With the model, they tested how habitat, fishing pressure and socioeconomics affect populations, classifying countries by the risk of extinction of sawfish. What emerged as the key to healthy populations of all species of sawfish, the study concluded, is the availability of mangrove habitat combined with facing less pressure from fishing.
Colin Simpfendorfer, a sawfish specialist at James Cook University in Australia, praised the study, saying that “it is not just an analysis of where, but also what needs to be done”.
Ms. Yan’s international research was complemented by the American team led by Ms. Graham. This study, published in January in Endangered Species Research, showed that the small sawtooth stronghold in the United States is still restricted mainly to Florida, but may be starting to expand. By tracking fish with passive acoustic tags and a series of receivers, his team recently detected them in the far north of Brunswick, Georgia.
Although the international trade in sawfish and its parts is prohibited by the Convention on International Trade in Endangered Flora and Fauna Species, intentional death and accidental capture still occur. And countries have an imperfect record of enforcing bans on fish fins and teeth, which are still appreciated as trophies and used in some cultural settings.
When caught unintentionally – shrimp trawling is emerging as a major threat, with mitigation efforts being studied – sawfish tend to die unnecessarily because they are very difficult to untangle or release, says John Carlson, National Sawfish Researcher Oceanic and Atmospheric Administration Fisheries. His toothy face “gets stuck in everything. It’s their Achilles’ heel, ”he says.
And since mangroves are the main places to help conservation, Dr. Carlson’s sawfish research is trying to understand why some mangrove patches, although superficially identical, are favored over others.
After two decades of increasing attention and targeted work by scientists and conservationists, “people’s appreciation for sawfish has really increased,” said Sonja Fordham, co-author of Yan’s research and president of Shark Advocates International. But she warns that “we still have a long way to go and it really is a race against time”.