Southwest Fisheries Science Center (U.S.)

"The Technical Recovery Team (TRT) for the North-Central California Coast Recovery Domain has been charged with developing biological viability criteria for each listed Evolutionarily Significant Unit (ESU) of salmon and Distinct Population Segment (DPS) of steelhead within the recovery domain. The viability criteria proposed in this report represent the TRT's recommendations as to the minimum population and ESU/DPS characteristics indicative of an ESU/DPS having a high probability of long-term (> 100 years) persistence. Our approach employs criteria representing three levels of biological organization: populations, diversity strata, and the ESU or DPS as a whole. Populations include both independent and dependent populations defined in Bjorkstedt et al. (2005), as modified in Appendix A of this report. Diversity strata are groups of geographically proximate populations that reflect the diversity of selective environments, phenotypes, and genetic variation across an ESU or DPS (Bjorkstedt et al. 2005). A viable ESU or DPS comprises sets of viable (and sometimes nonviable) populations that, by virtue of their size and spatial arrangement, result in a high probability of persistence over the long term. We provide background critical to understanding the context for viability criteria development in Chapter 1 of this report. Chapters 2 and 3 define viability criteria at the population and ESU/DPS levels, respectively. In Chapter 4, we apply the criteria to assess current viability, though with limited success due to the lack of appropriate, population-level time series of abundance. We emphasize that the focus of this document is looking forward to evaluating recovery, not assessment of current conditions"--Executive summary.

Technical Memorandum

National Marine Fisheries Service (NMFS)