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    Author(s): A. Agrawal; R.S. Schick; E.P. Bjorkstedt; R.G. Szerlong; M.N. Goslin; B.C. Spence; T.H. Williams; K.M. Burnett
    Date: 2005
    Source: NOAA Technical Memorandum NMFS: 1-25
    Publication Series: Scientific Journal (JRNL)
    PDF: Download Publication  (3.9 MB)


    Numerous Evolutionarily Significant Units (ESUs) of salmon and steelhead in California and the Pacific Northwest have been listed under the U.S. Endangered Species Act (ESA). In response, NOAA Fisheries convened Technical Recovery Teams (TRTs) to develop biological viability criteria for the listed ESUs. An understanding of biological structure is a critical first step to assessing population viability and potential persistence of ESUs (Meffe and Vrijenhoek, 1988; McElhany et al., 2000). TRTs evaluate population structure within each ESU under historical conditions, because this structure resulted from ecological and evolutionary dynamics that played out across the landscape before recent anthropogenic disruption. The historical population structure therefore represents a state for which we are most certain that the ESU persisted over long periods and is a "baseline" for evaluating the status of an ESU under current or projected conditions. Because populations that were important to ESU persistence in the past are likely to be important to ESU persistence in the future, understanding the historical template is critical to reducing uncertainty in assessments of current or future viability scenarios.

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    Agrawal, A.; Schick, R.S.; Bjorkstedt, E.P.; Szerlong, R.G.; Goslin, M.N.; Spence, B.C.; Williams, T.H.; Burnett, K.M. 2005. Predicting the potential for historical coho, chinook and steelhead habitat in northern California. NOAA Technical Memorandum NMFS: 1-25

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