It remains unclear why hundreds of dead fish floated to the surface of Lake Apopka two weeks ago, state wildlife officials say.
Testing remains ongoing. No evidence points to an algal bloom or low dissolved oxygen levels in the water as the likely cause, according to the Florida Fish and Wildlife Conservation Commission, which reports it also received 31 reports of fish kills on the lakle between Jan. 31 and Feb. 11.
Cold temperatures can also trigger fish kills, especially if water temperatures drop suddenly or last for an extended period of time, the agency says. Other common causes include disease, herbicide, and spills of sewage or petroleum.
Orange County resident Andy Braddock calls Lake Apopka, Florida’s fourth-largest lake, his “happy place.” Braddock says he spends lots of time fishing on the lake and captured video of the fish kill after recently discovering the event while boating.
Like most lakes in Central Florida, Lake Apopka is polluted enough for state and federal agencies to consider it “impaired.” Restoration efforts over the years have led to some improvements, but the lake is still impaired by pollution from nutrients, like nitrogen and phosphorus, as well as pesticides, according to the Florida Department of Environmental Protection.
Some area residents, including fishing enthusiasts who frequent the lake, are concerned the state’s herbicide strategy for aquatic plant management may be too aggressive. Herbicides are used to control the spread of invasive aquatic plants, like hydrilla, but some worry the chemicals in those herbicides may do more harm than good, particularly to fish and other wildlife.
FWC is not currently applying herbicide to Lake Apopka, according to agency data, but did apply herbicide to treat hydrilla there in 2023.
Some fish that washed onto Lake Apopka’s south shore at the Oakland Nature Preserve are still decomposing, according to Nicole O’Brien, the preserve’s managing director. But no more dead fish appear to be rising to the surface.
“It seems like the active event is over,” O’Brien said.
State environmental officials continue to analyze water samples that FWC collected during the fish kill. The St. Johns River Water Management District also collected water samples, per an FWC spokesperson.
Staff with FWC also collected dead fish for analysis, but those necropsies haven’t yielded conclusive results.
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