Robin Waples
Senior Scientist, NOAA Fisheries, Northwest Fisheries Science Center, Office of the Science Director

Pacific Salmon Extinctions: Quantifying Losses of Biocomplexity at the Level of Populations, Major Ecological, Life History, and Genetic Components, and ESUs

Abstract

It is becoming increasingly clear that biocomplexity plays a key role in shaping evolutionary processes and determining long-term stability of both species and ecosystems. Assessing and inventorying biocomplexity, however, is a challenging enterprise. This study represents the efforts of a group of scientists at the Northwest Fisheries Science Center to systematically characterize and quantify both extant and extinct components of biodiversity at multiple scales (populations, ESUs, and major ecological, genetic, and life-history types) in six species of Pacific salmon (Oncorhynchus spp.) from the Pacific Northwest and California. We estimate that about 30% of historic populations and perhaps a quarter of historical ESUs have been extirpated from this area since Euro-American contact.  Collective losses of major ecological, life-history, and genetic biodiversity components in these species is estimated to range from about 15% to 33%.  Nevertheless, within the study area remnants of over two-thirds of historical Pacific salmon populations persist, and considerable biodiversity remains at all scales. This suggests that we are at a turning point regarding the future fate of these species. If most remaining populations can be conserved, their still-rich store of genetic diversity should provide ample fuel upon which future evolutionary processes can act. On the other hand, if all populations currently listed as threatened or endangered under the US Endangered Species Act were to be lost, the fabric of biodiversity would be severely tattered, leading perhaps to widespread species-level collapses of salmon as well as associated ecosystem services. In any case, it is apparent that conservation of existing biodiversity and future evolutionary processes will depend on the ability of Pacific salmon to adapt to anthropogenically altered habitats.

Background Reading

Waples, R. S., R. G. Gustafson, L. A. Weitkamp, J. M. Myers, O. W. Johnson, P. J. Busby, J. J. Hard, G. J. Bryant, F. W. Waknitz, K. Neely, D. Teel, W. S. Grant, G. A. Winans, S. Phelps, A. Marshall, and B. Baker.  2001.  Characterizing diversity in Pacific salmon.  J. Fish Biol. 59(Supplement A):1-41.

Hilborn, R, T. P. Quinn, D. E. Schindler, and D. E. Rogers.  2003.  Biocomplexity and fisheries sustainability.  PNAS 100:6564-6568.

Waples, R. S., D. J. Teel, J. Myers, and A. Marshall.  2004.  Life history divergence in chinook salmon:  historic contingency and parallel evolution.  Evolution 58:386-403. 

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