Marine Survival of Coho Salmon (Oncorhynchus Kisutch) in Washington State PDF Download
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Author: Jessica L. Beetz
Publisher:
ISBN:
Category : Coho salmon
Languages : en
Pages : 109
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Book Description
Author: Jessica L. Beetz
Publisher:
ISBN:
Category : Coho salmon
Languages : en
Pages : 109
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Book Description
Author: Sean M. Cochran
Publisher:
ISBN:
Category : Coho salmon
Languages : en
Pages : 110
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Book Description
California coho salmon Oncorhynchus kisutch populations are at low abundance and factors governing recruitment variability remain unclear. Changes in freshwater habitat that increase juvenile growth and size of salmon outmigrating to sea (smolts) may improve ocean survival. The best data to evaluate this among wild coho salmon populations in California come from life-cycle monitoring (LCM) stations. This study investigated whether marine survival is size-dependent (larger individuals within a cohort have higher marine survival) and whether sites and years with higher growth have higher marine survival across five LCM locations. I tested for size-dependent survival using two techniques: comparing the size of outmigrating smolts and back-calculated smolt sizes from scales of adult fish that survived to return; and using information from fish that were tagged as smolts and survived to return as adults. Analyses comparing smolt sizes back-calculated from adult scales and observed lengths from smolt traps indicated that within-year size-dependent mortality at sea occurred among many outmigrant cohorts, while analyses using smolt lengths of recaptured adult fish tagged as juveniles did not indicate any within-cohort size-selective mortality at sea. Potential explanations for the conflicting results include errors in scale back-calculation; smolts growing in habitats below smolt traps prior to ocean entrance; and fish with alternative juvenile life histories that were unaccounted for in outmigrant sampling surviving and contributing to the adult populations. In regressions across sites and years, marine survival was positively associated with early marine growth measured from the scales of surviving adult salmon and in some instances marine survival was also positively associated with mean fork length of outmigrating smolts. Although size may be an important determinant of ocean survival, this study shows that comparison of back-calculated smolts sizes from scales of adult fish and observed lengths of smolts at an upstream trapping location are unreliable approaches for testing size-selective mortality. This study also provides support for expanding studies at LCM stations to determine how juvenile coho salmon use habitat downstream of migrant trapping locations.
Author: Grace Katherine Ghrist
Publisher:
ISBN:
Category : Coho salmon
Languages : en
Pages : 77
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Overwinter survival for all three cohorts and all life histories ranged from 25-73%. In cohort one, overwinter survival for spring migrants was greater than the early migrants: overwinter survival was between 38-53% for spring migrants (depending on analysis assumptions) compared to 26% for early migrants; overwinter survival for the two life histories was indistinguishable in the other two cohorts. Apparent marine survival, including all cohorts and life histories ranged from 1.6-4.9%. Marine survival was indistinguishable between juvenile life history strategies likely due to small sample sizes. A power analysis performed with simulated data, to estimate the sample size of fall tags necessary in order to distinguish between juvenile life histories; this ranged from 3500-6000 tags. The transition probability to the jack state ranged from 1.5-55.8% and was indistinguishable between life history strategies. Multistate models provide the opportunity to incorporate life history diversity into estimates of population demographic rates. Use of these models and ongoing monitoring effort will continue to add new insights into Coho Salmon life history variation and the consequences for populations.
Author: James Ray
Publisher:
ISBN:
Category : Coho salmon
Languages : en
Pages : 22
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Author:
Publisher:
ISBN:
Category : Estuaries
Languages : en
Pages : 340
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Author:
Publisher:
ISBN:
Category : Fisheries
Languages : en
Pages : 416
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Author: J. L. Specker
Publisher:
ISBN:
Category : Coho salmon
Languages : en
Pages : 5
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Book Description
Author:
Publisher:
ISBN:
Category : Estuaries
Languages : en
Pages : 340
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Book Description
Author: Ryan Jordan Briscoe
Publisher:
ISBN:
Category : Coho salmon
Languages : en
Pages : 114
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Book Description
"Correlation analyses and stepwise regression models were run to examine relationships between Auke Creek coho salmon marine survival, scale growth, and a number of physical and biological covariates: local sea surface and air temperatures, local precipitation, the Pacific Decadal Oscillation, local hatchery release numbers, size at return, and regional and state salmon catch numbers. Jack survival and adult survival covaried strongly, suggesting the primary cause of mortality is encountered in the first four or five months of marine life. The number of hatchery fish had the strongest correlation with marine survival (r = 0.71), which could indicate that hatchery releases are prey for Auke Creek coho smolts or buffering these smolts from predators. Sea surface temperature was not significantly associated with adult survival, but was with jack survival. Surprisingly, scale growth was not correlated with marine survival. Adult size appears to be determined in the last year of marine life when the fish are in the Gulf of Alaska. Regional survival trends followed closely with Auke Creek marine survival, indicating factors affecting survival are regional in scope. Specific mechanisms were not defined, but the results indicate biological covariates were more associated with Auke Creek coho survival than were physical covariates"--Leaf iii.
Author: William G. Pearcy
Publisher: University of Washington Press
ISBN:
Category : Nature
Languages : en
Pages : 200
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Book Description
A compendium of Northeast Pacific salmon ecology, encompassing all five salmon and two trout species of Oncorhynchus--with Oregon coho salmon, the author's specialty for the past decade, acting as centerpiece. Annotation copyrighted by Book News, Inc., Portland, OR
