title: Quantitative threat analysis for management of an imperiled species: Chinook salmon (Oncorhynchus tshawytscha).
abstract: Chinook salmon (Oncorhynchus tshawytscha) have declined dramatically across the Pacific Northwest because of multiple human impacts colloquially characterized as the four "H's": habitat degradation, harvest, hydroelectric and other dams, and hatchery production. We use this conceptual framework to quantify the relative importance of major threats to the current status of 201 Chinook populations. Current status is characterized by two demographic indices: population density and trend. We employ path analytic models and information theoretic methods for multi-model inference. Our results indicate that dams most strongly affect variation in population density, while harvest and hatchery production most strongly affect variation in population trend. Comparable results arise when the sample size of the analysis is reduced to 22 Chinook populations within a smaller region typical of the scale at which salmon recovery planning is conducted. Results from these threat analyses suggest that recovery strategies targeting specific demographic indices, and those considering natural and human-mediated interdependencies of major threats, are most likely to succeed.
authors.affiliation: National Marine Fisheries Service, Northwest Fisheries Science Center, 2725 Montlake Boulevard E, Seattle, Washington 98112, USA. jhoekstra@tnc.org
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Hoekstra
authors.forename: Krista K
authors.initials: KK
authors.lastname: Bartz
authors.forename: Mary H
authors.initials: MH
authors.lastname: Ruckelshaus
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Moslemi
authors.forename: Tamara K
authors.initials: TK
authors.lastname: Harms
mesh_terms: D000818:Animals; D003247:Conservation of Natural Resources; D017753:Ecosystem; D006801:Humans; D007061:Idaho; D009922:Oregon; D011156:Population Density; D012474:Salmon; D014861:Washington