Sawfish Acting Strange in the Florida Keys

Since October 2023, fish have been behaving in unusual ways between Bahia Honda and Sugarloaf Key. Tarpon, snook, permit, and other large fish have been swimming in circles, struggling to stay upright, and poking their heads out of the water, followed by their deaths. Scientists are wondering whether this mysterious occurrence is connected to washed-up sick and dead sawfish nearly three months later. The once salient member of fish populations in the southeastern United States was declared an endangered species by NOAA fisheries in 2003. Now, the smalltooth sawfish resides only off the coast of Florida making the recent deaths alarming news for the imperiled species. 

Dr. Michael L. Parsons, a biological oceanographer by training who specializes in harmful algal blooms and water quality, says he’s never seen anything like this before. Parsons’area of expertise is in gambierdiscus- a harmful algal bloom that causes the ciguatera toxin. Gambierdiscus is normally seen in the water column at around 30 cells per liter, but the Fish Wildlife Commission collected water samples of the bloom at 1,000 cells per liter in the Florida Keys. Parsons adds, “That’s more than we’ve ever seen so maybe something is going on with gambierdiscus with this. We’ve been focusing all our research efforts to see if gambierdiscus is related at all to these spinning fish and sawfish mortalities.” 

At first, Parsons and his colleagues thought the strange fish and sawfish behavior was just an unusual event, but as it persisted, they knew something bizarre was going on. Parsons explains that all the different fish being affected suggest that it’s something in the water. Low oxygen, red tide, high salinity, and pesticides have been ruled out as causal factors, however, there may be another explanation. Parsons adds, “We do know that gambierdiscus produces some toxins that are released into the water so we thought maybe it could be one of those or maybe an unknown toxin.”  

There are still questions as to whether the spinning fish and deceased sawfish are related. Parsons says, “We don’t know if it’s something different and just a coincidence or if the sawfish might be more sensitive or maybe getting exposed to the toxins more than the fish.” It’s difficult for labs to acquire samples of sawfish to run tests on possible toxins because they are an endangered species. Fortunately, Parsons adds, “We finally got some samples that are being run with one of our colleagues over at the University of South Alabama.” Parsons is hoping to get some answer soon, pointing out that a toxin signal does not necessarily mean that’s what caused the mortalities. Parsons explains it’s a matter of trying to put all the pieces together.  

As he and the team continue to search for answersParsons concludes, “We’re not seeing more reports of people getting sick eating the fish which suggests that maybe we’re not seeing more ciguatoxin moving into the food web. It might be related to gambierdiscus but completely different than a typical ciguatera type scenario. So, we’re really focusing on what’s happening in the water rather than what’s happening in the food web.”