Factors Affecting Puget Sound Coho Salmon (Oncorhynchus kisutch) Runs

1980 ◽  
Vol 37 (9) ◽  
pp. 1373-1378 ◽  
Author(s):  
S. B. Mathews ◽  
F. W. Olson
Keyword(s):  
Environmental Conditions ◽  
Coho Salmon ◽  
Important Determinant ◽  
Puget Sound ◽  
Oncorhynchus Kisutch ◽  
Factors Affecting

Summer streamflow, apparently affecting survival of zero-age coho salmon (Oncorhynchus kisutch), is shown to be an important determinant of Puget Sound run strength since 1952. Recently, hatchery production has also been a significant factor. Earlier studies indicated a relationship between rearing flows and coho run strength beginning in 1935. The persistence of the correlation between streamflow and run strength for more than 40 yr is noteworthy. Although the mechanism is unclear, survival of hatchery coho may also be positively dependent upon the same environmental conditions that affect stream-reared coho; a depensatory mortality relationship between abundance of hatchery coho and abundance of stream-reared coho is postulated.Key words: coho salmon, survival, run prediction, hatchery contribution

scholarly journals The role of coastal ocean variation in spatial and temporal patterns in survival and size of coho salmon (Oncorhynchus kisutch)

2001 ◽  
Vol 58 (10) ◽  
pp. 2021-2036 ◽  
Author(s):  
Alistair J Hobday ◽  
George W Boehlert
Keyword(s):  
Mixed Layer ◽  
Environmental Conditions ◽  
Coho Salmon ◽  
Mixed Layer Depth ◽  
Puget Sound ◽  
Oncorhynchus Kisutch ◽  
Vancouver Island ◽  
Coastal Ocean ◽  
Release Time ◽  
Adult Size

Interannual and decadal variability in ocean survival of salmon are well known, but the mechanisms through which environmental variability exerts its effects are poorly understood. Data on hatchery-reared coho salmon (Oncorhynchus kisutch) from individual releases (1973–1998) along the species' entire North American range were analyzed to provide information on survival and size. Three geographic regions (north of Vancouver Island, Puget Sound and Strait of Georgia, and the outer coast south of the tip of Vancouver Island) showed coherent trends in survival and size of returning fish. Within each region, multivariate nonlinear models were used to relate coho survival and final size to spatially and temporally tailored environmental variables at time periods of release, jack return, and adult return. The most important environmental variable, as indicated by the highest amount of variance explained, was a calculated proxy for mixed-layer depth, followed by sea level. In all regions, survival and adult size were most influenced by environmental conditions at the release time. A shallow mixed layer was associated with increased survival and decreased size in all regions. Improved understanding of the relationship between environmental conditions and size and survival of coho salmon provides insight into production patterns in the coastal ocean.

Factors Affecting Partial Migration in Puget Sound Coho Salmon

2014 ◽  
Vol 34 (3) ◽  
pp. 559-570 ◽  
Author(s):  
Jessica Rohde ◽  
Kurt L. Fresh ◽  
Thomas P. Quinn
Keyword(s):  
Coho Salmon ◽  
Puget Sound ◽  
Partial Migration ◽  
Factors Affecting

Natural Mortality Rate in Last Winter of Life of Coho Salmon (Oncorhynchus kisutch) Resident in Puget Sound

1974 ◽  
Vol 31 (6) ◽  
pp. 1158-1160 ◽  
Author(s):  
Stephen B. Mathews ◽  
Raymond Buckley
Keyword(s):  
Mortality Rate ◽  
Coho Salmon ◽  
Puget Sound ◽  
Oncorhynchus Kisutch ◽  
Fork Length ◽  
Natural Mortality

The natural mortality rate during a 3.5-mo period of the last year of life of coho salmon (Oncorhynchus kisutch) resident in Puget Sound was estimated to be 48% of the population at the beginning of this period. This estimate was based on recaptures of 29 fish out of 169, averaging 32 cm in fork length, tagged in January and early February, and 20 out of 61 averaging 41 cm tagged in May and early June, 1970.

Transferrin Polymorphism in Coho Salmon (Oncorhynchus kisutch)

1970 ◽  
Vol 27 (12) ◽  
pp. 2371-2373 ◽  
Author(s):  
Fred M. Utter ◽  
Warren E. Ames ◽  
Harold O. Hodgins
Keyword(s):  
Coho Salmon ◽  
Puget Sound ◽  
Oncorhynchus Kisutch ◽  
Columbia River ◽  
Single Locus ◽  
Potential Usefulness ◽  
Stock Identification ◽  
Transferrin Polymorphism

Six transferrin phenotypes observed in sera of coho salmon (Oncorhynchus kisutch) were interpreted as a reflection of three alleles — TfA, TfB, and TfC — at a single locus. The distribution of these alleles differed significantly among samples collected from streams entering Puget Sound and tributaries of the Columbia River, suggesting a potential usefulness of this system for stock identification.

Spatial and temporal factors affecting survival in coho salmon (Oncorhynchus kisutch) in the Pacific Northwest

1998 ◽  
Vol 55 (9) ◽  
pp. 2067-2077 ◽  
Author(s):  
Claribel Coronado ◽  
Ray Hilborn
Keyword(s):  
British Columbia ◽  
Pacific Northwest ◽  
Coho Salmon ◽  
Survival Rates ◽  
Oncorhynchus Kisutch ◽  
Dominant Factor ◽  
Spatial And Temporal Patterns ◽  
Factors Affecting ◽  
The Pacific ◽  
Ocean Conditions

Survival rates for coho salmon (Oncorhynchus kisutch) were estimated for all coded wire tag release groups in the Pacific Northwest between 1971 and 1990. The spatial and temporal patterns show considerable geographic variation, with most regions south of northern British Columbia showing declining survival since 1983, while northern areas have shown increasing survival during that period. The number of years of operation explained very little of the variation in survival, and many hatcheries showed major increases in survival after several years of operation. Survival of marked wild fish generally showed the same trend as hatchery fish. We conclude that the dominant factor affecting coho salmon survival since the 1970s is ocean conditions and that there are major geographic differences in the pattern of ocean conditions. The decline in survival seen in British Columbia and south over the last decade suggests that a major reduction in exploitation rates is necessary to maintain the populations.

Estimating the Population Dynamics of Coho Salmon (Oncorhynchus kisutch) Using Pooled Time-Series and Cross-Sectional Data

1985 ◽  
Vol 42 (3) ◽  
pp. 459-467 ◽  
Author(s):  
James L. Anderson ◽  
James E. Wilen
Keyword(s):  
Time Series ◽  
Population Dynamics ◽  
River Flow ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Cross Sectional ◽  
Factors Affecting ◽  
River Region ◽  
Parent Stock ◽  
Pooled Time Series

The population dynamics of natural and hatchery coho salmon (Oncorhynchus kisutch) were estimated for three regions, (1) Washington coastal, (2) Columbia River region, and (3) Oregon/California coastal, using pooled time-series and cross-sectional data. Two functional forms were compared: the Beverton–Holt and Ricker models. Both models yielded very similar results. In both cases, we found that the natural coho stock recruitment is significantly affected by parent stock level (positive), parent stock density (negative), river flow (positive), and hatchery smolt release (negative). The significant factors affecting hatchery coho salmon were smolt release level (positive), smolt release density (negative), and upwelling (positive).

Marine Mortality of Puget Sound Coho Salmon (Oncorhynchus kisutch)

1976 ◽  
Vol 33 (8) ◽  
pp. 1677-1684 ◽  
Author(s):  
Stephen B. Mathews ◽  
Raymond Buckley
Keyword(s):  
Coho Salmon ◽  
Survival Curve ◽  
Puget Sound ◽  
Survival Rates ◽  
Oncorhynchus Kisutch ◽  
High Survival ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Marine Life ◽  
Mortality Model

A model for natural mortality over the 18 mo of marine life of Puget Sound coho salmon (Oncorhynchus kisutch) is proposed, wherein the natural mortality rate M continuously decreases with increasing weight. Weight closely follows an increasing exponential function of marine age. The model is extended to account for ocean troll and sport fishing mortality and applied to data from marking studies of Puget Sound coho. The survival curve for marine life with only natural mortality declines rapidly for early ocean life and is quite flat over the ages fished. Recent high survival rates for hatchery coho released at a larger than normal size could be partially explained by this mortality model, although additional marking experiments are needed to separate the effects upon survival of size at release and time of release. The model applied to hatchery release-size strategy indicates that 70 g/fish might be optimal.

Effect of changing land use patterns on the distribution of coho salmon (Oncorhynchus kisutch) in the Puget Sound region

2008 ◽  
Vol 65 (10) ◽  
pp. 2138-2148 ◽  
Author(s):  
Robert E. Bilby ◽  
Lauren A. Mollot
Keyword(s):  
Land Use ◽  
Forest Cover ◽  
Coho Salmon ◽  
Landsat Imagery ◽  
Puget Sound ◽  
Substantial Reduction ◽  
Oncorhynchus Kisutch ◽  
Urban Land Use ◽  
Aerial Photographs ◽  
Population Increase

Population increase in the Pacific Northwest of North America over the last century has led to the removal of forests for various purposes. Evidence of salmon response to these alterations in land use is rare owing to a scarcity of fish population data and a high degree of interannual variation in abundance. We examined the relationship between the spatial distribution of spawning coho salmon ( Oncorhynchus kisutch ) and changes in land use from 1984 through 2001 at 84 sites in four rivers draining into northern Puget Sound. Changes in land use over this period were determined from LandSat imagery, county zoning designations, and aerial photographs. Substantial reduction in forest cover occurred in many of the index watersheds during this time. The proportion of salmon using sites subjected to increased urban land use over the study period declined about 75%. Increases were observed at forested sites and those with increased rural residential use. Maintaining salmon populations in rapidly developing areas may require the identification and protection of sites that support large salmon populations and steering development to areas supporting few fish.

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