Why Hatcheries Don’t Work and Why They are a Significant Factor for Wild Salmon and Steelhead Decline
Bonneville Hatchery on the Columbia River
This short summary describes the suite of hatchery impacts
Hatchery salmon are different from wild salmon in significant ways. Healthy wild fish populations are genetically diverse, shaped by natural selection to survive best in the changing watersheds their ancestors have returned to for centuries. Wild fish populations have adapted to the conditions in their watersheds, and they continue to evolve as those conditions change; this provides wild fish populations resiliency to climate change. Conversely, hatchery raised fish are shaped by artificial selection, are significantly less fit for survival in the wild, and generally have lower genetic diversity than wild fish. Hatchery fish are raised in an industrialized setting to maximize survival regardless of fitness. They are fed processed pellets by hand or by automated feed dispensers, provided with artificial shelters that are devoid of predators, and artificially spawned without regard to the importance and magic of mate selection or their fitness for successful spawning and survival in the wild. On the other hand, wild salmon must forage for food, find shelter, evade predators, and select mates. These natural selection pressures allow salmon to adapt to an ever-changing environment, creating more fit and resilient salmon with traits that are well-adapted to local conditions to survive to pass on their genes, even in the face of climate change.
Hatchery fish are generally released from only a few locations during a narrow time period. This can result in an unnatural distribution of fish, and fish predators, in the ecosystem. For example, a recent study determined that while South Puget Sound historically accounted for only 4% of wild Chinook, Puget Sound hatcheries release 25% of their Chinook into this area. The study also found that the hatchery Chinook appear to stay in in Puget Sound, unlike wild Chinook that spend 2-6 years foraging in the Pacific. This influx of fish into a concentrated area may add thousands of predators to the Puget Sound ecosystem, who may eat both hatchery and wild salmon, as well as other species, such as steelhead and forage fish important to the survival of wild salmon.
For much of their history, hatcheries were seen as a cure-all—a technological solution that would ensure a continued supply of wild fish despite overfishing and the degradation of natural ecosystems. Most hatchery programs historically failed to collect sufficient data to assess their environmental impacts. Within the past several decades, scientists concluded that hatcheries are one of the primary factors that have contributed to the decline of wild fish, along with overfishing, loss of habitat, and the construction of hydropower dams. In 1996, the National Academy of Sciences published a report that concluded that “In retrospect, it is clear that hatcheries have caused biological and social problems. For example, hatcheries have contributed to the more than 90% reduction in spawning densities of wild coho salmon in the lower Columbia River over the past 30 years.”[i]
Hatcheries harm wild fish populations in a variety of ways, including through genetic, ecological, fishery, and facility impacts. These harms occur when hatchery fish spawn with wild fish and decrease the genetic fitness, adaptability, and diversity of wild fish populations; when hatchery fish spawn with wild fish there is a loss of the wild fish's productive capacity in each spawning interaction; when an influx of hatchery fish overloads the carrying capacity of an ecosystem and the hatchery fish compete with wild fish for scarce habitat and food resources; when hatcheries artificially boost the fish population in a certain area, attracting more predators that eat both hatchery and wild fish; and when hatchery fish eat wild fish. Similarly, when hatchery production increases, so does fishing effort and catch by commercial and recreational fishers, leading to increased mortality for both hatchery and wild fish. Hatchery facilities also directly harm wild fish and the surrounding environment, including by blocking wild fish passage to upstream spawning habitats and by discharging effluent that has been contaminated with pathogenic fungi, bacteria, parasites, effluent, and medical treatments. Severe risks occur when diseases and pathogens are amplified and spread throughout the environment through both the propagation of hatchery fish and the release of contaminated water. In some state hatcheries, at-risk wild fish are intentionally killed for hatchery broodstock.
These harms to the environment are cumulative and proportionate to the abundance of hatchery fish relative to the abundance of wild fish. As populations of wild fish continue to decline and hatchery production increases, hatchery impacts on the remaining wild fish populations increase significantly.
[i] National Research Council, Committee on Protection and Management of Pacific Northwest Anadromous Salmonids, Upstream: Salmon and Society in the Pacific Northwest 304 (National Academies Press 1996)
