TAMPA, Fla. — Scientists have been struggling to find out the cause of the abnormal behavior sawfish have been experiencing in the Florida Keys since last fall, but now they might have had a breakthrough.
The endangered species known for its long snout with pointy teeth sticking out of it, resembling a saw, has been seen spinning and dying in an "unusual mortality event." The Florida Fish and Wildlife Conservation Commission reports that 54 sawfish were killed. The National Oceanic and Atmospheric Administration announced an emergency response in March for the endangered animals.
Now, experts concluded the fish died from combined exposure to multiple toxins, according to an article by the National Geographic. Bethany Augliere reported that this could have originated from multiple species of dinoflagellates, which is a type of microscopic algae.
Based on the data, there were signs of disease or infection. Florida Fish and Wildlife also ruled out dissolved oxygen, salinity, pH, temperature and red tide as causes of the behavior or death.
Usually, the dinoflagellates live on seagrass and on the seafloor but for some reason they moved upwards, Augliere wrote. Sawfish also tend to stay on the ocean bottom since that's where they hunt for food.
The initial breakthrough came when Michael Parsons, a marine ecologist at Florida Gulf Coast University, found higher levels of a dinoflagellate in water samples, according to the article. The algae produces a neurotoxin called ciguatoxin. When humans eat seafood infected with this, they can experience vomiting, nausea and neurological symptoms, according to the National Organization for Rare Disorders.
Marine scientist Alison Robertson told Augliere that her team found multiple toxins in the livers and gills of symptomatic fish.
"That means high concentrations of the toxin-laden water passed through sawfish gills, causing the neurological impacts. They also ingested toxin-laden prey,' the article read.
Throughout the past few months, people have reported seeing the spinning fish in the Florida Keys.
In May, the Mote Marine Laboratory and Aquarium rescued a sawfish that was spotted swimming in circles. The animal ended up being euthanized after receiving critical care when its condition worsened.
That month, officials also reported a decrease in incidents of the deaths of distressed fish, according to the News Service of Florida.
Gill McRae, director of the commission's Fish and Wildlife Research Institution, mentioned the toxins in a statement in May.
“Everything is pointing to what is likely a naturally occurring species or multiple species of algae that produce low levels of toxins. These are neurotoxins that would be consistent with the behavioral changes that we've seen in the fish,” McRae said.
If you see any sawfish healthy, sick, injured or dead, you should call 844-472-9347 or email sawfish@fwc.com. You can also report abnormal fish behavior and fish kills to the hotline at 800-636-0511.