Thursday, January 21, 2010

Recent Fish Kills

From email in response to reported fish kill at Camp Bayou:

The cold weather patterns we experienced across the state have resulted in widespread fish kills, both in fresh and salt water. There are a few reasons why cold temperatures affected fish in such a negative manner:

• Warm water fish such as snook are more susceptible to cold. Optimum temperatures for warm water fish ranges between 24 and 30 degrees C. The initial shock can kill some species outright or they can succumb to the cold after extended periods.
• Sometimes fish may survive, but the cold stress can make them more susceptible to disease.
• Some of our initial reports described fish gasping for air at the surface. In lakes and canals, when the water at the surface is chilled, the oxygen rich water on the surface can drop and mix with the warmer, oxygen poor water and low dissolved conditions can develop, suffocating the fish.
• Fish affected by the cold may appear lethargic and may be seen at the surface where the water may be warmer from the sun.

You will perhaps continue to see fish gasping for air, or fish that appear to be diseased floating to the surface. Please be advised that:
• The fish were under extreme cold stress for 14 days, slowing down their metabolism. Additionally, fish stop eating when the water is too cold.
• Fish that died during the cold snap, in relatively good condition, are now decomposing with the warmer temperatures and floating to the surface, so the carcasses appear to be freshly dead, but they have been dead for several days.
• Due to the decomposing carcasses, water quality may be low, causing dissolved oxygen levels to decrease, resulting in further stress to the fish.

Fish Clean-up:
• The FWC does not clean up fish.
• The function of the Fish Kill Hotline is to monitor fish kills and disease around the state.
• Law Enforcement Officers will use discretion when encountering individuals removing and possessing dead fish that may be prohibited because of size or season from the water or shoreline if those fish are possessed because of an effort to remove a public nuisance. However, if circumstances lead the Officer to believe that fish are being kept for consumption or purpose other than removal of a nuisance, criminal charges may be applicable.
• If you witness illegal activity regarding poaching or other illegal activity, call FWC’s Wildlife Alert (800-404-3922) immediately.
• For human health concerns, please contact your local county Department of Health.

Informational papers:
Dissolved Oxygen for Fish
Understanding Fish Kills in Florida Freshwater Systems

FWC has prepared several press releases that are now available at our web site

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