21-03-2025
- Science
- National Geographic
Fish are spinning to death in the Florida Keys—again. Why is history repeating?
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Now, fish are spinning again, though in smaller numbers and happening in a much smaller geographic area, according to the Florida Fish and Wildlife Conservation Commission (FWC). One question is whether these fish are experiencing new symptoms or if they're still suffering from last year's exposure. What's perplexing is that algae levels in the water are relatively low, unlike during the 2023-2024 event, says Matthews.
Since December 2024, FWC has received 44 reports of fish exhibiting spinning behavior, adding to more than 500 related reports since December 2023. Among these new reports, 22 have involved sawfish, including six confirmed deaths, with another likely occurring on March 20, according to Matthews. 'There's a sawfish 200 yards from me on the shoreline right now that we've got a team taking blood from to figure out what's going on,' he said. 'It's so sad, these are amazing animals.'
(Here's how scientists are trying to save the last sawfish stronghold.)
What we know about the toxins
Mike Parsons, a researcher from Florida Gulf Coast University, has been regularly sampling water for algae species suspected to be behind the toxins. One algae genus, Gambierdiscus, has been flagged as a possible toxin source, though the exact species hasn't been identified and doesn't match known species.
To definitively link the Gambierdiscus species to the events, scientists are working to identify the chemical makeup of the toxin, or toxins, at play too. 'You can't see it in the water, so it's a lot harder for us to track it down,' Matthews says, meaning they need to collect samples when the fish are still actively spinning. Researchers have found Gambierdiscus algae on the gills of the fish, and water and fish tissue tests found evidence of neurotoxins. 'We just really want to connect that smoking gun,' says Matthews.
