Lake Santa Fe, a popular fishing spot for Alachua County anglers, is full of dead shad.
Thousands of threadfin shad, a bait fish only 1 to 2 inches long, were reported dead and floating on the surface of the lake Saturday, according to Florida Fish and Wildlife Conservation Commission Public Information Officer Karen Parker.
The suspected killer seems to be a combination of the summer heat and the cloudy, rainy days of the past week.
A deadly chain of events begins when water temperature is higher than normal, sometimes reaching 90-degrees Fahrenheit. Water that reaches such high temperatures cannot hold as much oxygen as cooler water, creating higher competition among organisms living near the surface.
The recent cloudy skies also make it difficult for plants in lakes to photosynthesize, decreasing the oxygen content in the water.
And if the clouds cut off sunlight for a few days, primary oxygen producers such as algae will die and begin to decompose, which uses even more oxygen.
These conditions are the "classic setup" for a low dissolved oxygen kill, and threadfin shad are among the first species to be affected, according to North Central Region Fisheries Administrator Allen Martin.
Jill McGuire, president of the Santa Fe Lake Dwellers Association Inc., an environmental watch organization, said Florida Lakewatch, part of UF's Institute of Food and Agricultural Sciences, tested the lake's water and found nothing abnormal.
"We're feeling a lot better," she said. "We were pretty nervous Friday."
McGuire said there are millions of threadfin shad in Santa Fe Lake, and that because they are small and sensitive to heat changes, they are the first to die when the temperature changes quickly or when oxygen is low.
"Hopefully it hasn't damaged the total population," McGuire said. "I think that's doubtful, as many as they are."
Parker, from the FWC, said that quick die-offs of fish populations are normal and aren't a cause for concern. Parker said the biggest concern now is the rancid smell from the rotting fish.
"It's not a pretty sight," she said.
But anglers who enjoy Lake Santa Fe have seen kills like this before. Robin Chiappini, owner of Chiappini's Bait & Tackle in Melrose, isn't concerned about any lasting effect on the fishing.
"The fishing is still really good, and the shad should spring right back," Chiappini said.
