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Factsheet: Hatchery Salmon Interactions with Wild Salmon Populations

The interactions of hatchery-spawned salmon with wild-spawned salmon are immensely important for long-term management of fisheries resources. Wild Salmon Center Science Advisor Jim Lichatowich, author of Salmon Without Rivers, provides a context for the study of these interactions in Salmon Hatcheries: Past, Present and Future, a study prepared for the Oregon Business Council, intended to serve as a resource for Oregon policy leaders. The following points are abstracted from his research and synthesis of existing scientific documentation.

Domestication

Hatcheries are designed with contradictory missions: The fish they produce must survive and thrive in a hatchery environment, which is controlled and protected; they also must survive in rivers and oceans with predators and competitors. For more than 100 years in the Pacific Northwest, hatcheries produced domesticated salmon, which were selected on the basis of traits that were beneficial for survival in the hatchery itself. Such selection increases fitness in the hatchery, but often decreases fitness in the natural environment. (Campton, D. E. 1995. Genetic effects of hatchery fish on wild populations of Pacific salmon and steelhead: What do we really know? American Fisheries Society Symposium 15: 337-353, Bethesda, MD)

Loss of diversity

Hatcheries use economies of scale to reduce costs. They rely heavily on a few large broodstocks to produce the eggs and roe needed for artificial propagation. When there are major disruptions in one stock or at one period, production can suffer calamitously. As well, there is a loss of genetic diversity. There are no "seed banks" for salmon genetic diversity to ensure a broader genetic pool for hatchery production – other than the existing wild populations, which are heavily stressed by overfishing and habitat loss.

High juvenile survival, few adult returns

Possibly due to domestication effects, hatchery salmonids tend to have rates of juvenile survival (egg-smolt) that are higher than wild salmon, but lower survival in the smolt-adult phases. Most hatcheries measure success only on the basis of the number of juvenile salmon released, not the number of adult returns. This is only measuring one-half of the hatchery mission. (Oregon Department of Fish and Wildlife (ODFW). 1999. Fish hatchery purposes, goals and objectives. Portland, OR.)

Unintended consequences of broodstock selection

Historically, little attention was paid to broodstocks. Hatcheries simply required salmon eggs, in sufficient numbers to meet production goals. Eggs were moved between rivers and hatcheries, and all the eggs from early returning fish were collected. This selection for early maturation-return eventually led to hatchery broodstocks that attempted to spawn several weeks before their wild counterparts, either crowding out native wild fish or suffering high mortality because they were out of synch with river flows. Only recently have techniques for maintaining genetic traits in broodstocks been adopted. (Kapuscinski, A.R. and L.D. Jacobson. 1987. Genetic guidelines for fisheries management. Dept. of Fisheries and Wildlife, U. of Minnesota. Sea Grant Publication.)

Vulnerability to disease and parasitism

Transfer of hatchery fish between watersheds was once pervasive, although it has been reduced in recent years. What was not considered was that diseases and parasites are crucial ecosystem attributes. Fish native to a watershed with endemic parasites may develop resistance to them; fish not native may be very vulnerable. Between 1966-1975, one million Oregon Coast juvenile steelhead (O. mykiss) were released into the Willamette River Basin. No returning adults were ever observed. The reason was the presence of Ceratomyxa shasta¸ a parasite endemic to the Willamette that is absent in the coastal rivers. The coastal steelhead were highly susceptible to the parasite, whereas Columbia Basin stocks were resistant. (Wade, M. 1986. The relative effects of Ceratomyxa shasta on crosses of resistant and susceptible stocks of summer steelhead. Oregon Department of Fish and Wildlife, Research and Development Section, Corvallis, OR.)

If hatchery fish do survive to spawn with native fish, the result may be a lowering of the resistance of native fish to the disease or parasite. (Hemmingsen, A. R., R. A. Holt, R. D. Ewing, and J. D. McIntyre 1986. Susceptibility of progeny from crosses among the three stocks of coho salmon to infection by Ceratomyxa shasta. American Fisheries Society 115: 492-495, Bethesda, MD.) In Fishhawk Creek, on the Oregon Coast, a non-native stock of hatchery coho that was vulnerable to C. shasta was stocked for 12 years, from 1965-1976. Apparently, some of these fish survived to spawn with wild fish endemic in the watershed, and by 1980 the Fishhawk Creek coho were more vulnerable to C. shasta than nearby populations where non-native coho were not stocked. (Wade, M. 1987. ibid)

Hatchery overproduction during periods of low ocean productivity

Ocean productivity periods fluctuate broadly within cycles. Hatchery production, on the contrary, tends to operate on fixed production schedules. The result is that fixed levels of production come into conflict with varying levels of ocean productivity. Lichatowich speculates that hatchery releases may exceed ocean capacity at some periods. Because hatchery fish survive in the ocean at only one-half the rate of wild fish, the priority during periods of low ocean productivity should be to fill the limited capacity with wild salmon. Conversely, during periods of high ocean productivity, it may be possible to raise hatchery production accordingly.

How can hatcheries be run more safely?

A concept paper on "landscape hatcheries" was released in December 2003 by Trout Unlimited, available online at the TU website. In this paper by Jim Lichatowich, Rick Williams, Phil Mundy and Matt Powell, a proposal is made for a landscape approach in designing and maintaining hatcheries. The authors describe how hatcheries can be made ""art of a watershed, part of the landscape" by ensuring that their operations are in concert with the natural environmental conditions, constraints and assets of the stream system. This document is a valuable one in describing a way out of the current hatchery dilemma that does not rely on shutting down hatcheries, but ensures that they are managed effectively to protect and ultimately restore truly wild, native salmonid populations.