Mysterious Deaths of Endangered Sawfish and Other Fish Investigated in Florida Keys

Scientists are examining the puzzling deaths of endangered smalltooth sawfish and hundreds of other fish exhibiting unusual spinning behavior in the waters of the Florida Keys. Since late January, at least 41 dead sawfish have been found, coinciding with a larger fish kill impacting numerous species in the area since November.

The Florida Fish and Wildlife Conservation Commission (FWC) is leading the investigation into the cause of this 'unusual mortality event,' but so far, the reason remains unknown. Water samples and necropsy data have ruled out red tide toxins, communicable pathogens, dissolved oxygen levels, salinity, pH, temperature, and other ecological factors as the culprit.

Why this matters: The smalltooth sawfish is a critically endangered species, and this mysterious event has claimed the lives of at least 41 of these rare fish. Understanding the cause of these deaths is vital for protecting the remaining population and the well-being of the Florida Keys ecosystem.

Biologists from the FWC and Mote Marine Laboratory were able to rescue an 11-foot male sawfish from Cudjoe Key that was swimming in circles and transport it to Mote's facility for study. This marks the initial instance of an adult smalltooth sawfish being rescued in the Keys. Officials hope this rescue and rehabilitation effort will provide insights into the cause of the erratic behavior and high mortality rate.

Scientists are now focusing on a toxin called gambierdiscus, which can cause ciguatera poisoning in people who eat infected fish, as a potential cause. However, there have not been more reports than usual of ciguatera cases. Researchers are conducting fish exposure studies to confirm or reject this hypothesis.

NOAA Fisheries has launched an emergency response effort to try to save ailing sawfish, a complex task that has never been attempted before. "I haven't seen anything like this in my career, with mortalities being reported at a much higher scale and magnitude than we've ever seen," said Adam Brame, NOAA Fisheries' sawfish recovery coordinator.

The public has played a vital role in reporting sightings of distressed fish, aiding the investigation. Authorities are urging people to report any unhealthy, injured, or dead sawfish, as well as other fish exhibiting abnormal behavior, to the FWC hotline. As scientists work to unravel this mystery, the confirmed sawfish deaths may just be the 'tip of the iceberg,' according to Michael Crosby, president of Mote Marine Laboratory and Aquarium, as many more may have perished without being recovered or identified.

Key Takeaways

• Endangered smalltooth sawfish and other fish dying in Florida Keys, cause unknown
• At least 41 sawfish deaths since late January, part of larger fish kill since November
• Authorities investigating, ruling out common ecological factors as cause
• First-ever rescue of adult sawfish in Keys, to study erratic behavior and high mortality
• Public urged to report sightings, as many more deaths may have gone unrecovered