Tracking Whales In Puget Sound Is As Easy As Following Genetic ‘Bread Crumbs’ Left Behind

Members of Puget Sound's south resident orca population. CREDIT: NOAA
Members of Puget Sound's south resident orca population. CREDIT: NOAA

Researchers at Oregon State University have worked out a way to detect and identify whales long after they move on — just by sampling the water.

When whales swim they leave behind a plume of genetic material in the environment: skin, poop and bodily fluids. If you know what to look for, you can use that DNA to figure out what kind of whale went by.

Scott Baker is associate director of the Marine Mammal Institute at Oregon State University’s Hatfield Marine Science Center. His research team tested this idea on orcas in the Salish Sea, collecting and testing water samples in their wake.

“We were quite surprised to find that even up to two hours afterwards — and that was the limit of our samplings, we were still able to detect that the whales had passed through that body of water,” Baker said.  

The research was published in the journal Frontiers.

Environmental DNA isn’t new technology. It has been used widely in freshwater systems to detect endangered and invasive species and to keep tabs on fish populations. But efforts to use this technology in the ocean are much newer.

“Application of eDNA to the marine environment is now trying to catch up,” he said.

Scientists have major questions about how the genetic material will move and how quickly it will degrade and disperse.

This discovery about the persistence of the DNA in seawater opens the possibility of detecting and studying other marine species, including those that are among the most elusive on the planet.

Baker says a DNA library exists for the nearly 90 known species of whales, dolphins and porpoises. It was developed to monitor the whale meat market in Asia — and make sure the varieties being sold were as advertised.

With this bank of genetic information in hand, Baker says doing these kinds of tests in open-ocean environment is the next step for refining the technology.

“Species like whales, whale sharks, sea turtles … these megafauna are actually pretty good candidates,” Baker said. “That being said, the ocean is a big place and the ocean is thin soup.”

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