Why Are FL Fish Spinning In Circles To Their Death?

KEY WEST, FL — Scientists aren’t sure if it’s toxic algae blooms, climate change or some other mystery that is causing dozens of species of Florida fish to spin in tight circles until they beach themselves and die.

They appear disoriented and confused, swim with their heads out of the water at times, alternatively bob and sink, and show symptoms of equilibrium issues that researchers theorize could be causing them to lose their balance and swim on their sides or upside down.

The mysterious behavior was first observed late last year along a 35-mile stretch in the lower Keys. As of this month, the behavior has been reported in 44 species of fish in waters as far north as Miami, National Geographic reported. Although the Florida Fish and Wildlife Conservation Commission hasn’t taken an official count, many of the fish are washing up dead, the publication reported.

Scuba diver Gregg Furstenwerth told Miami ABC affiliate WSVN that when he saw a distressed pinfish spinning in a seagrass meadow in the Florida Keys last November, he “thought it was hilarious.”

He soon saw the fish were in serious trouble. Conversations with other divers revealed they, too, had seen the bizarre behavior.

“It’s alarming and sad and depressing,” he told the TV station. “Just beyond anything I’ve ever seen in my life. And I’ve been in the water a lot.”

Among the species displaying the spinning phenomenon are species of rays and sharks, Goliath grouper, tarpon, snook, mullet, gray snapper, ballyhoo, pinfish, sand perch, needlefish, pilchards, grunts, blue runners and the critically endangered smalltooth sawfish.

Most recently, Furstenwerth saw a squid swimming in circles, adding another species to the growing list.

‘The Scariest Thing’

Mary McCauley, who lives in Cudjoe Bay, shared video with Fort Myers ABC affiliate WZVN after she saw a sawfish “come out of the water” and go after her dog, before flopping onto the beach.

“It was the scariest thing because of that saw, it just came out of nowhere,” she told the outlet, explaining the sawfish appeared sick and disoriented as it lingered on the beach, “like there was something wrong with [its] brains.”

McCauley, whose back yard has access to the beach, said she has seen the same behavior in a sting ray. “It was about 6 feet wide, and it was just flopping around on my beach [and] the next beach over,” she told the TV station. “It was acting very strange.”

A video posted on Instagram by fisherman Angel Eiras shows dozens of snook behaving unusually and dead fish along the shore in the Florida Keys.

‘Mass Mortality Events’

Flummoxed researchers are racing to find out what’s causing the bizarre behavior before more fish die.

Likely culprits — including red tide, which occurs when algae blooms out of control, or low oxygen levels in the water — have been ruled out in a collaborative investigation by various universities, institutes and state agencies.

The investigation is currently focused on a microscopic algae in the genus Gambierdiscus, which produces ciguatoxins. The toxin is naturally occurring but usually harmless. But in high levels, they can cause an illness known as ciguatera, whose symptoms include vomiting, nausea and neurological symptoms.

Water samples collected from the Big Pines Key area, where spinning fish were observed, showed about 1,000 Gambierdiscus cells per liter of water — far above the normal range of around 30 to 40 cells per liter. Some of the dead fish contained ciguatoxins. Others contained okadaic acid, caused by another bottom-dwelling seaweed.

In earlier experiments, fish given food with ciguatoxins displayed neurological symptoms that included hyperactivity and twitching, giving scientists something to go on as they tackled the question — why are Florida fish acting funny? — that has been trending on social media.

In one test of the working hypothesis, laboratory fish are exposed to water collected from Big Pine Key waters, where spinning fish have been observed. In another experiment, researchers are exposing fish to toxin added to artificial seawater at levels equal to those found in the Keys.

A team from the nonprofit Ocean First Institute is also contributing to the research, comparing blood samples from sharks taken before the spinning phenomenon reports and after to determine is the long-term health of shark species that have exhibited the mysterious condition.

There is also some evidence that climate-driven warming is expanding the range of Gambierdiscus into higher latitude U.S. waters. Over the past couple of decades, the genus has been documented in North Carolina.

Researchers say the toxin thrives in areas that are environmentally stressed. The Florida Keys already face myriad environmental problems, including coral reef bleaching associated with warming waters, water pollution and development pressures.

Ocean First Institute said “spinning fish disease” reported in various species of fish and sharks in the Florida Keys “is leading to mass mortality events,” a “big blow to the already impacted Florida Keys.”

“One interesting thing about this is so many different fishes are being affected,” Mike Parsons, a marine science professor at Florida Gulf Coast University, told WSVN. “So that led to our hypothesis that maybe it’s something in the water, maybe dissolved in the water.”

‘I Don’t Think We Have Any Clue Yet’

Of special interest to researchers is how the mystery illness could affect the critically endangered smalltooth sawfish.

At least 21 sawfish have washed up dead, and 60 more reports have been taken of “distressed” sawfish, One of the sick fish was discovered at Boynton Beach, more than 200 miles north of the Keys in Palm Beach County.

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Sawfish, which can reach lengths of up to 12 feet, were once abundant, but only two populations remain — one off the Florida coast and another smaller population in the Bahamas.

“That means the recovery of the species is pretty much dependent on the U.S. population,” Dean Grubbs, a fish ecologist at Florida State University, told National Geographic.

Alison Robertson, a marine scientist who studies harmful algal blooms at the University of South Alabama's Stokes School of Marine and Environmental Sciences and the Dauphin Island Sea Lab, told National Geographic “it’s strange to see such a prolonged event affecting so many species.”

“Everybody wants to know what it is right now,” Robertson said. “We’re going to do everything we possibly can to work together to try and identify that so we can come up with solutions.”

Grubbs said researchers don’t know if the fish kill is a one-event or something that will collapse populations of certain fish that are already in trouble.

“I don’t think we have any clue yet whether this is something that will be over in a year, and we won't even know it happened, or [if it’s] potentially catastrophic,” he told National Geographic. “My hope for spreading the word is just that it gets out to more brain power.”