Evolutionarily Significant Unit (Institutional Recommend 6)


Reconsider the Evolutionarily Significant Unit (ESU) interim policy on the use of propagation.

The basis of the ESU is a genetics theory arguing that a salmon population’s fitness is reduced by the inflow of genes from hatchery bred salmon populations, even when the broodstock for the population comes from the same or adjoining populations. A recent report by the National Research Council supports tribal analysis of the ESU indicating that ESA policies should not stress reproductive isolation as an indicator of population distinctiveness or as a limitation on recovery (National Research Council 1995). The NRC Report also confirms tribal analysis that estimates of distinctiveness should be based on a variety of indicators including behavioral, morphological, ecological, and molecular information as well as genetic information because “a single kind of information will often fail to provide compelling evidence of distinctiveness. Determination of distinctiveness and the associated features of an independent future usual requires the careful integration of several lines of evidence” (National Research Council 1995).

While the ESU, developed in a more integrated format, may be an appropriate indicator of distinctiveness for listing purposes, it should not be used as a limitation on the recovery of a listed species in a particular habitat.

In light of the NRC Report, the NMFS should reconsider the ESU policy in a peer-reviewed process that addresses the use of propagation for species recovery as provided in the Endangered Species Act. (ESA Section 2(3), 16 U.S.C. §1532(3) provides that “conserve, conserving and conservation mean to use and the use of all methods and procedures [of ESA] are no longer necessary. Such methods and procedures include, but are not limited to, all activities associated with scientific resources management such as research, census, law enforcement, habitat acquisition and maintenance, propagation [hatcheries], live trapping, and transplantation….”)


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