Hundreds of sharks flee into Florida canals to escape toxic red tide

Red tide has reportedly led to the deaths of more than 600 tonnes of marine life in Florida in 2021.

A dangerous algal bloom off Florida's Gulf Coast has caused quite a scare for sharks in the region, as hundreds of them fled to inland canals recently to escape its deadly effects.

Red tide, a harmful algal bloom, occurs nearly every summer along Florida’s Gulf Coast, according to NOAA. Reflective of its name, the bloom frequently turns the water red. It can also cause respiratory problems for humans.

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Multiple shark species, including bonnethead, blacktip, nurse and lemon, have been seen skirting through Longboat Key and in the canals of Buttonwood Harbour recently, distanced from their typical habitat, to avoid the bloom. The sharks usually reside in Tampa Bay, Sarasota Bay and along the coast from Pasco to Sarasota County.

The number of sharks that have appeared in the canals have taken some local residents by surprise.

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“You literally could have walked across the canal on the backs of sharks — that’s how many there were,” Janelle Branower, who lives in Longboat Key, told WFLA-TV.

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Another local citizen, John Wagman, told WFLA 8 -- "You first saw the wings, they were just popping up. Just something I had never seen before in a canal."

Red tide has reportedly led to the deaths of more than 600 tonnes of marine life in Florida in 2021. The bloom is the result of a microscopic algae that produces toxins that kill fish and makes shellfish unsafe to eat, NOAA says.


The Mote Marine Laboratory and Aquarium says the bloom has been "patchy and persistent since December 2020," and has recently increased in severity where the sharks usually reside in Florida.

The Florida Red Tide Mitigation and Technology Development Initiative revolves around developing tools and technologies to mitigate red tide and decrease the impacts on the environment and economy and quality of life in Florida.

"Florida red tides are caused by the overabundance of cells of native species of algae, Karenia brevis. Clay mitigation involves spraying the surface of the water with a slurry of modified clay particles and seawater, and as the dense clay particles sink, they combine with red tide cells. This process can kill the cells and also bury them in the sediment on the seafloor," Mote Marine Laboratory and Aquarium said in the news release.

Larry Brand, a professor at the University of Miami Rosenstiel School of Marine and Atmospheric Science, said red tide in Florida is "getting much worse," attributing most of it to land-based toxins such as agricultural runoff and fertilizer runoff from lawns.

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It was reported by the Florida Fish and Wildlife Commission (FFWC) last week that massive fish kills occurred in nine west Florida counties.

Thumbnail courtesy of NOAA.

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