More than 200 studies across 40 years revealed large-scale salmon hatchery programs weaken wild salmon diversity and lead to wild population declines


||| FROM OREGON CAPITAL CHRONICLE |||


For much of the last century, fish hatcheries have been built in the Northwest, across the U.S. and around the world to boost fish populations where wild numbers have gone down. 

But an analysis of more than 200 studies on hatcheries programs meant to boost salmonid numbers across the globe – including salmon, trout and whitefish – shows that nearly all have had negative impacts on the wild populations of those fish. Most commonly, hatchery fish reduced the genetic diversity of wild fish, leading to poor health and reproductive outcomes.

The findings weigh into a sensitive topic with a big price tag. In the Northwest, hatcheries are supposed to be a solution to declining wild salmonid numbers, caused in large part by hydroelectric dams, overfishing, irrigation and climate change. In the Columbia River Basin alone, officials have spent billions of dollars on nearly 200 hatcheries as well as habitat restoration projects during the past 50 years to improve wild numbers, but research shows those programs are having an opposite effect.

The global studies, all undertaken between 1971 and 2021, were analyzed by scientists at the nonprofits Trout Unlimited, based in Virginia, and The Conservation Angler, out of Washington, along with the University of Washington, the University of Montana and the Université Laval, in Quebec, Canada. Their analysis was published in July in the journal Fisheries Management and Ecology.

Of the 206 studies the team analyzed, more than 80% revealed hatcheries programs had adverse effects on wild salmonids. Of the 3% of hatcheries globally that were found to benefit wild populations, the majority were stocked with wild fish who were bred and released in small numbers to boost severely depleted wild populations. 

John McMillan, science director at The Conservation Angler who worked on the analysis, said the team wanted scientists all over the world who are studying the same fish species to see the impact of hatcheries programs beyond their regions of study. He said despite an overwhelming body of research showing most hatcheries programs hurt wild fish populations, it’s often controversial to criticize such programs. 

“It’s frustrating from a scientific point of view, because you can see what the science suggests, but it’s understandable why we’ve been reluctant to move our position on hatcheries, because of the social implications,” he said. “This is one of those things, like climate change, where we have to sit back and think about our relationship with the animal, what it means to us and how much we want to give up so these animals can truly, potentially rebuild themselves.”

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