More than a dozen endangered sawfish have turned up dead in the Lower Keys in recent weeks amid an unusual fish kill that has also included goliath grouper, tarpon, stingrays and dozens of other species found dead or behaving erratically.
Early testing has so far ruled out harmful water conditions like low oxygen, temperature or salinity, but did detect elevated levels of a toxic algae found in ciguatera.
Fish that feed on reefs typically carry ciguatera because that’s where the algae naturally grows. The toxin can build up, which can make eating the fish dangerous. It’s rarely fatal, but symptoms including vomiting and neurologic damage, can be severe and take days or years to go away.
However, the toxin rarely harms fish, suggesting that a different species may be causing problems in the Keys. And having deaths across so many species is rare.
“It’s super unusual,” said Ross Boucek, a biologist for Bonefish Tarpon Trust, who said scientists worried that an extreme summer heat wave that pushed inshore temperatures above 100 degrees and bleached coral throughout the Keys could trigger other hazards. “We knew from the get go there would be weird stuff that happened afterwards. But we have no precedent to look back at.”
That means it’s still not clear if the events are related.
READ MORE: Biscayne Bay Is Busy and Polluted. So Why Are There More Sawfish?
BTT and the Lower Keys Guides Association first began getting reports of dead fish and unexpected behavior in early November, he said. Most were spotted between Bow Channel, near Sugarloaf Key, south to Key West.
Initially, the sick fish were only spotted at night and seemed to lose their equilibrium for a sustained time when they were stressed by lights or nets, Ross said. Soon, that odd behavior was observed during the day.
“Stingrays would be swimming upside down in circles,” he said. “When I first saw it, I was like whoa, rather than thinking it might be symptomatic of something larger.”
By mid December, as reports mounted, BTT and the Lower Keys Guides Association contacted the Florida Fish and Wildlife Conservation Commission and began collecting fish to test, Ross said.
In early January, scientists with Florida Gulf Coast University and the University of South Alabama — who specialize in algae toxicology — joined the effort and began looking for culprits.
A spokesperson for FWC said late Thursday he was still awaiting approval to release information based on questions provided on Wednesday.
In late January, Joyce Milelli was leading a paddle board tour near Geiger Key, about 10 miles east of Key West, when she spotted two dorsal fins and a large tail sticking out of mangroves.
“It was very windy and I told my customers, whoa, we have a big shark. We have to go way around it because if it moves, that’s not good,” she said.
As the group passed, the 11-foot sawfish remained still. Even though she'd never encountered a sawfish, Milelli said even she suspected something was wrong and returned after the tour ended. This time, the sawfish swam under her kayak and disappeared.
“It was like seeing a dinosaur come to life,” she said. “We were so happy. It was like coming back to life. It was the number one animal I’d wanted to see.”
But five days later, a colleague spotted it again where it had beached itself on a flat nearby and shot video before it died hours later. By the time Milelli and wildlife officers arrived to investigate, the next day, someone had cut off the rostrum.
"It was heartwrenching," she said.
At least 13 dead endangered smalltooth sawfish have been reported. The bottom feeding ray that looks like a shark once could be seen off coasts from the Carolinas to Florida. But overfishing and loss of estuaries and rivers that provided nurseries for baby sawfish caused numbers to plummet. Today sawfish can usually only be found in South Florida.
Along with sawfish, reports of sick or dead fish have included more than two dozen other species, from sturdy tarpon, permit, goliath grouper and stingray to smaller needlefish and sardines.
As reports climbed, news of the dead fish spread quickly around the small island chain, especially with the heavy toll high among sawfish. Milelli got reports of carcasses being found at Bahia Honda, on Big Pine and Sugarloaf keys, and at Key West beaches at Casa Marina, and Truman Annex. When she called the state hotline, a wildlife official told Milelli two 14-foot long females were among the dead.
Scientists plan to head out again next week to sample more water and look for changes in water, Ross said. In the meantime, he said, anyone who spots dead fish or suspicious behavior should call the state hotline at 1-844-4SAWFISH or 1-844-472-9347.
