Can These Hedge Trimmers With Fins Avoid a Brush With Extinction?

With the model, they tested how habitat, fishing pressure and socioeconomics affect populations, ranking countries by sawfish extinction risk. What emerged as key for healthy populations of all sawfish species, the study found, is availability of mangrove habitat combined with facing less pressure from fishing.

Colin Simpfendorfer, a sawfish expert at James Cook University in Australia, commended the study, saying that “it’s not just an analysis of where, but also what needs to be done.”

Ms. Yan’s international research was complemented by the American team Ms. Graham led. That study, published in January in Endangered Species Research, showed that the smalltooth sawfish’s stronghold within the United States is still mainly restricted to Florida but it may be starting to expand. By tracking the fish with passive acoustic tags and an array of receivers, her team recently detected them as far north as Brunswick, Ga.

Though international trade in sawfish and their parts is banned under the Convention on International Trade in Endangered Species of Flora and Fauna, intentional killing and by-catch still occurs. And countries have an imperfect record at enforcing prohibitions on trade in the fish’s fins and teeth, which are still prized as trophies and used in some cultural settings.

When unintentionally captured — shrimp trawls are emerging as a key threat, with mitigation efforts being studied — sawfish often die needlessly because they are so tricky to untangle or release, says John Carlson, a sawfish researcher at the National Oceanic and Atmospheric Administration Fisheries. Their toothy rostrum “gets caught in everything. It’s their Achilles heel,” he says.

And with mangroves the key sites for aiding conservation, Dr. Carlson’s sawfish research is trying to understand why some mangrove patches, though superficially identical, are favored over others.

After two decades of increasing attention and targeted work by scientists and conservationists, “people’s appreciation of sawfish is really way up,” said Sonja Fordham, a co-author of Ms. Yan’s research and president of Shark Advocates International. But she cautions that “we still have a long way to go and it’s really a race against time.”