HatcheriesA Tool for Recovery, Not a Silver Bullet
Salmon hatcheries have been used across B.C. and the Yukon to support fisheries, compensate for habitat loss, and help rebuild threatened populations.
Hatcheries raise eggs and juveniles under controlled conditions, dramatically increasing survival during early life stages before releasing fish into the wild. The benefits are real. For example, hatcheries have contributed to the recent resurgence of Chinook in parts of Vancouver Island. But there are risks, too. Releasing large numbers of hatchery fish can alter natural patterns of competition, predation, disease transmission, and genetics within wild populations. While some impacts occur locally within individual rivers, there are also global consequences of releasing billions of hatchery salmon into the North Pacific Ocean, where total salmon abundance is now reaching historically high levels.
Different hatcheries, different goals
Not all hatcheries are created equal, in terms of their practices for sourcing eggs, releasing fish, and the number of fish they release.
Their practices are guided by their objectives, and some present more risks to wild salmon than others†.
Production hatcheries release large numbers of fry*, sometimes from non-local populations, to support fisheries. These fish are the most different from local wild populations they may interact with, and risk introducing unfit genes to wild salmon.
Supplementation hatcheries often have a dual goal of bolstering fisheries and enhancing local naturally spawning populations – as a result, they may periodically collect eggs from wild fish to ensure that the hatchery and wild strains are genetically similar.
Finally, conservation hatcheries rebuild depleted wild populations until they are self-sustaining again, eventually winding down enhancement efforts as populations rebuild, and usually collect eggs from the wild to minimize genetic risks.
*Fry: young salmon that have recently emerged from spawning gravel, before they begin their migration toward the ocean.
Three main categories of hatchery: conservation, supplementation, and production, differ in the number of fish they release and their impacts on wild salmon.
Tap to enlargeWhat kind of hatcheries operate here?
Most hatcheries in B.C. and the Yukon are supplementation hatcheries operated by the Department of Fisheries and Oceans, First Nations, or community stewardship groups. They vary in scale from hundreds of thousands of releases per year to a few fry raised in school classrooms.
The legend’s “>1M” markers refer to an average of more than one million salmon released per year over the past decade. Explore hatchery locations and statistics on the Pacific Salmon Explorer.
- Release sites
- Spawning channels >1M
- Hatchery releases >1M
Photo by Douglas Lofthouse, Salmonid Enhancement ProgramAnother Tool, Another Trade-off
Enhancement via artificial spawning channels, which provide optimal flows and gravel for spawning but don’t select broodstock or rear eggs, are not considered hatcheries but can have some of the same benefits and risks. In the Skeena River, spawner channels have bolstered returns of sockeye to Babine Lake in numbers that have exceeded the iconic Fraser sockeye in some recent years, but the erosion of smaller, unique co-migrating stocks has raised concerns about competition and increased harvest of at-risk populations†. Canada’s Salmonid Enhancement Program has seven of the largest artificial rivers/spawning streams in the world and most of their production is Sockeye Salmon.
Hatchery and wild salmon are genetically different
Hatchery fish are raised in controlled environments that improve their growth and survival.
Unlike wild salmon, they are not exposed to the same natural pressures early in life, such as predation, competition, and changing environmental conditions.
As a result, hatchery fish can become less adapted to surviving and reproducing in the wild. The extent of these differences depends partly on hatchery practices, including whether hatcheries regularly incorporate wild fish into their breeding programs and whether the eggs originated from the local environment. Regardless, a large body of research shows that hatchery salmon have lower survival and reproductive success in natural environments, even after only a single generation of being raised in hatcheries††.
Hatchery salmon tend to return to rivers where they were released and may interbreed with local wild populations, mixing their gene pools. While wild populations sustain a diversity of traits in their gene pool to buffer against the unpredictable environment, including timing of migrations and ages at return, hatcheries rarely mimic the same level of diversity. Hatchery populations tend to have more uniform traits and less genetic diversity†
When hatchery and wild populations interbreed, the wild gene pool can become skewed toward the uniform traits of the hatchery fish and away from its natural diversity†, a process that cannot be reversed. Less diversity often means less resilience to environmental change – including to climate change. A study from California suggests that there, hatchery influence was a factor in the loss of diverse run-timing variants that would have provided more resilience to hot summer temperatures droughts†.
The resurgence of Cowichan Chinook
Cowichan River Chinook illustrate both the promise and the limits of hatchery intervention. A hatchery, established in 1979 in partnership between Cowichan Tribes and Fisheries and Oceans Canada, ramped up production through the 1990s, releasing an average of 1.9 million juveniles annually by the 2000s – partly to offset declining marine survival. Despite this, numbers continued to fall, with just 540 natural spawners in 2009†.
Research revealed that hatchery-origin salmon were surviving at rates 6 to 24 times lower than their wild counterparts, undermining the assumption that hatcheries could simply make up for losses elsewhere†. Around the same time, momentum grew for a more holistic approach – restoring watershed health through habitat and flow improvements alongside a more moderate hatchery output. In recent years, the Cowichan River has seen record-high returns of Chinook, with over 22,000 natural spawners in 2024.
Cowichan Chinook have benefitted from improved flows, habitat restoration, and reduced harvest rates – a reminder that hatcheries can buy time, but they can’t substitute for the conditions wild salmon need.
Marked selective fisheries – the future of salmon fishing?
Hatcheries are often used to support commercial, recreational, and Indigenous fisheries by increasing the number of fish available for harvest and reducing pressure on wild populations.
However, hatchery production can also unintentionally increase fishing pressure on wild salmon. When large numbers of hatchery fish return to a region, fisheries are often expanded to harvest them, but wild salmon migrating alongside hatchery fish may also be caught. As a result, fisheries managed around abundant hatchery returns can still over-harvest smaller or at-risk wild populations, effectively creating a mixed-stock fishery where wild and hatchery fish are harvested together.
Marked-selective fisheries can offer a solution: before release, hatchery salmon are marked by clipping their adipose fin, providing a way for fishers to visibly distinguish hatchery fish from wild ones. Fisheries can then apply different regulations to marked and unmarked fish, allowing hatchery salmon to be retained while requiring wild fish to be released. This approach has been used in parts of southern British Columbia’s Chinook recreational fishery since 2021†. However, catch-and-release does not guarantee survival. Mortality of salmon that are captured and then released can be as high as 45%†, but varies widely depending on fishing methods and environmental conditions††. Fisheries and Oceans Canada has announced plans to expand hatchery marking programs, including a commitment to mark 90% of hatchery Chinook released in southern B.C. by 2027†, in part to support these more selective fisheries.
Sharing a finite ocean
Hatchery fish can increase competition for food and habitat in both freshwater and marine environments.
In rivers, hatchery smolts are often larger than their wild counterparts when released, potentially giving them an advantage in competition for limited resources†. Once they enter the marine environment, competition for limited food intensifies. it is critical that salmon gain energy to grow, avoid predators, complete long migrations, and successfully reproduce.
While hatchery fish do not always directly out-compete wild fish†, ecosystems can only support so many salmon. In parts of Alaska where more than 700 million hatchery fish are released, fewer wild pink salmon are surviving – likely because competition for food is higher than ever†.
Photo by Danny SwainsonMore salmon than ever before
Since 1975, the number of hatchery salmon released into the North Pacific has more than doubled, reaching over five billion fish in recent years.
As hatchery releases – particularly of pink salmon – have increased, salmon populations returning to rivers across North America have shown declining growth and survival, suggesting increasing competition for food in the open ocean†. Evidence of competition at sea has now been documented across all six Pacific salmon species, and may even affect broader marine ecosystems, including seabirds and whales that rely on similar food resources†. Canada contributes only about 5% of hatchery salmon released into the North Pacific – so if competition at sea is going to be addressed, it has to be on the world stage†.
Hatchery salmon released into the North Pacific on average over the past decade†
A Natural Experiment in Competition
Pink salmon are now the most abundant salmon species in the North Pacific and are increasing both through hatchery production and favourable ocean conditions related to climate change†. Pink salmon have a consistent two-year life cycle with greater abundances in the North Pacific in odd years than in even years. This pattern matches changes in growth, size, and survival of other salmon species, allowing scientists to more clearly document the negative impacts of competition with pink salmon.
Finding the right role for hatcheries
Hatcheries can provide important benefits by supporting fisheries and helping rebuild at-risk salmon populations.
They’ve become a lifeline in some places – allowing people to maintain long-held cultural relationships to harvesting salmon. But if not carefully managed, they can also undermine the long-term conservation and recovery of wild salmon. How hatchery and wild fish interact depends on factors like breeding practices, how many are released, and how hatchery fish are managed once they enter the natural environment, though most documented impacts on wild populations have been negative††. In a rapidly changing world, hatcheries will likely remain part of the future of Pacific salmon management – but they should not come at the expense of healthy wild populations and functioning ecosystems.
Hatcheries can buy time for salmon, but they cannot replace ecosystems that we fail to protect.
