At one time, the five living species of the sawtooth were found on the coastlines of 90 countries. Today, they are some of the world’s most threatened marine fish, and are already presumed extinct in some 46 countries, researchers from Simon Fraser University in Vancouver, Canada reported in a study published in the journal Science Advances.
There are 18 countries where at least one species of sawfish is missing, and 28 more where two species have disappeared. Three of the five species of sawfish are critically endangered, and the other two are endangered, the researchers warned.
Sawfish are a family of rays characterized by a long, narrow, flattened rostrum, or nose extension, lined with sharp transverse teeth, arranged in a way that resembles a saw, or a hedge clipper. They are found worldwide in tropical and subtropical regions and can reach lengths of about 7–7.6 meters (23–25 feet).
While the formidable saw they carry around with them looks alarming, the sawtooth is not considered dangerous to humans. They use their saws for feeding, digging out animals, and killing or maiming other fish. But they can inflict serious injuries with the saw when captured and defending themselves.
Overfishing and habitat loss
According to SFU researchers Helen Yan and Nick Dulvy, we could see complete extinction of the species if nothing is done to curb overfishing and to protect threatened habitats, such as mangroves, where sawfish can thrive, reports Phys.org.
“Through the plight of sawfish, we are documenting the first cases of a wide-ranging marine fish being driven to local extinction by overfishing,” Dulvy says. “We’ve known for a while that the dramatic expansion of fishing is the primary threat to ocean biodiversity, but robust population assessment is difficult for low priority fishes whose catches have been poorly monitored over time.”
“With this study, we tackle a fundamental challenge for tracking biodiversity change: discerning severe population declines from local extinction.”
The researchers have also identified “priority countries” where there is still a chance to save the surviving species. Conservation efforts should be made in Cuba, Tanzania, Colombia, Madagascar, Panama, Brazil, Mexico, and Sri Lanka, where protections could save the imperiled species.
Countries like the U.S. and Australia, which already have adequate protections and some sawfish, should be considered “lifeboat” nations.
“While the situation is dire, we hope to offset the bad news by highlighting our informed identification of these priority nations with hope for saving sawfish in their waters,” Helen Yan, a researcher in marine biodiversity and conservation at SFU, said.
We also underscore our finding that it’s actually still possible to restore sawfish to more than 70 percent of their historical range if we act now.”
