You’d think if you had a chainsaw blade for a face, life might be pretty easy. But things have been tough for smalltooth sawfish in recent years.
In 2024 and 2025, these critically endangered animals were mysteriously washing up in the Florida Keys after something was causing them to spin in circles until they died. Scientists wondered if this weird behaviour was caused by toxic algae accumulating in the fish’s bodies, resulting in these strange neurological effects.
Now, in some good news for the species, a new study in Fishery Bulletin has revealed that Florida’s Indian River Lagoon – once a nursery for these funny-faced fish – may be supporting juveniles again.
Researchers from Florida Atlantic University’s Harbor Branch Oceanographic Institute and the Florida Fish and Wildlife Conservation Commission (FWC) attached acoustic tags to seven small juvenile smalltooth sawfish between 2020 and 2023.
Using these tags allowed them to see where the fish went over the next year or two – an important period because small juveniles stay in nursery areas for the first two to three years of their lives.
Their findings revealed that the juveniles strongly preferred an area in the South Fork of the Saint Lucie River. Of the days the sawfish were detected, they spent up to 87 percent of their time in a 0.15-square-mile area – smaller than Vatican City.
“These findings provide the first evidence that the Indian River Lagoon is once again functioning as a nursery for this endangered species,” says the study’s author Sarah Torre, Ph.D. candidate at FAU Harbor Branch. “While other coastal species, like juvenile bull sharks, also use broad estuarine nurseries, the strong fidelity of smalltooth sawfish to relatively small sections of the nursery during their first two years is unique.”
The little ones also seemed to prefer certain environmental conditions. Juvenile sawfish were most often seen in waters between 23.8 and 28.8 degrees Celsius (75 and 84 degrees Fahrenheit) and with a salinity of between 15 and 30 parts per thousand (ppt). For context, ocean water has an average salinity of 35 ppt. But if the temperature or salinity changed, some of the juveniles moved downstream temporarily.
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Knowing where juvenile sawfish spend their time gives experts an idea of where to focus conservation efforts.
“These findings highlight the ecological importance of this region, the need to preserve red mangroves and maintain healthy water quality, and the value of targeted conservation efforts to help smalltooth sawfish re-establish in their historical range,” says co-author Matt Ajemian, Ph.D., an associate research professor and director of the Fisheries Ecology and Conservation Lab (FEC) at FAU Harbor Branch.
Although the existence of this historic nursery within the Indian River Lagoon offers a glimmer of hope, sticking to such a small space means that the juveniles could be particularly vulnerable to threats to that area.
“After the significant losses we’ve seen in recent years, identifying places where juvenile sawfish are successfully surviving is crucial for the species’ future,” says senior author Gregg R. Poulakis, Ph.D., a research scientist at the FWC.
“This research gives managers something tangible to work with – specific locations and environmental conditions that are clearly supporting young sawfish.
"Protecting these areas and managing surrounding waterways with the needs of early life stages in mind could make the difference between continued decline and a slow but meaningful recovery for the species.”
Top image credit: Florida Fish and Wildlife Conversation Commission
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