After tireless months of data collection and testing, scientists have likely pinpointed the cause of the spinning and dying fish in Florida: a combina

We finally know what caused Florida fish to spin in circles until they died

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2025-01-02 06:00:07

After tireless months of data collection and testing, scientists have likely pinpointed the cause of the spinning and dying fish in Florida: a combination of toxic algae.

In November 2023, Florida Keys residents began observing fish and rays—including the critically endangered smalltooth sawfish—whirling in circles, usually until they died. Scientists later recorded the phenomenon in more than 80 species, including parrotfish, bull sharks, and goliath grouper.

This prompted a collaborative investigation between governmental agencies, nonprofits, universities, and more to figure out the culprit before it could set back decades of conservation efforts for the sawfish.

At least 54 of these unique rays, which sport tooth-studded saws, or rostrums, are confirmed dead—though many more likely also succumbed to the toxins, experts say. There are only around 650 breeding sawfish females in Florida.

After testing hundreds of water and fish samples, the experts concluded the symptomatic fish died from combined exposure to multiple toxins, possibly originating from multiple species of dinoflagellates, a type of microscopic algae.