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High Concentrations Of Red Tide Causing Fish Kills in Sarasota County

Turtle conservationists have seen seven dead Kemp's ridley sea turtles and one dead loggerhead.
Mote Marine Laboratory
The Florida Channel
Leon County Judge John Cooper on June 30, 2022, in a screen grab from The Florida Channel.

Red tide is getting worse in the Tampa Bay area, causing fish kills last week in parts of Sarasota County.

The Florida Fish and Wildlife Conservation Commission collected water samples from Sarasota County  this week and found high levels of the red tide organism, Karenia brevis.

Though red tide wasn't found in all areas of Sarasota County, very low to high concentrations of the organism were found in several areas off the shore.  Scientists also found very low concentrations of red tide off Clearwater Beach.

Red tide was first detected off Sarasota County last week in medium concentrations. Fish kills were reported this week in Venice and Englewood.

Michelle Kerr, a spokesperson for FWC, says that the organism is natural to the Gulf of Mexico, but it can multiply uncontrollably, and that’s when it becomes dangerous.

“Karenia brevis is a microscopic algae that occurs naturally in the Gulf of Mexico,” Kerr explained. “Red tide is a harmful algal bloom which starts offshore in the Gulf of Mexico, about 20 to 30 miles offshore and travels inshore by winds and currents.”

Though very low levels of the organism are not dangerous, health officials will stop the harvesting of shellfish like scallops and oysters once levels become elevated.

“You'll start to see some shellfish closures in general due to red tide because shellfish are bivalves, and they actually are filter feeders,” Kerr said. “They're filtering out those toxins from the water and those can accumulate in the shellfish system.”

Highly concentrated amounts of Karenia brevis make shellfish unsafe to eat.

High levels of the organism can change the water’s color and cause respiratory irritation in people and animals. Health officials recommend reducing exposure to the toxin by limiting time spent on the beach.

“If you are at the beach with your pets, don’t allow pets to play with dead fish or in water that has high concentrations of red tide,” Kerr said.

FWC scientists constantly testing red tide levels in the Gulf of Mexico and post results daily on its website

The organization also asks the public for help identifying effects of the bloom.

“It's very important for the public to report any fish kills because they provide valuable information and help scientists track the impacts of the bloom,” Kerr said.

Since the start of the month, 10 fish kills have been reported to FWC in Pinellas, Manatee, Sarasota and Charlotte counties.

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Erin O’Brien is a WUSF/USF Zimmerman School digital news intern for summer 2019.