title: Infectious disease, shifting climates, and opportunistic predators: cumulative factors potentially impacting wild salmon declines.
abstract: Emerging diseases are impacting animals under high-density culture, yet few studies assess their importance to wild populations. Microparasites selected for enhanced virulence in culture settings should be less successful maintaining infectivity in wild populations, as once the host dies, there are limited opportunities to infect new individuals. Instead, moderately virulent microparasites persisting for long periods across multiple environments are of greatest concern. Evolved resistance to endemic microparasites may reduce susceptibilities, but as barriers to microparasite distributions are weakened, and environments become more stressful, unexposed populations may be impacted and pathogenicity enhanced. We provide an overview of the evolutionary and ecological impacts of infectious diseases in wild salmon and suggest ways in which modern technologies can elucidate the microparasites of greatest potential import. We present four case studies that resolve microparasite impacts on adult salmon migration success, impact of river warming on microparasite replication, and infection status on susceptibility to predation. Future health of wild salmon must be considered in a holistic context that includes the cumulative or synergistic impacts of multiple stressors. These approaches will identify populations at greatest risk, critically needed to manage and potentially ameliorate the shifts in current or future trajectories of wild populations.
authors.affiliation: Pacific Biological Station, Fisheries and Oceans Canada Nanaimo, BC, Canada ; Forest and Conservation Sciences, University of British Columbia Vancouver, BC, Canada.
authors.forename: Kristina M
authors.initials: KM
authors.lastname: Miller
authors.affiliation: Biology Department, University of Victoria Victoria, BC, Canada.
authors.forename: Amy
authors.initials: A
authors.lastname: Teffer
authors.affiliation: Pacific Biological Station, Fisheries and Oceans Canada Nanaimo, BC, Canada.
authors.forename: Strahan
authors.initials: S
authors.lastname: Tucker
authors.affiliation: Pacific Biological Station, Fisheries and Oceans Canada Nanaimo, BC, Canada.
authors.forename: Shaorong
authors.initials: S
authors.lastname: Li
authors.affiliation: Pacific Biological Station, Fisheries and Oceans Canada Nanaimo, BC, Canada.
authors.forename: Angela D
authors.initials: AD
authors.lastname: Schulze
authors.affiliation: Pacific Biological Station, Fisheries and Oceans Canada Nanaimo, BC, Canada ; Biology Department, University of Victoria Victoria, BC, Canada.
authors.forename: Marc
authors.initials: M
authors.lastname: Trudel
authors.affiliation: Biology Department, University of Victoria Victoria, BC, Canada.
authors.forename: Francis
authors.initials: F
authors.lastname: Juanes
authors.affiliation: Pacific Biological Station, Fisheries and Oceans Canada Nanaimo, BC, Canada.
authors.forename: Amy
authors.initials: A
authors.lastname: Tabata
authors.affiliation: Pacific Biological Station, Fisheries and Oceans Canada Nanaimo, BC, Canada.
authors.forename: Karia H
authors.initials: KH
authors.lastname: Kaukinen
authors.affiliation: Pacific Biological Station, Fisheries and Oceans Canada Nanaimo, BC, Canada.
authors.forename: Norma G
authors.initials: NG
authors.lastname: Ginther
authors.affiliation: Pacific Biological Station, Fisheries and Oceans Canada Nanaimo, BC, Canada.
authors.forename: Tobi J
authors.initials: TJ
authors.lastname: Ming
authors.affiliation: Fish Ecology and Conservation Physiology Laboratory, Department of Biology, Carleton Univerisy Ottawa, ON, Canada.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Cooke
authors.affiliation: Environment Canada, Wildlife Research Division Delta, BC, Canada.
authors.forename: J Mark
authors.initials: JM
authors.lastname: Hipfner
authors.affiliation: Fisheries and Oceans Canada, School of Resource and Environmental Management, Simon Fraser University, Science Branch Burnaby, BC, Canada.
authors.forename: David A
authors.initials: DA
authors.lastname: Patterson
authors.affiliation: Forest and Conservation Sciences, University of British Columbia Vancouver, BC, Canada.
authors.forename: Scott G
authors.initials: SG
authors.lastname: Hinch
keywords: climate; coevolution; cumulative impacts; ecological impacts; infectious disease; microparasite; predation; wild salmon