Endangered Smalltooth Sawfish Mortality Event in South Florida
In late 2023, researchers began documenting abnormal fish behavior in the Lower Florida Keys (USA), with over 80 species observed spinning and swimming upside-down. Over 200 reports of affected sawfish were received, with 56 recovered mortalities. Necropsies were performed on most recovered sawfish with numerous samples and tissues collected for analysis. Necropsy data showed no apparent signs of a communicable pathogen (parasites, bacteria, viruses) that could have caused the spinning behavior and mortality. Results of water testing from the area indicated dissolved oxygen, salinity, pH, and temperature were not suspected to be the cause of the fish behavior or kills. Similarly, water testing found that more than 250 chemicals were either not detected or were below any biological thresholds. Water and benthic samples tested for microalgae found red tide (Karenia brevis) was not present, but Gambierdiscus spp. dinoflagellates and their associated ciguatera toxins were. Ciguatoxins were also observed in some fish tissues.
Reports of fish exhibiting spinning behavior declined over the summer and no sawfish have been reported to be spinning or dead since June. With the height of the emergency event appearing to now be over, the investigation continues through the collection and analysis of water and tissue samples. NOAA Fisheries and the U.S. Smalltooth Sawfish Recovery Implementation Team are currently working with numerous partners at aquariums, universities, state and federal agencies, and non-profit organizations including Florida Fish and Wildlife Conservation Commission, Ripley’s Aquariums, Havenworth Coastal Conservation, University of Southern Alabama, University of North Carolina Wilmington, Dynasty Marine, Florida Keys Aquarium Encounters, Terramar Productions, SeaWorld Orlando, and The Association of Zoos & Aquariums to determine the cause of the sawfish mortalities and plan for future similar events.
Your contribution will be used to fund the ongoing analyses of samples collected during the mortality event of endangered smalltooth sawfish in south Florida. Multiple partner agencies, organizations, and universities are working to evaluate organs and tissues collected during sawfish necropsies. These results will help the U.S. Smalltooth Sawfish Recovery Team better understand the causes of this event and inform future management decisions.
Other ways you can help:
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