title: Ecosystem context and historical contingency in apex predator recoveries.
abstract: Habitat loss, overexploitation, and numerous other stressors have caused global declines in apex predators. This "trophic downgrading" has generated widespread concern because of the fundamental role that apex predators can play in ecosystem functioning, disease regulation, and biodiversity maintenance. In attempts to combat declines, managers have conducted reintroductions, imposed stricter harvest regulations, and implemented protected areas. We suggest that full recovery of viable apex predator populations is currently the exception rather than the rule. We argue that, in addition to well-known considerations, such as continued exploitation and slow life histories, there are several underappreciated factors that complicate predator recoveries. These factors include three challenges. First, a priori identification of the suite of trophic interactions, such as resource limitation and competition that will influence recovery can be difficult. Second, defining and accomplishing predator recovery in the context of a dynamic ecosystem requires an appreciation of the timing of recovery, which can determine the relative density of apex predators and other predators and therefore affect competitive outcomes. Third, successful recovery programs require designing adaptive sequences of management strategies that embrace key environmental and species interactions as they emerge. Consideration of recent research on food web modules, alternative stable states, and community assembly offer important insights for predator recovery efforts and restoration ecology more generally. Foremost among these is the importance of a social-ecological perspective in facilitating a long-lasting predator restoration while avoiding unintended consequences.
authors.affiliation: National Center for Ecological Analysis and Synthesis, 735 State Street, Santa Barbara, CA 93101, USA.; School of Aquatic and Fishery Sciences, University of Washington, 1122 Northeast Boat Street, Seattle, WA 98105, USA.
authors.forename: Adrian C
authors.initials: AC
authors.lastname: Stier
authors.affiliation: Conservation Biology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA 98112, USA.
authors.forename: Jameal F
authors.initials: JF
authors.lastname: Samhouri
authors.affiliation: Department of Integrative Biology, Oregon State University, Corvallis, OR 97331, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Novak
authors.affiliation: Conservation Biology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA 98112, USA.
authors.forename: Kristin N
authors.initials: KN
authors.lastname: Marshall
authors.affiliation: Conservation Biology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA 98112, USA.
authors.forename: Eric J
authors.identifier: 0000-0002-4359-0296
authors.initials: EJ
authors.lastname: Ward
authors.affiliation: Department of Biology, University of Florida, Gainesville, FL 32611, USA.
authors.forename: Robert D
authors.identifier: 0000-0002-6685-547X
authors.initials: RD
authors.lastname: Holt
authors.affiliation: Conservation Biology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA 98112, USA.
authors.forename: Phillip S
authors.initials: PS
authors.lastname: Levin
mesh_terms: D000818:Animals; D044822:Biodiversity; D017753:Ecosystem; D020387:Food Chain; D006801:Humans; D011157:Population Dynamics; D011235:Predatory Behavior
keywords: Restoration; apex predator; competition; food chain; hysteresis; intraguild predation; recovery