Fishing guides in the Florida Keys began reporting unusual sightings to Ross Boucek last fall. Small bait fish begin to move in tight circles in the water in pain, especially at night.
As the months went by, more reports trickled in to Dr. Bowsek, a biologist with the Bonefish and Tarpon Trust, a nonprofit conservation group. In the shallow waters of the Atlantic and Gulf of Mexico, larger fish, horse mackerel and snook were swimming in spirals and upside down. So were stingrays and the occasional shark.
Dr. Bowsek called scientists at state agencies and universities. They held meetings, took water and fish samples, and tried to figure out what was causing the fish's strange behavior. Parasite? Sewage spill? Any other contaminants?
Then, in January, the mysterious disease began attacking smalltooth sawfish, a species of large, prehistoric-looking rays. It gets its name from the appearance of its snout-like snout lined with sharp teeth. The endangered sawfish, which is only reliably present in southernmost Florida, has begun to die.
Dr Bowsek said the search for answers became urgent: “At that moment, endangered species began to go extinct at an unprecedented rate.”
He is currently donning a wetsuit, flippers and snorkeling mask to collect samples and record data from sensors he has placed along the ocean floor to identify changes and patterns that may help solve the mystery. I spend a lot of time looking for.
At least 38 sawfish have died so far this year, according to the Florida Fish and Wildlife Commission, which is investigating the deaths. R. Dean Grubbs, a fish ecologist at Florida State University, said there are probably only a few hundred female sawfish left breeding in the wild. The fish can grow up to 18 feet long, according to the commission.
A research team led by state scientists is rushing to conduct experiments, tag the sawfish and sample their blood. The Florida Legislature designated $2 million in emergency funding to support this work.
Some believe that last summer's record sea temperatures, which bleached coral throughout the Keys, may have altered the ecosystem and caused abnormal microalgae blooms.
The best results so far show that microalgae that naturally occur near the ocean floor produce high levels of toxins that have acute effects on the nervous systems of fish that swim into those waters.
Michael Parsons, a marine science professor at Florida Gulf Coast University, explains why spinning fish appear to recover when pulled from the ocean floor (where toxin concentrations are high) to the surface (where toxin concentrations are low). That might explain it, said Michael Parsons, a professor of marine science at Florida Gulf Coast University. Sawfish are fish that live on the ocean floor.
Since early April, the National Marine Fisheries Service has been working to rescue and rehabilitate the stranded sawfish, a logistically difficult effort that the agency calls the first of its kind in the United States. The team rescued the first sawfish, an 11-foot-long male, on April 5 after a member of the public witnessed the sawfish swimming in circles in Cudjoe Bay. The animal is currently recovering at Mote Marine Laboratory and Aquarium in Sarasota, with hopes of eventually returning to the wild.
More than 150 sick sawfish have been observed since the crisis began. Circling sawfish have been sighted as far north as Palm Beach County, but scientists have not linked their behavior to that of fish in the Lower Keys.
Greg Fastenworth, who lives on Little Torch Key and has been spotting spinning fish and sharing videos on social media for months, spotted the 14-foot sawfish on a beach near Key West late last month. He said he saw him struggling.
“My wife started crying,” he said. “I wish things were better. I sit here and watch the ecosystem collapse, and I have no power to stop it.”
Whatever is going on, not only endangered sawfish and other marine life (more than 50 species and approximately 426 dead fish have been reported to the state), but also jobs related to sport fishing. The livelihoods of many people in the Lower Keys are also threatened.
Dr. Bouczek said some fishing guides have had their clients cancel trips because people are worried about whether the fish they catch will be safe to eat. The state says fish that exhibit unusual behavior should not be eaten.
One species of microalgae that has been detected, gambier discus, produces several toxins, including a compound responsible for a common fish poisoning in humans called ciguatera. However, it usually does not make the fish sick.
“It's been a stressful few months just putting together a very complex puzzle,” said Allison Dererschmidt, executive director of the Lower Keys Guide Association.
Alison Robertson, an associate professor of marine science at the University of South Alabama, cautions that there could be multiple causes of sick and dying fish. Fish in the Keys have had many toxins present over the years and may be predisposed to abnormal behavior due to previous exposure.
“We actually think that the combined effects of multiple toxins are causing the behavioral effects that we're seeing,” Dr. Robertson said.
Boucek, 39, who lives on a yacht in Marathon in the Middle Keys, checks the sensors on his boat every few days to collect fresh data.
One recent morning, Capt. Nick Labadie, a 33-year-old fishing guide, took Dr. Bousek to six locations around Sugarloaf Key, about 25 miles north of Key West, to pick up sensors identified by floating buoys. I read the GPS coordinates to track it. The first location, called Tarponberry, is where the spinning fish were first reported, Dr. Bousek said.
“When you talk to these 70-year-olds, they're like, 'I've never seen anything like this,'” he recalled.
He put on his swimming gear and dove in, yelling “Woo!” when he hit the cold water. He cleaned the tip of his one sensor and deployed another. Although he could clearly see down to the shallow bottom, he was still keeping an eye out for bull sharks, which he and Labadie agreed could be “very aggressive.”
Back on board, Dr. Bousek recorded his research by hand in pencil. He added a fixative to preserve the water sample and placed it in a cooler.
“Every day you think you have a certain pattern, but the next week that pattern completely disappears,” he says.
He was unable to find the sensor at another location where the water was more murky. But Dr Bousek noted encouraging signs, including the sighting of nurse sharks and sea bream at Sugarloaf Marina, where few fish had been seen for some time. Near Tarpon Berry, for the first time this season, he discovered mullet mud, the black specks that form when fish feed and stir the ocean floor.
He did not encounter any sawfish.
However, shortly after docking the boat and leaving the marina, rumors spread among fishing guides and scientists that a yarrow had washed up on a Key West beach. Tourists watched it die.
kitty bennett Contributed to research.