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UncertaintyWhat is the feasibility of reintroducing self-sustaining anadromous fish at each federal and non-federal project that currently blocks anadromous fish from historic habitat? Specifically, what is the feasibility of implementing adult and juvenile passage at dams that currently do not have passage?
ThemeHydrosystem flow and passage operations
SubthemeRestored passage/reintroduction
Sources Recommendations for the 2014 Program Amendment from USFWS
Criticality Level Priority
Rationale There are wide-ranging discussions in the Basin about the feasibility of reintroducing anadromous salmon and other fishes extirpated by the development of the hydrosystem. While this may be a laudable goal, there are numerous uncertainties associated with the endeavor. The extirpation of the original fish community took place many decades ago and novel biotic communities have assembled in response to new biophysical conditions. These communities are substantially different from those historically encountered and, in essence, they may be occupying nearly all the available niche space. Additionally, successful re-introduction of anadromous fishes into upper Basin areas will require adequate survival of migrating juveniles and adults through multiple dams and reservoirs in addition to potentially unfavorable conditions in the ocean. Before embarking on an endeavor to reintroduce native fishes above artificial barriers it will be necessary to evaluate the feasibility of establishing productive and resilient populations. The key question is whether a self-sustaining population can be established above the high-head dams in the upper Basin. Trap-and-haul and other technologies can move fish, but will this support a viable population? Resolving this question has a broad spatial scope and over time could have a large impact on abundance, productivity, and diversity of anadromous fishes. Prior to dam development the upper Basin supported sustainable populations, but whether it is possible to reestablish them in the currently modified system is less clear. Although passage technologies may be transferable, the hydraulic conditions at every dam are different. Studies to address this uncertainty are planned above Chief Joseph Dam and in some Willamette and lower Columbia River tributaries.

last updated: Jan 26, 2016