A Florida International University scientist has developed a groundbreaking test to detect rare hammerhead sharks without spotting them in the water. This method could transform conservation efforts for species on the brink of extinction.
The technique identifies traces of sharks in seawater, acting like faint biological footprints. It detects fragments of genetic material, revealing the animals’ presence without catching or disturbing them. In a study published in Frontiers in Marine Science, marine biologist Diego Cardeñosa showed how environmental DNA can help locate and protect endangered shark species.
Tracking elusive and endangered species
Small hammerhead species, including the scalloped bonnethead, scoophead, and Pacific bonnethead, have suffered dramatic population losses due to overfishing. Scientists struggle to find or study these sharks, leaving their habitats and movements largely unknown. Cardeñosa’s environmental DNA technique promises to change that by pinpointing where these critically endangered sharks still live.
“Screening different locations from Mexico to Northern Peru allows us to identify high-priority conservation areas,” Cardeñosa said. “Our immediate goal is to locate these three species, likely among the most critically endangered coastal sharks worldwide.”
Searching for the last refuges
Cardeñosa believes these species once thrived before overfishing decimated their numbers. Today, they survive in shallow, remote coastal regions where monitoring is difficult and fishing regulations are weak. His research focuses on Colombia’s Uramba/Bahía Málaga National Natural Park, one of the few remaining habitats for these sharks.
“You can drop a hook there and catch one or two of these species in ten minutes,” he said. Elsewhere, sightings remain almost nonexistent. The scalloped bonnethead was last recorded in Mexico in 1994, and the scoophead in 2007. In Honduras, one species recently reappeared after decades without a record.
“That shows how hard it is to find them,” Cardeñosa said. “We must act to protect them or risk letting them vanish.”
Preserving a piece of evolutionary history
For Cardeñosa, conservation carries deeper significance.
“These species represent some of the newest sharks on the evolutionary scale,” he said. “If they disappear, we lose a piece of our planet’s evolutionary history. Extinction is permanent, and that drives my work.”
A powerful tool for the future of marine science
Cardeñosa hopes environmental DNA research will raise awareness of these often-overlooked sharks and showcase the method’s potential.
“You can take a simple water sample and detect if a species was present,” he said. By revealing where hammerheads still exist, the technique guides conservation priorities and maximizes protection efforts.
Beyond hammerheads, water samples may hold genetic information about other marine life. Laboratories can preserve the DNA for years, enabling future researchers to study species that once swam in the same waters.
