ALTON/ST. CHARLES COUNTY — Dead carp have been reported recently near the Melvin Price Lock and Dam area in Alton, along the Great River Road near the city and in the Mississippi River in Pike, Lincoln and St. Charles counties, where state wildlife officials said warm temperatures and low oxygen in shallow water are primarily causing mass fish deaths, not a chemical spill.
The photo above was taken this week and shows dead carp floating in the Mississippi River along the Great River Road. The Missouri Department of Conservation checked into the dead carp and said the conditions have been especially hard on invasive silver and bighead carp.
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The department said heat warms the water, while lower water levels leave less oxygen than cooler water would hold. It said the invasive carp tend to school together in shallow waters with very little oxygen.
The majority of the dead fish have been described as invasive carp unable to cope with recent warm temperatures around the region, the Missouri Department of Conservation said.
“Ninety percent of them are these invasive silver and bighead carp,” the Missouri Department of Conservation said in a statement. “They’re an invasive species that people will have complaints of them jumping on their boats. So, actually, this isn’t a bad thing. Our native species have lived in these waters for generations.”
The Missouri Department of Natural Resources said intense summer heat warms river water and decreases available dissolved oxygen. Lower seasonal river stages also create shallow, slow-moving backwaters and isolated pockets where fish gather together.
State agencies said invasive carp species are more vulnerable to the conditions than native fish populations. They view the die-off as a natural culling of an unwanted invasive species rather than a threat to native sportfish or ecosystem health.
Birds and wildlife will feed on the dead carp as they float downstream and wind up along the shoreline, the Missouri Department of Conservation said.
The Missouri Department of Conservation, working alongside partner environmental groups, monitors the seasonal events. Officials said there is no need to report routine floating carp during this heat-driven regional event, though reports of other unusual pollution or distinct fish kills are still welcomed through the MDC Fish Kills Information page.
