May 7, 2024 - News

The breeding patterns of hatchery salmon, explained

A photo of a salmon gliding across pebbles in a shallow river.

Photo: Courtesy of Oregon State University

Hatchery-born salmon struggle with reproduction — an issue that has puzzled researchers for years. But luckily that trait hasn't affected their offspring, according to a new OSU study.

Why it matters: Billions of dollars for salmon restoration efforts are being poured into the Pacific Northwest, and hatcheries play a big role in the future survival of the threatened Columbia River Basin species.

What they did: OSU researchers compiled 13 years' worth of family tree data from over 10,000 hatchery-born spring Chinook salmon in the McKenzie River, a tributary to the Upper Willamette River to determine each generation's fitness — the number of adult offspring a fish produces, according to a press release.

What they found: While hatchery-born salmon historically produce less offspring compared to their native counterparts when spawning in the wild, wild-born offspring of hatchery fish don't share that characteristic.

  • The study did not conclude whether the environment or genetics play a role in improved fitness but found that wild-born fish produce significantly more than their hatchery parents and about equal to their native peers.

The bottom line: The increased fitness of first-generation fish is a positive sign for conservation efforts, like re-establishing wild-born salmon populations via hatcheries.

Yes, but: Researchers warned that interbreeding between hatchery-born and wild salmon could potentially cause further reproductive fitness decline, and more research is needed in other river systems to test their findings.

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