Cold winter takes toll on fish

Photo used under a Creative Commons license courtesy Hans Hillewaert.

Photo used under a Creative Commons license courtesy Hans Hillewaert.

This Missouri winter has been the coldest in 35 years, cold enough to cause the popping noise of “frost quakes,” cold enough to kill fish.

The Missouri Department of Conservation warns people not to panic as melting ice reveals many dead fish.

“It’s not like we have a mass contamination or anything,” said Bob Mattucks, fisheries management biologist. “Ninety-nine percent of the time dead fish are due to Mother Nature.”

MDC reports in a press release that people all over the state are reporting dead fish and concerns about what killed them.

They are dying in ponds, in big lakes and reservoirs and many more will show up as more ice melts.

Blame it on the cold. From Dec. 1 to Feb. 28 was the coldest since the winter of 1978-79 and the ninth coldest on record.

The cold reduced water temperatures and caused abnormally thick and widespread ice. Then deep snow prevented light from reaching aquatic plants, and they began to die.

“…and when they die, they not only are not releasing oxygen into the water, their decomposition actually consumes oxygen,” said Rebecca O’Hearn, MDC resource scientist.

“If that goes on for long enough, like it has this year, fish can suffocate,” she said.

Cold temperature alone can also kill fish, which normally go into winter with just enough fat reserves to survive. Small fish are more vulnerable to this and that is why there have been large die-offs of shad.

As bad as the fish kills are, they seldom have a serious and long-term effect on fish populations, officials said.

People who see fish kills should report them to the nearest conservation department office, they said, to help officials evaluate the losses. If pollution is suspected of killing fish or wildlife, call the Missouri Department of Natural Resources Environmental Emergency Response Line at 573-634-2436.

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