A very rare fish is dying in the Florida Keys. Scientists are struggling to find out why

A very rare fish is dying in the Florida Keys. Scientists are struggling to find out why

MIAMI — On a windy winter morning in January, Joyce Milelli was leading a kayak tour through the Lower Keys when the group rounded a mangrove island and encountered a startling sight: a rare, endangered sawfish, as big as Milelli’s paddleboard, wedged under a low clump of mangroves.

The discovery would set off alarms amid an ongoing mysterious fish disturbance, littering the scrubby islands between Key West and Big Pine with sick and dying fish.

“I knew right away something was not right,” said Milelli, a former nurse who grew up on Key Largo without ever seeing one of the rare sawfish. “I paddle all over the Lower Keys, all the way down to Dry Tortugas and the backcountry, where you don’t see many people paddling. My number one thing was to see a sawfish. So I knew this was really special, but why is it tucked under the branches?”

Five days later, the sawfish appeared again, this time flopping on a nearby shallow flat, where it quickly died.

A very rare fish is dying in the Florida Keys. Scientists are struggling to find out why

In the months since, about 60 sightings of endangered smalltooth sawfish have been reported, thrashing on beaches and flats, with images and video spreading across social media. At the Geiger Key Paddle Hut, where Milelli leads her tours, state wildlife officers this week hauled in a dead sawfish and wrapped it in a blue tarp.

Altogether, 20 of the very rare fish have been collected and examined by researchers, said Dean Grubbs, a Florida State University fish ecologist and member of the National Oceanic and Atmospheric Administration’s sawfish recovery team. But so far testing done by toxicology experts has gotten no closer to providing answers. And as numbers climb, concern grows.

“I do think we’re probably underestimating the number here in terms of figuring it out,” Grubbs said. “It’s puzzling to me, too, that there’d be so many sawfish compared to other species. It doesn’t make a lot of sense to me.”

Only five species of sawfish exist around the world, all at perilously low numbers. The smalltooth sawfish is the only sawfish found in U.S. waters and was added to the endangered species list in 2003 after it nearly vanished in the 1950s, wiped out by catch netting and loss of habitat in shallow estuaries where it gives birth to pups.

Grubbs and Florida researchers studying the fish have tagged over 100 to track their movements and found sawfish are typically found in deeper water, up to 200 feet deep, in January and February. (None of the dead fish found so far were tagged.) In March and April, they move north, near the Ten Thousand Islands, the Caloosahatchee River and Charlotte Harbor to give birth. Because tracking data is only uploaded twice a year, it’s not clear if their movements have changed this year.

And the unusual behavior observed in the Keys has never before been reported by sawfish experts, Grubbs said.

A very rare fish is dying in the Florida Keys. Scientists are struggling to find out why

“They should not be swimming in circles. They should not be coming that close to the shore. And certainly there’s no reason for their rostrum to be out of the water,” he said.

“I do think we’re probably underestimating the number here in terms of figuring it out. It’s puzzling … It doesn’t make a lot of sense to me.”

Dean Grubbs, a member of the National Oceanic and Atmospheric Administration’s sawfish recovery team.

Fish behaving strangely were first spotted in early November as far north as Biscayne Bay, when alarmed fishing guides began collecting reports and contacted the nonprofit Bonefish Tarpon Trust as sightings mounted in December.

By early January, the Lower Keys Fishing Guide Association and BTT had formed a working group and recruited two toxic algae experts from Florida Gulf Coast University and the University of South Alabama. The incidents mostly remained concentrated in near shore waters, along a nearly 25-mile stretch, from Summerland Key south to Sugarloaf, although Grubbs said sightings appear to be spreading.

“It’s very violent,” said Gregg Furstenwerth, a technical diver, who began spotting the fish in November. “You can see them doing gentle spinning after they’ve essentially, I guess, exhausted themselves. But when it first starts, it’s very, very violent.

Furstenwerth moved back to the scrubby islands between Big Pine and Key West, where he’d grown up, two years ago to introduce his wife to a playground of seagrass meadows and reefs teeming with fish, sponges and colorful coral that filled his childhood.

Instead, the couple has spent the fall and winter documenting the mysterious outbreak, filming pinfish, snook and jacks swirling and flopping.

Last week, he encountered a Goliath grouper, struggling to stay upright.

“It was scooping matter off the bottom as it was spinning and then spitting it out of its mouth repeatedly,” he said. “They seem to be unable to control themselves, to reach equilibrium. They can’t stay upright at all, like they’re just in all other directions except for upright.”

Word spreads, but officials remain tight-lipped

The worrisome behavior remained mostly under wraps. State agencies participating in the study group made no public announcements. But when endangered sawfish started turning up dead in late January, the ‘Conch Telegraph’ started buzzing.

Facebook lit up with pictures: sawfish swimming into the rocks at the White Street pier in Key West. A dead stingray on Higgs Beach. A Goliath grouper slamming its head into a muddy bottom.

“If something is going on, word spreads fast,” Milelli said. “If this continues, there’s a lot of fallout from this potentially.”

Neighbors began asking Fursternwerth what he knew.

“People are noticing. People who work at the gas station are telling me they know about it. They just heard about it in their local coffee shop,” he said. “Anybody who’s seen it is scared by it.”

The Florida Fish and Wildlife Conservation Commission has provided few details about the investigation. Requests for information from the National Oceanic and Atmospheric Administration and Monroe County were referred back to the FWC. When contacted by WLRN, FWC asked for a list of questions. But in response, the agency provided only confirmation of sawfish deaths, details about six sawfish, and no information about other sick fish.

Initially, FWC media staff released the number of reported sightings for the endangered fish as well as the number of bodies examined by scientists, but stopped.

Scientists say only reporting confirmed deaths likely underestimates the true count. In response to a records request last week, a clerk initially said the information had been processed but had been forwarded to Tallahassee for review before being released. A supervisor later said the request was still being processed.

Algae experts say pinning down the culprit is difficult. Initial water testing showed elevated levels of a tiny dinoflagellate found in the algae, called gambierdiscus, that causes ciguatera. The algae is naturally occurring and grows on reefs, where fish eat it, and typically doesn’t sicken fish. But humans who eat the fish can become very ill, suffering from nausea, vomiting and even neurologic symptoms.

When fish were tested, scientists found multiple toxins in addition to gambierdiscus, said Mike Parsons, an algae expert at Florida Gulf Coast University and a member of the state’s Blue Green Algae Task Force.

“We didn’t find a smoking gun. That doesn’t mean it’s not buried somewhere,” he said. “But it’s not as easy as some of us were hoping it would be.”

It’s possible that what’s making fish sick is a new affliction, or at least one never diagnosed by scientists, he said. The toxin produced by gambierdiscus was only identified last year, he said, and can change form after it enters a fish.

“Which means you have a moving target,” Parsons said. “So it just makes it really hard. Yeah, it’s really difficult.”

A resilient ecosystem under threat

It’s also possible that what’s ailing the fish is related to the unprecedented ocean heat wave that hit South Florida over the summer, drove up temperatures by about 5 degrees and bleached coral across the Keys.

“The system that’s impacted here in the Lower Keys is a very resilient ecosystem system that has endured a lot of change,” said Martin Grossell, a fish ecologist at the University of Miami Rosenstiel School who specializes in how fish work and the toxins that harm them.

But at some point, he said, mounting stresses like nutrient pollution from leaky septic tanks or other chemicals flushed into the sea from stormwater and ships, or rising ocean temperatures, start to trigger changes.

“We are adding to this environment and eventually may reach a threshold where now this balance is perturbed,” he said. “Then you start seeing things that you haven’t seen before and things that we have a hard time explaining.”

That’s left Keys residents to worry that time is running out.

“I tell people that the ocean doesn’t give up its secrets easily,” Furstenwerth said. “I was one year old when the (sea urchins) died, and they didn’t figure out what it was until this year,” he said, referring to the mass die-off of long-spined sea urchins that wiped out 98 percent in just 13 months in the 1980s.

“Is it going to take 41 years to figure I was doing this?” he said. “I don’t think it has 41 years.”

As the investigation continues, researchers are asking the public to report sightings of distressed fish to either the state fish kill hotline at 800-636-0511 or online at MyFWC.com/ReportFishKill. Sawfish sightings should be reported to 1-844-4SAWFISH via email to [email protected].

This story was produced in partnership with the Florida Climate Reporting Network, a multi-newsroom initiative founded by the Miami Herald, the South Florida Sun Sentinel, The Palm Beach Post, the Orlando Sentinel, WLRN Public Media and the Tampa Bay Times.