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FWC Determines Fungus Caused St. Johns Fish Kill

by the Fish Site Editor
18 November 2010, at 12:00am

US - Biologists with the Florida Fish and Wildlife Conservation Commission's (FWC) Fish and Wildlife Research Institute have determined the cause of a recent fish kill in the St. Johns River. Testing confirmed that a fungus led to the fish die-off that occurred in the river in mid-October.

The FWC received reports of dead fish and fish with ulcers from October 20th onwards. Reports came from an area of the river just south of Interstate 95 near Jacksonville and as far south as Green Cove Springs. The FWC responded by analyzing dead fish and water samples from the area.

FWC biologists suspected that a fungus called "Aphanomyces invadans" caused an infection, which produced ulcer-like lesions and the eventual death of shad, mullet and menhaden in the St. Johns River. The National Oceanic and Atmospheric Administration confirmed the FWC's findings when it conducted specialized testing on diseased-fish samples provided by the FWC.

This fungus, which is a type of water mold, occurs naturally in estuaries and freshwater systems in Florida - generally in water bodies with lower salinity levels. Scientists have confirmed that it causes an ulcer-forming disease in estuarine and freshwater fish worldwide. This is not the first time that fish with these types of ulcers have been observed in the St. Johns River. Reports of similar incidents date back to the late 1970s. However, biologists have no evidence that there is a connection between this fish kill and the large-scale fish kill that occurred in the river earlier this summer.

FWC scientists track the location and extent of fish kills in natural water bodies. This enables them to monitor the development of serious problems in an ecosystem that might require investigation or restoration measures.

the Fish Site Editor