| dbo:abstract
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- Pre-spawn mortality is a phenomenon where adult coho salmon, Oncorhynchus kisutch, die before spawning when returning to freshwater streams to spawn. It is also known as Urban Runoff Mortality Syndrome in more recent studies. This occurrence has been observed in much of the Puget Sound region of the Pacific Northwest. During fall migration, salmonids (trout and salmon) pass through urban watersheds which are contaminated with stormwater runoff. As the coho salmon pass through these waters, many will show symptoms of lethargy, loss of equilibrium and disorientation, and die within a few hours of showing these symptoms. These symptoms and behaviors are prevalent after rain events. Mortality often occurs before salmon have the opportunity to spawn, which is determined by cutting open female carcasses and observing for unfertilized eggs. Rates of pre-spawn mortality could impact the local salmon populations. Based on model projections, if rates continue, populations of coho salmon could become extinct within the next few decades. Weight of evidence suggests coho salmon pre-spawn mortality is due to exposure to stormwater runoff, although the exact contaminant or mixture that is responsible remains unknown. A negative correlation exists between the incidence of pre-spawn mortality and urban land use, specifically with the impervious surfaces, commercial property type, and local roads. Exposure to metals and petroleum hydrocarbons displayed some response to pre-spawn mortality, while exposure to pesticides, diseases, and water quality variables did not elicit this effect. This trend has not been observed in any other life history stage of the coho salmon nor in other salmon species in the Puget Sound region. (en)
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| rdfs:comment
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- Pre-spawn mortality is a phenomenon where adult coho salmon, Oncorhynchus kisutch, die before spawning when returning to freshwater streams to spawn. It is also known as Urban Runoff Mortality Syndrome in more recent studies. This occurrence has been observed in much of the Puget Sound region of the Pacific Northwest. During fall migration, salmonids (trout and salmon) pass through urban watersheds which are contaminated with stormwater runoff. As the coho salmon pass through these waters, many will show symptoms of lethargy, loss of equilibrium and disorientation, and die within a few hours of showing these symptoms. These symptoms and behaviors are prevalent after rain events. Mortality often occurs before salmon have the opportunity to spawn, which is determined by cutting open female c (en)
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