Salmon & Survival
Why Native and Hatchery Salmon are Different
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The Coast Range Association
Salmon & Survival Why Native and Hatchery Salmon are Different |
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WHAT HATCHERIES ARE SUPPOSED TO DO
Hatcheries were originally intended to supplement salmonid runs by providing a haven for fish in the earliest stages of their life - from the newly fertilized egg to the young smolt ready to migrate out to sea. By taking the eggs out of the river and putting them in a hatchery, managers hoped to save the baby fish from predators, landslides, an inconsistent natural food supply and competition for that food. The thinking was that if hatcheries could keep more young salmon alive than nature did, then there would be more fish to feed in the limitless ocean and to return to the limitless demands of fishermen and canneries.
But the fish that hatcheries grow are different from their wild counterparts in ways that are evolutionarily meaningful - and ultimately negative for overall salmonid survival.
Wild fish are perfect actors of their evolutionarily successful survival strategy. Although between 50 and 90 percent of a wild fish's offspring die before migrating to sea, those that make it past their youth survive in high percentages to reproduce. As youngsters, the survivors forage efficiently along the river's bottom, flee when a predator comes sniffing around to eat them and disperse widely in the ocean. They return faithfully to their native streams to spawn, rounded and brightly colored to attract a mate. They tend to return to spawn later in the season and over a longer period and more of their offspring survive to be adults than do hatchery fish that spawn in the wild.
Hatchery fish, on the other hand, are grown largely to allow greater harvest. Hatcheries do get eggs past the roadblock that kills most of them in the wild - up to 95 percent survive to become smolts in a hatchery. But even offspring of the first hatchery generation abound in traits that help them survive in a protected hatchery rather than in a natural river.
This initial survival boost is intended to bolster dwindling wild runs, but those hatchery smolts fare worse than their wild counterparts in every subsequent stage of their life: fewer survive to adulthood, they have lower success in reproducing and substantially fewer of their offspring survive to adulthood. In the river, they are inefficient foragers, feeding near the surface and approaching predators (who they may mistake for hatchery managers coming to feed them). They make themselves a target to predators by clumping together. They do not travel far from each other in the ocean and also clump up when they return to spawn. Their dull colors are less likely to attract a mate in the wild and their early spawning time leaves their nests, or "redds," vulnerable to washouts in early fall freshets.
HOW HATCHERIES HARM
Hatcheries achieved the goal of keeping young fish alive. And for a while there were more fish in the sea. Then, in the 1970s, ocean conditions for salmon worsened off the coasts of Oregon, Washington and California. With the ocean less abundant for salmon, the limitations of hatchery fish became clearer. In the intervening decades, scientists and fisheries managers saw the myriad ways in which hatchery fish actually harm wild salmon rather than help them.
Scientists have monitored very few hatcheries and scientific methodologies for understanding how changing different pieces of a puzzle affects the whole were ignored. Through the mud of the vast hatchery experiment, however, it is clear that hatcheries and the fish they produce harm wild runs both ecologically and genetically.
According to the National Research Council, "in retrospect it is clear that hatcheries have caused biological and social problems. For example, hatcheries have contributed to the more than 90 percent reduction in spawning densities of wild coho salmon in the lower Columbia River of the past 30 years." (National Research Council, 1996)
| Ecological | Genetic Interbreeding |
| ·Competition for Living Space | ·Loss of Fitness |
| ·Reduced Disease Resistance | ·Lower Survival |
| ·Disease Introduction | ·Fewer Adult Spawners |
| ·Predator Attraction | ·Loss of Life History Diversity |
| Harvest |
| ·Harvest Rate on Hatchery Fish is too High for Wild Fish |
| ·Adult Spawner Objectives are Inadequate·Reduced Disease Resistance |
| ·Spawner Abundance Objectives by Watershed Are Not Achieved |
Hatchery fish, when they interact with wild salmonids, decrease the genetic diversity of the wild fish, compete with them for food and habitat, spread disease and promote increased predation. They exacerbate the effects of fishing by masking low numbers of wild fish and allowing greater harvest. Even catching a few extra wild fish among a mass of hatchery fish can imperil a particular deme when its population is on the brink. When wild and hatchery fish mate in the rivers, their offspring survive and reproduce substantially less successfully. That whittles away at the ability of the natural population to sustain itself - much less to recover.
Jim Lichatowich, one of the region's most respected salmon biologists, described this to a court in 2001:
"Each river and tributary has a discrete strain of fish, adapted through generations of natural selection to the local habitat and environment. When wild salmon mated with the transplanted hatchery fish, local adaptations such as resistance to disease were often diluted or lost. When hatchery-bred fish return as adults and interbreed with wild salmon, they can produce offspring that are less hardy than their purely wild counterparts. Hatcheries continue to pose genetic and ecological threats to wild populations. NMFS (National Marine Fisheries Service) identified 'negative effects of artificial propagation programs' as a factor contributing to the species' decline. Because hatchery fish diminish the fitness and diversity of salmon populations and cannot sustain themselves without the artificial and continual intervention of humans, wild Oregon coastal coho salmon will continue to need the protection of the ESA." (Lichatowich, 2001)
Lichatowich was summarizing what fisheries biologists have been saying in increasing numbers.
Others make similar points:
· "Puget Sound fish hatcheries which were supposed to offset dwindling salmon runs actually may have contributed to those declines." (Hatchery Scientific Review Group, 1999)
· Existing studies "provide strong evidence that the fitness for natural spawning and rearing can be rapidly and substantially reduced by artificial propagation." (Reisenbichler, et al, 1999)
· "It is clear that long-term (hatchery) supplementation programs whose primary goal is to provide a demographic boost to a natural population are particularly incompatible with the preservation of the fitness attributes of the original wild population." (Lynch and O'Hely, 2001)
The Oregon Department of Fish and Wildlife reported in a 1985 newsletter that hatchery coho were harming wild ones. The newsletter said that the hatchery added 50 percent more smolts to the river and, in the process, reduced the number of wild smolts by 50 percent. Despite the influx of hatchery fish, the total returning adult numbers did not increase and the offspring of those returning adults declined by 46 percent. The report concluded that "release of hatchery coho presmolts into coastal streams has hurt coho populations rather than helped them." (Solazzi, et al, 1985)
In nature, a mating population of hundreds or thousands of fish combines a wide variety of favorable genes. In a hatchery, however, just a few individuals provide the genes, offering a limited palette for nature to work with. But unlike the wild, the hatchery babies survive in great numbers and are thrown out to sea. If they spawn naturally with the wild fish, the overall diversity of genes in the population is significantly reduced. This is pointed out by Mark Chilcote in his study of hatchery and wild steelhead in Oregon: "Genetic differences may arise from the common situation that returning hatchery fish are the offspring of substantially fewer parents than is the case for wild fish returning to the same basin. For example, approximately 160 fish are used annually as broodstock for the Umpqua summer steelhead hatchery program. In contrast, the number of wild fish that spawn naturally in the North Umpqua basin is typically greater than 3,000 fish. Therefore, the genetic base for the hatchery return is approximately 80 families, whereas for the wild fish it is roughly 1,500 families." (Chilcote, 2002)
One of the most profound consequences of hatchery fish interacting with wild ones is the subsequent change to, and reduction of diversity in, the wild genes that evolved over millennia into the best possible fit for a given stream. Because those genes adapted so specifically over such a long time, in many cases those changes are decidedly for the worse. Researchers have documented ways in which those changes have made the wild fish less able to survive in the streams to which they adapted over millennia, return fewer adults to fill the spawning grounds and lose the diversity salmon have used for 40-50 million years as a hedge against extinction.