Harsh winter weather may have caused local fish to die off

As the weather slowly starts to thaw out after one of the most brutal winters on record, the full effects of the harsh temperatures will start to show.

According to the News Tribune, the Missouri Department of Conservation (MDC) has been fielding dozens of calls about dead fish floating in thawing ponds and lakes. It's called a winter fish kill.

"We are getting dozens of reports of significant winter fish kills from all over the state," MDC resource scientist Rebecca O'Hearn told the paper, "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."

O'Hearn added that there is no cause for alarm -- the fish kills are just a natural side effect of a deep winter freeze. Once lakes and ponds freeze over, snow often accumulates, depriving the water of sunlight and oxygen.

"The plants weren't able to get the sunlight, so the decomposing plants that were in the bottom of the water will take away the oxygen," Indiana conservation officer Matt Tholen told CBS News. "The fish need the oxygen in the water, and that's what creates a fish kill, a lack of oxygen."

The fish kills take their toll on shallow, stocked ponds first. In larger ponds and lakes, bigger fish are affected first. "What we'll probably start seeing in the smaller bodies of water is probably the bass will start floating to the surface first," said Tholen.

A fisherman in Tippecanoe County, Indiana, tells CBS News that the bitter cold has likely spoiled some of the areas best fishing spots.

"If I go up to a little pond or lake or something and see a bunch of fish floating or dead on the banks, I probably wouldn't even waste my time," Moore said.

These fishing holes might not be lost forever, though. According to an informational sheet posted by the state government of Connecticut, enough fish generally survive to repopulate the area. The kills can even be beneficial, it says, because they reduce overpopulation.

There is little that can be done to avoid the fish kills. People have tried drilling holes in the ice to get oxygen circling, but it is a futile effort to attempt to compete with Mother Nature, said Tholen.

"This is natural. It does happen," he said. But he still encourages calling a local conservation office if a pond turns up dozens of dead fish, so that trained authorities can verify that the weather was the only culprit.

"If you do see a fish kill we would still like to know about it, because it could be the winter fish kill, but it might be something else that's affecting these fish," said Tholen.