More than a dozen endangered sawfish have died in the Lower Keys in recent weeks amid an unusual fish kill that 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 such as low oxygen, temperature or salinity, but found high levels of a toxic algae found in ciguatera.
Fish that feed on reefs usually carry ciguatera because that’s where the algae naturally grows. Toxins can build up, which can be dangerous for fish to eat. It is rarely fatal, but symptoms including vomiting and neurologic damage, can be severe and take days or years to resolve.
However, the toxin rarely harms fish, suggesting that other species may be causing problems in the Keys. And having so many species die off is rare.
“It’s very unusual,” said Ross Boucek, a biologist for the Bonefish Tarpon Trust, who said scientists are concerned that an extreme summer heat wave has pushed beach temperatures that above 100 degrees and bleaching coral throughout the Keys can trigger other hazards. “We knew from the get go there would be weird things that would happen afterwards. But we have no precedent to fall back on.”
That is, it is still unclear whether the events are related.
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BTT and the Lower Keys Guides Association first started getting reports of dead fish and erratic behavior in early November, he said. Most were seen between Bow Channel, near Sugarloaf Key, south of Key West.
At first, sick fish were only visible at night and seemed to lose their balance for a long time when they were stressed by lights or nets, Ross said. Soon, strange behavior was observed during the day.
“Stingrays swim upside down,” he said. “When I first saw it, I was like whoa, instead of thinking it might be a symptom of something bigger.”
In mid-December, as reports mounted, BTT and the Lower Keys Guides Association contacted the Florida Fish and Wildlife Conservation Commission and began collecting fish for testing, Ross said.
In early January, scientists at Florida Gulf Coast University and the University of South Alabama – who specialize in algae toxicology – joined the effort and began looking for the culprits.
A spokeswoman for the FWC said late Thursday that it was still awaiting approval to release information based on questions submitted 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 the mangroves.
“It’s 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 by, the 11-foot sawfish remained silent. Although he had never encountered a sawfish, Milelli said even he suspected something was wrong and returned after the tour. This time, the sawfish swam under his kayak and disappeared.
“It’s like seeing a dinosaur come to life,” he said. “We are very happy. It’s like being revived. This is the number one animal I want to see.”
But five days later, a colleague spotted it again beached on a flat nearby and shot video hours before it died. By the time Milelli and wildlife officials arrived to investigate, the next day, someone had cut the rostrum.
“Heartbreaking,” she said.
At least 13 dead endangered smalltooth sawfish have been reported. Bottom feeding rays that once looked like sharks can be found along coasts from the Carolinas to Florida. But overfishing and the loss of estuaries and rivers that provided nurseries for baby sawfish have caused numbers to plummet. Today, sawfish are generally found only in South Florida.
Along with sawfish, reports of sick or dead fish include more than two dozen other species, from hardy tarpon, permit, goliath grouper and stingray to smaller needlefish and sardines.
As the reports piled up, word of the dead fish spread quickly around the small island chain, especially among the high numbers of sawfish. Milelli got reports of bodies found in Bahia Honda, on Big Pine and Sugarloaf keys, and on Key West beaches at Casa Marina, and Truman Annex. When he called the state’s hotline, a wildlife official told Milelli that 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 the water, Ross said. In the meantime, he said, anyone who sees dead fish or suspicious behavior should call the state’s hotline at 1-844-SAWFISH (1-844-472-9347).
