Review of the Status of Coho Salmon from Washington, Oregon, and California

Weitkamp, Laurie A.; Wainright, Thomas; Bryant, G.E.; Teel, David J.; Kope, Robert G.

doi:10.1201/9781439822678.ch10

Cited by 27 publications

(43 citation statements)

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“…This produced an equilibrium spawning abundance of approximately 3300 age 3 adults. This value falls within the range of documented abundances for small catchments in the Puget Sound region (Weitkamp et al 1995). Natural variability was incorporated by randomly selecting each vital rate value in the projection matrix for each year from a normal distribution within the reported means and SD (Knudson et al 2002).…”

Section: Methodsmentioning

confidence: 99%

Estimating the future decline of wild coho salmon populations resulting from early spawner die-offs in urbanizing watersheds of the Pacific Northwest, USA

Spromberg

Scholz

2011

Integr Environ Assess Manag

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Since the late 1990 s, monitoring efforts evaluating the effectiveness of urban stream restoration projects in the greater metropolitan area of Seattle, Washington, USA, have detected high rates of premature mortality among adult coho salmon (Oncorhynchus kisutch) in restored spawning habitats. Affected animals display a consistent suite of symptoms (e.g., disorientation, lethargy, loss of equilibrium, gaping, fin splaying) that ultimately progresses to death on a timescale of a few hours. Annual rates of prespawn mortality observed over multiple years, across several drainages, have ranged from approximately 20% to 90% of the total fall run within a given watershed. Current weight-of-evidence suggests that coho prespawn mortality is caused by toxic urban stormwater runoff. To evaluate the potential consequences of current and future urbanization on wild coho salmon, we constructed life-history models to estimate the impacts of prespawn mortality on coho populations and metapopulations. At the low (20%) and high (90%) ends of the range of observed mortality, model results indicated the mean time to extinction of localized coho populations in 115 and 8 y, respectively. The presence of productive source populations (i.e., unaffected by prespawn mortality) within a metapopulation reduced local extinction risk. However, as more populations within a metapopulation become affected by spawner die-offs prior to spawning, the source population's productivity declined. These simple models demonstrate the potential for rapid losses from coho populations in urbanizing watersheds. Because the models do not account for possible impacts of toxic runoff to other coho life stages, they likely underestimate the cumulative impacts of nonpoint source pollution on wild populations.

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Section: Methodsmentioning

confidence: 99%

Estimating the future decline of wild coho salmon populations resulting from early spawner die-offs in urbanizing watersheds of the Pacific Northwest, USA

Spromberg

Scholz

2011

Integr Environ Assess Manag

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“…Records indicate that peak river entry of coho salmon to this creek occurs from late-October to mid-November [55]. The brood class of this species returns on average at 3 years, but early maturing males return at 2 years; therefore, sampling provided 2 full cohorts, for parental brood years 2006 and 2007 and their adult offspring returning in 2008 to 2010.…”

Section: Methodsmentioning

confidence: 99%

Temporal variation in selection on body length and date of return in a wild population of coho salmon, Oncorhynchus kisutch

2012

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BackgroundA number of studies have measured selection in nature to understand how populations adapt to their environment; however, the temporal dynamics of selection are rarely investigated. The aim of this study was to assess the temporal variation in selection by comparing the mode, direction and strength of selection on fitness-related traits between two cohorts of coho salmon (Oncorhynchus kisutch). Specifically, we quantified individual reproductive success and examined selection on date of return and body length in a wild population at Big Beef Creek, Washington (USA).ResultsReproductive success and the mode, direction and strength of selection on date of return and body length differed between two cohorts sampled in 2006 and 2007. Adults of the first brood year had greater success over those of the second. In 2006, disruptive selection favored early and late returning individuals in 2-year-old males, and earlier returning 3-year-old males had higher fitness. No evidence of selection on date of return was detected in females. In 2007, selection on date of return was not observed in males of either age class, but stabilizing selection on date of return was observed in females. No selection on body length was detected in males of both age classes in 2006, and large size was associated with higher fitness in females. In 2007, selection favored larger size in 3-year-old males and intermediate size in females. Correlational selection between date of return and body length was observed only in 2-year-old males in 2006.ConclusionsWe found evidence of selection on body length and date of return to the spawning ground, both of which are important fitness-related traits in salmonid species, but this selection varied over time. Fluctuation in the mode, direction and strength of selection between two cohorts was likely to be due to factors such as changes in precipitation, occurrence of catastrophic events (flooding), the proportion of younger- versus older-maturing males, sex ratio and densities of spawners.

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“…By the early 2000s, many wild Chinook and coho salmon populations in the lower Columbia were considered to be extirpated (Good et al 2005) and the remaining wild fish were listed under the ESA, along with the steelhead and chum populations in the same geographic area. Although the specific mechanisms of hatchery-wild fish interactions were not assessed, the large numbers of hatchery fish released and the high harvest rates in fisheries targeting the hatchery fish were among the factors found to contribute to the poor status of these populations in the reviews leading to the final ESA listing decisions (Flagg et al 1995;Weitkamp et al 1995;Myers et al 1998;Good et al 2005).…”

Section: Factors That Contribute To Ecological Hatchery Risksmentioning

confidence: 98%

Factors that contribute to the ecological risks of salmon and steelhead hatchery programs and some mitigating strategies

Kostow

2008

Rev Fish Biol Fisheries

107

122

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State and federal agencies in the United States annually release millions of hatchery salmon and steelhead into public waters. Many of the hatchery programs are located in areas where the wild populations are now listed under the U.S. Endangered Species Act (ESA) (16 U.S.C.§ § 1531-1544). These hatchery programs pose genetic and ecological risks to wild fish populations. Genetic risks occur when hatchery and wild fish interbreed and usually occur within a taxonomic species. Ecological risks occur when the presence of hatchery fish affects how wild fish interact with their environment or with other species and may affect whole species assemblages. This paper reviews some of the factors that contribute to ecological risks. Important contributing factors include the relative abundance of hatchery and wild fish in natural production areas, hatchery programs that increase density-dependant mortality, residual hatchery fish, some physical advantages that hatchery fish can have over wild fish, and life history characteristics that may make some species especially vulnerable to the effects of ecological risks. Many of these risk factors can be mitigated by management activities that reduce the level of interactions between hatchery and wild fish. This paper concludes by recommending twelve mitigation strategies that may be useful when agencies need to bring hatchery programs into compliance with the take provisions of the ESA.

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Review of the Status of Coho Salmon from Washington, Oregon, and California

Cited by 27 publications

References 0 publications

Estimating the future decline of wild coho salmon populations resulting from early spawner die-offs in urbanizing watersheds of the Pacific Northwest, USA

Estimating the future decline of wild coho salmon populations resulting from early spawner die-offs in urbanizing watersheds of the Pacific Northwest, USA

Temporal variation in selection on body length and date of return in a wild population of coho salmon, Oncorhynchus kisutch

Factors that contribute to the ecological risks of salmon and steelhead hatchery programs and some mitigating strategies

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