title: Recurrent die-offs of adult coho salmon returning to spawn in Puget Sound lowland urban streams.
abstract: Several Seattle-area streams in Puget Sound were the focus of habitat restoration projects in the 1990s. Post-project effectiveness monitoring surveys revealed anomalous behaviors among adult coho salmon returning to spawn in restored reaches. These included erratic surface swimming, gaping, fin splaying, and loss of orientation and equilibrium. Affected fish died within hours, and female carcasses generally showed high rates (>90%) of egg retention. Beginning in the fall of 2002, systematic spawner surveys were conducted to 1) assess the severity of the adult die-offs, 2) compare spawner mortality in urban vs. non-urban streams, and 3) identify water quality and spawner condition factors that might be associated with the recurrent fish kills. The forensic investigation focused on conventional water quality parameters (e.g., dissolved oxygen, temperature, ammonia), fish condition, pathogen exposure and disease status, and exposures to metals, polycyclic aromatic hydrocarbons, and current use pesticides. Daily surveys of a representative urban stream (Longfellow Creek) from 2002-2009 revealed premature spawner mortality rates that ranged from 60-100% of each fall run. The comparable rate in a non-urban stream was <1% (Fortson Creek, surveyed in 2002). Conventional water quality, pesticide exposure, disease, and spawner condition showed no relationship to the syndrome. Coho salmon did show evidence of exposure to metals and petroleum hydrocarbons, both of which commonly originate from motor vehicles in urban landscapes. The weight of evidence suggests that freshwater-transitional coho are particularly vulnerable to an as-yet unidentified toxic contaminant (or contaminant mixture) in urban runoff. Stormwater may therefore place important constraints on efforts to conserve and recover coho populations in urban and urbanizing watersheds throughout the western United States.
authors.affiliation: Northwest Fisheries Science Center, NOAA Fisheries, Seattle, Washington, United States of America. Nathaniel.Scholz@noaa.gov
authors.forename: Nathaniel L
authors.initials: NL
authors.lastname: Scholz
authors.forename: Mark S
authors.initials: MS
authors.lastname: Myers
authors.forename: Sarah G
authors.initials: SG
authors.lastname: McCarthy
authors.forename: Jana S
authors.initials: JS
authors.lastname: Labenia
authors.forename: Jenifer K
authors.initials: JK
authors.lastname: McIntyre
authors.forename: Gina M
authors.initials: GM
authors.lastname: Ylitalo
authors.forename: Linda D
authors.initials: LD
authors.lastname: Rhodes
authors.forename: Cathy A
authors.initials: CA
authors.lastname: Laetz
authors.forename: Carla M
authors.initials: CM
authors.lastname: Stehr
authors.forename: Barbara L
authors.initials: BL
authors.lastname: French
authors.forename: Bill
authors.initials: B
authors.lastname: McMillan
authors.forename: Dean
authors.initials: D
authors.lastname: Wilson
authors.forename: Laura
authors.initials: L
authors.lastname: Reed
authors.forename: Katherine D
authors.initials: KD
authors.lastname: Lynch
authors.forename: Steve
authors.initials: S
authors.lastname: Damm
authors.forename: Jay W
authors.initials: JW
authors.lastname: Davis
authors.forename: Tracy K
authors.initials: TK
authors.lastname: Collier
mesh_terms: D000375:Aging / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D001646:Bile / Q000378:metabolism; D002947:Cities; D003625:Data Collection; D017753:Ecosystem; D004784:Environmental Monitoring; D005260:Female; D005393:Fish Diseases / Q000473:pathology; D005843:Geography; D005880:Gills / Q000187:drug effects / Q000378:metabolism; D006838:Hydrocarbons / Q000633:toxicity; D007306:Insecticides / Q000633:toxicity; D008670:Metals / Q000378:metabolism; D009026:Mortality; D009498:Neurotoxins / Q000633:toxicity; D017684:Oncorhynchus kisutch / Q000502:physiology*; D010063:Ovum / Q000187:drug effects / Q000502:physiology; D010575:Pesticides / Q000633:toxicity; D011084:Polycyclic Aromatic Hydrocarbons / Q000633:toxicity; D012098:Reproduction / Q000187:drug effects / Q000502:physiology*; D045483:Rivers; D013696:Temperature; D014861:Washington; D060753:Water Quality
chemical_list: D006838:Hydrocarbons; D007306:Insecticides; D008670:Metals; D009498:Neurotoxins; D010575:Pesticides; D011084:Polycyclic Aromatic Hydrocarbons