Scientists can now detect the presence of white sharks using environmental DNA, or eDNA. Environmental DNA describes DNA strands found in the environment, not collected directly from a species' body.

Increasingly, researchers are turning to genetic markers to identify the presence of species in the environment, but until now, scientists struggled to isolate an eDNA signature for white sharks.

Through a series of trial and error, scientists were able to develop a new protocol for identifying white shark eDNA in marine samples.

Researchers from the University of California, Santa Barbara, California State University Long Beach, U.S. Geological Survey and Central Michigan University isolated identifiable genetic markers found in shark tissue. To test their protocol, scientists used genetic sequencing technology called digital droplet PCR to identify white shark eDNA in random samples.

The protocol successfully differentiated between positive samples and negative samples -- control samples, free of shark eDNA.

"We can now sample eDNA along the coast to make better maps and seasons for white sharks," Kevin Lafferty, a USGS ecologist and researcher with UCSB's Marine Science Institute, said in a news release. "And if we can do it for white sharks, we can do it for other marine species, too."

Surveys suggest white sharks have made a dramatic rebound in both the Atlantic and Pacific. Improved eDNA tracking technologies will help scientists show growing white shark populations and moving and interacting with the environment.

Research inspired by the new eDNA protocol could help scientists better understand shark-human interactions and minimize risks.

"One of the goals of this research is for a lifeguard to be able to walk down to the shore, scoop up some water, shake it and see if white sharks are around," said Lafferty.

Lafferty and his colleagues described their breakthrough this week in the journal Frontiers in Marine Science.

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