Report fish kills, even though they’re common this time of year
Tuesday, July 19, 2011
Media contact: Carli Segelson, 727-896-8626
High temperatures and cloudy, rainy days can spell trouble for
fish in Florida's marine and freshwater habitats. These conditions
can cause fish kills, which are natural occurrences that typically
do not cause permanent damage to the ecosystem or to fish
Nevertheless the Florida Fish and Wildlife Conservation
Commission (FWC) needs your help in keeping track of these
die-offs. FWC scientists record and monitor the location and extent
of fish kills in natural lakes and estuaries to see if there are
problems developing in an ecosystem that might require
investigation or restorative measures.
Many factors may contribute to a fish kill. Some fish kills are
complex and involve a variety of factors that may not be easily
discernable. However, most common causes of kills in brackish
estuaries, freshwater lakes and man-made retention ponds are well
understood by scientists.
Fish kills are commonly caused by weather-related factors.
Sudden temperature fluctuations or extreme temperatures can result
in fish kills any time of the year. Hot weather during the summer
months can cause fish kills because warm water holds less oxygen
than cold water. In addition, a lack of rain during hot-weather
months lowers the water levels in the system, allowing the water to
heat even more, which further depletes oxygen levels.
Fish kills also can occur during extended periods with little
sunshine. The process leading to these types of die-offs begins
with overcast skies and rainy weather. During extended periods of
overcast, rainy or cloudy weather, the biological system uses the
dissolved oxygen in the water faster than it can produce it.
Rain water can compound the situation by causing vegetation,
such as leaves and grass clippings, to wash into the system and
decompose. The decomposition process also can remove oxygen from
The good news is that most natural water bodies are resilient to
these types of fish kill events.
Residents can report fish kills in natural water bodies to the
FWC at MyFWC.com/FishKill
or by calling the FWC Fish Kill Hotline at 800-636-0511. It is not
necessary to report fish kills in man-made retention or private
ponds to the FWC.