Supplementation (Tech Recommend 4)

Problem Statement

Many naturally spawning salmon populations in the Columbia River Basin are severely depressed, declining, and will be extirpated unless effective remedial actions are taken immediately (Nehlsen et al. 1991; CRITFC 1992; Fryer and Mundy 1993).

Supplementation has been and is being used successfully to rescue endangered species such as the greenback trout (USFWS 1993), Lahontan cutthroat trout (USFWS 1992), and peregrine falcon (USFWS 1979, 1982) and for salmon in other locations (Figure 5B.2). Supplementation relies on the natural environment for the majority of the life cycle, and is less intrusive than expensive captive breeding programs. It is an appropriate tool for use with populations that are fragmented and declining, and where other remedial actions cannot be implemented quickly enough or on a scale that is large enough to halt further population losses. In these cases, survival of a portion of the natural population to the smolt life-stage would be increased by rearing in a hatchery. Conditions in the hatchery should simulate natural conditions as much as necessary to ensure that the original and supplementation groups are managed as one gene pool (Cuenco et al. 1993).

Supplementation has been successful in rebuilding salmon populations in Horse Linto Creek (Buck 1990; Farro 1993), and Red River (White and Cochnauer 1989; Cochnauer and Elam 1990). Volume II of this plan sets forth numerous tribal supplementation proposals. Guidelines and procedures for applying supplementation strategies to Pacific salmon have been developed (RASP 1992a; Cuenco et al. 1993) to ensure that the additional fish complement existing production and are able to survive and reproduce in the natural environment. Nevertheless, NMFS’s policies on artificial propagation under the Endangered Species Act have prevented implementation of tribal supplementation projects.


Supplementation can be used to increase survival of naturally spawning salmon populations in the Columbia River Basin during the egg-to-smolt stage. This increased survival, in combination with other actions (e.g., passage protection and habitat restoration), is sufficiently large to halt and reverse present population declines.

Recommended Actions/Tests


Implement supplementation projects that have met the screening criteria of RASP (1992b) and Cuenco et al. (1993). Volume II (the 1995 Subbasin Plans) of this plan identifies supplementation actions for watersheds above Bonneville Dam. Table 5B.4 identifies facilities needed for broodstock and acclimation/final rearing for supplementation and reintroduction (hypothesis/recommendation 5) actions called for in Volume II Subbasin Plans. High priority supplementation projects include:

  • Entiat River spring chinook
  • Methow Subbasin spring chinook
  • Clearwater Subbasin (Meadow Creek, McGruder corridor) spring chinook
  • Grand Ronde Subbasin (Catherine Creek, Lookingglass Creek, Upper Grande Ronde) spring chinook

Implement supplementation projects for other declining populations (identified in the Subbasin Plans and by CRITFC 1992) according to the RASP (1992a) and Cuenco et al. (1993) protocols. Review and implement tribal proposals for supplementation according to the Cuenco et al. (1993) protocol.

Develop experimental and monitoring programs in association with these projects to study the relationships between natural and supplemented components of the populations.


Continue the successful short-term programs and modify less successful short-term programs consistent with supplementation protocols.

Expected Results

Supplementation will 1) provide a refuge from severe environmental disturbance for a portion of native populations, 2) minimize further loss in genetic variability by stabilizing and potentially increasing the gene pool, and 3) restoring the role of salmon in affected ecosystems (Meffe and Carroll 1994; Brown 1995).

Salmon stocks at risk will be stabilized from further loss, with subsequent increases in abundance in naturally reproducing populations.

Institutional/Decision Structure

Supplementation projects will be coordinated through the U.S. v Oregon Production Advisory Committee according to the guidelines provided by Cuenco et al. (1993). Tribes and states will implement supplementation projects using the resources of the Mitchell Act, Lower Snake River Compensation Program, Northeast Oregon Production Project, Yakima Production Project, Nez Perce Tribal Hatchery, and other resources that may become available.


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