For over 100 years, hatcheries have been producing fish in an effort to mitigate human impacts on the natural environment. Whether to increase stocks to fuel the demands of commercial and recreational fisheries, counteract the effects of habitat loss, or rescue species on the brink of extinction, hatcheries have been employed all over the planet as a tool to undo damage to fish populations caused by human beings.
Despite the mounting body of research demonstrating that hatcheries, once viewed by scientists and fisheries managers as a panacea, more often harm rather than benefit wild fish species, debate over the merit of fish hatcheries has raged on. Today, hatcheries are still a fixture across much of the world, despite the efforts of scientists and activists to inform the decisions of management agencies throughout North America, Europe, and beyond. But now, thanks to a recent study published in the scientific journal Fisheries Management and Ecology, advocates for a hatchery-free approach to fisheries management may have a powerful new weapon at their disposal.
The cooperative work of scientists from Trout Unlimited, U.S. and Canadian universities, and other organizations, the new study entitled “A global synthesis of peer-reviewed research on the effects of hatchery salmonids on wild salmonids,” evaluated over 50 years of scientific studies from around the world which investigated the impacts of fish hatcheries on wild salmonid populations. The study’s results were resounding, revealing that 83 percent of all published research determined that hatcheries had an adverse impact on wild fish populations. Perhaps even more alarming was the study’s discovery that a mere 3 percent of research during the last half century demonstrated a beneficial hatchery impact on wild fish populations.
Commenting on the study, Rob Masonis, Trout Unlimited’s Vice President for the Pacific Region noted, “This comprehensive analysis of peer-reviewed research underscores the need to make sure hatcheries are used judiciously for clearly defined purposes and with appropriate safeguards. Across the world, many salmonid hatcheries were built decades ago to support fisheries and replace natural salmonid production lost to dams and habitat destruction. Unfortunately, back then, managers lacked the scientific understanding we now have about the harmful impacts of hatcheries on the wild, naturally reproducing populations the hatcheries were intended to boost. If we are going to succeed in recovering depleted wild salmonid populations – which are more productive and resilient to climate change than hatchery fish – we need to make sure hatchery operations are aligned with wild population recovery goals. Without that alignment we risk undermining the enormous investments we are making in habitat restoration and other recovery actions, in addition to the wild fish themselves.”
The study’s authors took care to highlight that their review did not include research focused on the use of hatcheries in reintroducing extirpated or near-extirpated fish species, as their work was aimed at gaining insight on hatcheries’ impacts on existing, intact wild fish populations.
In a release, Helen Nellville, one of the study’s authors and a Trout Unlimited Senior Scientist noted, “We recognize that hatcheries play a significant role in specific regions where wild salmon and steelhead remain on the brink of extinction because of habitat degradation, including places where dams have drastically reduced wild production. In such places, hatchery salmon and steelhead, for instance, often serve as a vital lifeline to the lives, cultures, and well-being of tribal nations.”
Elsewhere, where situations are less dire and populations are not on the verge of extirpation, Nellville added, “Informed by the global science, we hope this work will motivate and support a deeper consideration of when and where hatcheries may, or may not, be an acceptable or effective tool, and how we can minimize harmful impacts to wild salmonid populations when they are justifiably used for compelling reasons.”
Even a cursory glance at the research reviewed as part of the study's 50-year analysis provides insight into the impacts of hatcheries on wild fish populations. Common amongst the more than 150 studies that concluded hatcheries had an adverse effect on wild salmonid populations were negative impacts such as reduced genetic diversity due to interbreeding with hatchery fish, reduced average size of wild fish, reduced overall abundance of wild fish populations, and reduced fitness for natural reproduction. Of the mere 7 studies that demonstrated a beneficial impact on wild fish populations, the majority revealed an overall increase in the abundance of naturally spawning fish.
The research reviewed as part of the study has been assembled into a publicly available database that will continue to be updated as new, peer-reviewed science is published.
Update: This story was updated to include examples of positive and negative hatchery impacts on wild fish populations present in the 50 years of research reviewed in the study.