with the Missouri Department of Conservation:
“We are getting dozens of reports of significant winter fish kills from all over the state, from places with shallow water, such as Eagle Bluffs Conservation Area, and from huge water bodies such as Truman and Table Rock lakes, Lake of the Ozarks, and Pomme de Terre and Stockton reservoirs.”
These fish kills, often called “winterkills,” aren’t strange, but the frequency at which they’ve been seen recently is uncommon. The cold, prolonged temperatures of the 2014 winter are to blame. As the Minnesota DNR relates: “Early ice-on and late ice-out dates also increase the winterkill potential.”
“Winterkill is the most common type of fish kill. Given the harsh conditions this winter with thick ice and deep snow cover, it will be particularly common in shallow lakes and streams and ponds. These kills are localized and typically do not affect the overall health of the fish populations or fishing quality.”
Deeper water bodies like the Great Lakes may be less affected by fish kills than shallower ones nearby. But with record Great Lakes ice cover adding up (sitting at its highest in 35 years), what can be expected in the spring?
The Associated Press reports: “Fish and other aquatic life typically die in late winter, but may not be noticed until a month after the ice melts because they’re temporarily preserved by the cold water.”
Video: Large fish kill expected in inland lakes because of harsh winter. (Credit: WZZM13 via wzzm13.com)