New Environmental DNA Test Helps Detect Elusive Small Hammerhead Sharks

A scientist at Florida International University has developed a novel test that can detect small hammerhead sharks without seeing or capturing them. The test works by identifying fragments of genetic material, or environmental DNA (eDNA), left behind by the sharks in water. This method allows researchers to track the presence of critically endangered species like scalloped bonnethead, scoophead, and Pacific bonnethead sharks, which have been difficult to study due to their scarcity and elusive nature. “Just by screening different locations along their distribution range from Mexico to Northern Peru, we can identify high-priority areas where conservation resources might be needed,” said Diego Cardeñosa, author of the study published in Frontiers in Marine Science.

These small-bodied hammerhead sharks once thrived in remote coastal habitats but have suffered severe declines primarily because of overfishing. Many sightings have become rare or nonexistent, such as the scalloped bonnethead last seen in Mexico in 1994 and the scoophead in 2007, highlighting the urgency for new conservation tools. Cardeñosa’s eDNA test provides essential data on the sharks’ distribution, even when traditional methods fail. It offers a non-invasive way to monitor populations by analyzing water samples collected in the field.

The test’s simplicity and effectiveness also enable long-term data storage and future studies. Once a water sample’s DNA is extracted and stored in a lab, it can be re-analyzed to detect other species that might have been present. This capability extends the potential applications of the method well beyond just hammerhead sharks, supporting broader biodiversity assessments. “It’s fascinating that you can take a simple water sample and know whether a species was there or not,” Cardeñosa said.