Researchers probe threats to salmonfly, a foundational bug

Joshua Murdock

ROCK CREEK – Jackson Birrell waded through thigh-deep water on a bucolic late-spring day last week, but unlike other anglers venturing into the swollen churn of spring melt, Birrell wasn’t seeking trout: He was instead looking for one of their seasonal delicacies, the giant salmonfly.

Each year in late May and early June, trout feast and anglers flock to waterways for the giant salmonfly hatch, when the ecologically vital bugs emerge from streams as nymphs and hatch out of the water into winged adults before reproducing and dying, leaving behind only the “shucks” they emerged from clinging to brush on the shoreline.

Growing up to 3 inches long, adult giant salmonflies are the largest of the stonefly family. They are so substantial that osprey, which generally consume fish, have been observed snatching up airborne salmonflies. As giant salmonfly populations decline in some streams across the West, Birrell and James Frakes, both researchers at University of Montana, are trying to understand what factors affect a bug that is essential to trout and the economies of fishing towns.

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In February, the pair launched The Salmonfly Project, a

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