Researchers Detect Walking Sharks Using Environmental DNA
Scientists have successfully identified the presence of walking sharks in Indonesian waters by analyzing seawater samples for environmental DNA (eDNA), offering a non-invasive method to track these elusive predators. By filtering water for genetic material shed by the sharks, researchers from the University of Queensland and their partners can confirm the species’ location without needing to capture or visually spot them, according to findings published in the journal Environmental DNA.
How eDNA Technology Tracks Sharks
Environmental DNA technology allows marine biologists to detect organisms by identifying skin cells, waste, or other biological material left behind in the ocean. According to the National Oceanic and Atmospheric Administration (NOAA), this process involves collecting water samples, filtering them, and sequencing the captured DNA to match it against known genetic databases.
For the walking shark—a member of the genus Hemiscyllium that uses its pectoral fins to “walk” across the seafloor—this technology is particularly effective. Because these sharks inhabit shallow, complex reef environments that are often difficult for divers to survey, eDNA provides a reliable way to monitor their distribution across the Indonesian archipelago.
Why This Method Matters for Conservation
The primary advantage of eDNA is its ability to provide high-accuracy data with minimal impact on the animals. Traditional survey methods often require netting or heavy diving equipment, which can disturb the fragile coral reef ecosystems where walking sharks live.
By contrast, the eDNA approach allows for large-scale monitoring. Researchers can process multiple samples from different regions to map the sharks’ range efficiently. This is critical for the International Union for Conservation of Nature (IUCN), which monitors species like the epaulette shark. As habitats face pressure from climate change and coastal development, having an accurate, non-invasive census tool helps conservationists determine which areas require protected status.
Comparison of Survey Techniques
| Feature | Traditional Surveys (Visual/Netting) | eDNA Sampling |
| :— | :— | :— |
| Invasiveness | High (Potential animal stress) | Low (Water collection only) |
| Cost | High (Labor, equipment, travel) | Moderate (Lab processing required) |
| Accuracy | Dependent on diver expertise | Highly specific to genetic markers |
| Effort | High (Time-intensive search) | Efficient (Rapid sample collection) |
Future Applications for Marine Biology
The success of the Indonesian study suggests that eDNA could become a standard tool for monitoring various reef-dwelling species. Researchers are now looking to expand the use of this technology to detect other threatened shark and ray species across the Indo-Pacific.
According to the study authors, the next phase of research involves refining the sensitivity of the genetic markers to distinguish between closely related species of walking sharks. This level of precision will allow scientists to detect population shifts in real-time, providing an early warning system for species that may be disappearing from specific reef zones. Future efforts will focus on scaling these sampling protocols to cover broader geographical areas, ensuring more comprehensive protection for Indonesia’s unique marine biodiversity.