Friday, December 10, 2010

Cold Weather May Lead to Fish Kills

Remember last January when there was a long cold spell in our region? During that time there were a lot of fish kills because of the prolonged cold weather. Well, now that we are experiencing that cold weather again, there could be the chance of fish kills in our local waters. Even though there may be more fish kills because of the colder than normal weather there is no cause for alarm or concern. These are natural occurrences and generally do not cause permanent damage to the ecosystem or to fish populations. It actually could be beneficial in that it helps to limit the spread of invasive, exotic species.
Fish kills are often caused by sudden temperature changes or by extended periods of extreme temperatures. This can occur anytime of year in Florida but most commonly occurs in the winter when the air temperature drops. Even though the water does stay relatively warm after the air cools, if there is an extended period of cold this can cause the water temperatures in inland waters and estuaries to drop. The fish may be killed outright by cold stress or the cold may just weaken them so they are more susceptible to disease. Warm-water species, including snook (native) and tilapia (exotic) are particularly vulnerable to cold temperatures.
Fish affected by the cold may appear lethargic and may be seen at the surface where the water may be warmer from the sun. All recreational regulations still apply to fish impacted by the cold temperatures, even if they appear to be dead or dying. It's important for Florida Fish and Wildlife Conservation Commission (FWC) scientists to keep track of the location and extent of fish kills in natural water bodies in order to determine if there are problems developing in the ecosystem that might require further investigation. Although it is not necessary to report fish kills in private ponds, FWC scientists can assist the public by providing information about cold-weather fish kills in these ponds.
The public can report fish kills in natural water bodies (lakes, estuaries, rivers) to the FWC at or call the FWC Fish Kill Hotline at 800-636-0511. For more information on fish kills, visit and select "Fish and Wildlife Health" under the "Explore" section.