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 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

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.

Selection for Adult Size in Female Coho Salmon (Oncorhynchus kisutch)

1986 ◽  
Vol 43 (10) ◽  
pp. 1946-1959 ◽  
Author(s):  
L B. Holtby ◽  
M. C. Healey
Keyword(s):  
Coho Salmon ◽  
Pacific Salmon ◽  
Oncorhynchus Kisutch ◽  
Selective Advantage ◽  
Evolutionary Stable Strategy ◽  
Relative Fitness ◽  
Female Size ◽  
Adult Size ◽  
Stable Strategy ◽  
Wide Range

Several recent studies have presented evidence that large size confers a selective advantage to female Pacific salmon. Nevertheless, a wide range of female sizes is normally present in any spawning population. Two possible explanations exist for the observed range in female size. First, average female size might be determined by an optimizing process with variation around the optimum size due to individual differences in success at obtaining food. Second, various sizes of females might coexist as a mixed evolutionary stable strategy. Under the first explanation, females of sizes other than the optimum would display lower fitness whereas, under the second explanation, females of all sizes would be equally fit. We investigated factors affecting survival of eggs, fry, and smolts of coho salmon (Oncorhynchus kisutch) in Carnation Creek on Vancouver Island with a view to determining the relative fitness of different sized females. Egg-to-fry mortality was best explained by a model that included only the effects of stream bed scour and gravel quality. Including an effect of female size, expressed through depth of egg burying, worsened the model's predictive capability. We could find no evidence that the eggs of large females consistently survived better during incubation than those of small females. In fact, we observed three instances in which it appeared that the eggs of small females survived better. In Carnation Creek, large 1- and 2-yr-old smolts did not consistently survive better in the marine environment than small smolts. Thus, we were unable to demonstrate that the reproductive success of large females was consistently higher than that of small females, contrary to the hypothesis that female size is the result of an optimizing process. In Carnation Creek the observed range of female sizes probably represents an evolutionary stable strategy in which all sizes have equal fitness. We propose a model that predicts female size and variance in size based on the conflicting selective effects of gravel quality, scour, and competition for nest sites.

Fecundity of coho salmon (Oncorhynchus kisutch) and chum salmon (O. keta) in the northeast Pacific Ocean

1982 ◽  
Vol 60 (6) ◽  
pp. 1463-1469 ◽  
Author(s):  
Terry D. Beacham
Keyword(s):  
British Columbia ◽  
Chum Salmon ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Vancouver Island ◽  
Northeast Pacific ◽  
Queen Charlotte Islands ◽  
Kodiak Island ◽  
Salmon Stock ◽  
Northeast Pacific Ocean

Significant regional and annual variability in fecundity of coho salmon (Oncorhynchus kisutch) and chum salmon (O. keta) in British Columbia was detected during this investigation. A Kodiak Island (Alaska) coho salmon stock was more fecund than southern stocks in British Columbia and Washington. Fecundity ranged from 2450 to 2850 eggs per female at 53.6 cm postorbital–hypural length for Vancouver Island stocks to over 4400 eggs per female for a Kodiak Island stock at the same length. Chum stocks on Vancouver Island and the Queen Charlotte Islands generally had fecundities less than 3200 eggs per female at 58.8 cm postorbital–hypural length, whereas chum of equal lengths in mainland British Columbia stocks ranged from 3200 to 3450 eggs per female. Older chum and coho were usually more fecund than younger ones, but this difference could be accounted for by differences in mean length-at-age, fecundity being related to body size.

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.

Straying Patterns of Coho Salmon (Oncorhynchus kisutch) Stock from Southeast Vancouver Island, British Columbia

1992 ◽  
Vol 49 (9) ◽  
pp. 1843-1855 ◽  
Author(s):  
M. Labelle
Keyword(s):  
British Columbia ◽  
Selective Breeding ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Vancouver Island ◽  
Water Sources ◽  
Adult Age ◽  
Hatchery Fish ◽  
Genetic Makeup ◽  
Average Adult

Fourteen coho salmon (Oncorhynchus kisutch) stocks of wild and hatchery origin were tagged from 1985 to 1988 in nine streams within a 150-km coastal section of Vancouver Island. Tag escapements to natal streams were estimated from fence counts, stream surveys, and mark–recapture operations. On average, adult (age 3+) strays accounted for ~4.7% of escapements, but for > 40% of the adult escapements in some cases. Adult straying rate, averaged across all years and stocks, was < 2%. Straying rates tended to be lower for hatchery fish and highest for stocks subjected to certain enhancement practices. Adult strays escaped to streams 2–159 km from their home stream (average 15.7 km); over 50% escaped to streams < 7 km from their stream of release. Straying rates of jacks (age 2+) in a given year and that of their adult siblings during the following year were not related. Genetic makeup, age-at-return, run timing, and exposure to nonnatal water sources during the rearing stage did influence homing. Changes in natural straying patterns should be suspected where enhancement measures include flow controls, selective breeding, and exposure of fry to various water sources. Straying levels and stray contributions should be considered when estimating survival and exploitation rates

First report of Loma sp. (Microsporida) in juvenile coho salmon (Oncorhynchus kisutch) from Vancouver Island, British Columbia

1987 ◽  
Vol 65 (3) ◽  
pp. 751-752 ◽  
Author(s):  
Brad G. Magor
Keyword(s):  
British Columbia ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Vancouver Island ◽  
Maximum Intensity ◽  
First Report ◽  
Histopathologic Response

A species of Loma Morrison and Sprague, 1981 (Microsporida) was found in gills of smolt of Oncorhynchus kisutch from a hatchery on Vancouver Island, British Columbia. Prevalence of cysts was 28%. Maximum intensity was 84 cysts per fish. Histopathologic response of gills to cysts was minimal and localized where observed. This is the first report of a species of Loma in wild or captive fishes in western Canadian waters. The significance of its presence here is considered in light of a recent Loma epizootic in Alaska.

Coho salmon (Oncorhynchus kisutch) ocean migration patterns: insight from marine coded-wire tag recoveries

2002 ◽  
Vol 59 (7) ◽  
pp. 1100-1115 ◽  
Author(s):  
Laurie Weitkamp ◽  
Kathleen Neely
Keyword(s):  
Geographic Variation ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Principal Component ◽  
Distribution Patterns ◽  
Geographic Region ◽  
Small Scale ◽  
Adult Size ◽  
Wild Populations ◽  
Specific Distribution

We investigated geographic variation in the ocean migration of coho salmon (Oncorhynchus kisutch) by examining recovery locations of 1.77 million coded-wire tagged fish from 90 hatcheries and 36 wild populations along the west coast of North America. Principal component, cluster, and similarity analyses were used to reveal both large- and small-scale variation in marine recovery patterns. We identified 12 distinct ocean distribution patterns, each associated with a particular geographic region. Despite these distinct patterns, however, fish from a given population were widely dispersed in the coastal ocean. Recovery patterns for tagged wild populations were consistent with those of hatchery populations from the same region, suggesting that marine distributions based on hatchery populations are reasonable proxies for distributions of wild populations. These region-specific distribution patterns suggest unappreciated life history diversity for coho salmon in the marine environment. When combined with region-specific adult size variation, they suggest migratory differences earlier in the ocean residence period as well. These results provide a novel framework with which to view geographic variation in salmon ocean ecology, conservation, and management.

Sign in / Sign up

Export Citation Format

Share Document