Hatchery Fish Swim More Slowly, are More Vulnerable Than Wild Populations

By Jessica Estepa, E&E reporter
3/15/2014 9:58:39 AM

Hatchery fish are more likely to swim more slowly than their wild counterparts, a new finding that scientists hope will influence fisheries policy.

Researchers from Washington State University studied 100 fish from five different lines of rainbow trout. Each line had a varying degree of domestication: Some of the fish were more closely related to fish bred in hatcheries for more than a century, while others were descended from lines that became domesticated within the last couple of generations, making them more genetically similar to wild fish.

Over a period of 10 to 15 weeks, scientists studied the trout -- all of which were propagated on the university campus -- measuring them for size and swimming speeds.

According to the study, recently published in the journal Aquaculture, the fish from the more domesticated lines had higher growth rates. However, they moved at slower speeds than the wilder fish.

The study builds on previous research done at the university, lead author Kristy Bellinger said.

Such findings should have implications for how hatcheries are managed, especially in the Pacific Northwest, where hatchery fish are used to supplement declining wild stocks of steelhead and salmon, she noted. Because of their likelihood to swim more slowly, they are also more likely to be caught by predators.

Juvenile rainbow trout flowing out of a transport tank into a raceway. The Northeast Fishery Center at Lamar, PA raises brook and rainbow trout in partnership with the PA Fish and Boat Commission. (Credit: Flickr/U.S. Fish and Wildlife)

To Bellinger, that means using hatchery fish to boost the native stocks is inefficient and a waste of money.

There's an ongoing debate in the fishing community about hatchery fish versus wild fish, which has resulted in lawsuits in recent years from conservation groups that argue hatchery fish have negative impacts on the wild populations.

As policymakers wade into that argument, Bellinger said she hopes research like hers is taken into account.

"It's super frustrating," she said. "There is so much science that shows the differences between hatchery and wild populations, but it never seems to be taken into account for management policy."

Reprinted from ClimateWire with permission from Environment & Energy Publishing, LLC. 202-628-6500.

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