Last fall, during the annual salmon run, researchers collected salmon DNA from the air at Issaquah Creek, next to the Issaquah Salmon Hatchery in Washington. The study focused on Coho salmon during their fall migration. The idea began when a University of Washington scientist noticed fish and spray while hiking and wondered if genetic material could be recovered from the air.
The team placed air filters at several sites beside the stream and found Coho DNA up to 10 to 12 feet from the river. Filters were left for 24 hours on six different days between August and October, and four filter types were tested each time, including an open tub to catch settling particles. In the laboratory the researchers washed DNA from the filters and measured it with a Coho-specific tag using polymerase chain reaction.
The study, published in Scientific Reports, shows air and water eDNA are connected. The researchers combined air and water eDNA with the hatchery’s visual counts in a statistical model and found airborne eDNA concentrations rose and fell with observed fish numbers, suggesting the method can indicate where salmon are and their relative abundance. The team notes weather variables still need study, and the work received funding from two foundations.
Difficult words
- migration — regular seasonal movement of animals
- filter — material that removes particles from airfilters
- hatchery — place where fish are bred or raisedhatchery’s
- concentration — amount of something in one placeconcentrations
- model — simple mathematical or statistical representation
- abundance — large number or plenty of something
- polymerase chain reaction — laboratory method to copy and measure genetic material
- airborne — carried through the air as tiny particles
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- How could collecting DNA from the air help researchers or hatcheries study salmon?
- What weather factors do you think might change how much airborne DNA is found? Why?
- Would you trust this DNA method or visual counts more to estimate fish numbers? Explain your choice.
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