Age, Growth, and Life History of Steelhead Rainbow Trout (Oncorhynchus Mykiss) in the Lower Yuba River, California PDF Download
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Author: William T. Mitchell
Publisher:
ISBN:
Category : Rainbow trout
Languages : en
Pages : 0
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Author: William T. Mitchell
Publisher:
ISBN:
Category : Rainbow trout
Languages : en
Pages : 0
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Author: James S. Hopelain
Publisher:
ISBN:
Category : Fish populations
Languages : en
Pages : 26
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Author: Cynthia Collin
Publisher:
ISBN:
Category : Fishes
Languages : en
Pages : 126
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This study characterized age and length at spawning, age and length at smolting, and range and frequency of adult sizes of the Big Sur River steelhead population.
Author: Jeffrey F. Kozlowski
Publisher:
ISBN:
Category :
Languages : en
Pages : 178
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Author: Leo Shapovalov
Publisher:
ISBN:
Category : Coho salmon
Languages : en
Pages : 402
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Author: Trey Combs
Publisher:
ISBN:
Category : Rainbow trout
Languages : en
Pages : 202
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Author: Jeffrey Lehn Gidley
Publisher:
ISBN:
Category : Steelhead (Fish)
Languages : en
Pages : 54
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Author: Christian E. Zimmerman
Publisher:
ISBN:
Category : Steelhead (Fish)
Languages : en
Pages : 232
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Sympatric steelhead and resident rainbow trout (Oncorhynchus mykiss) are known to exist in many rivers throughout the Pacific Rim. Whether sympatric steelhead and resident rainbow trout are polymorphisms within a single gene pool or two reproductively isolated populations has significant implications concerning the study and conservation of this polytypic species. I examined population structure and use of spawning and rearing habitats by steelhead and resident rainbow trout in the Deschutes River, Oregon. I used otolith microchemistry to determine the maternal origin (steelhead verses resident) of adult steelhead and resident rainbow trout based on Sr/Ca ratios in primordia and freshwater growth regions of otoliths. Only steelhead of steelhead origin and resident rainbow trout of resident origin were encountered. In the Babine River of British Columbia, however, steelhead of resident origin and resident rainbow trout of steelhead origin were present. Temporal and spatial segregation of spawning habitat served to limit breeding between steelhead and resident rainbow trout in the mainstem Deschutes River. The timing of 50% spawning by steelhead occurred 9 to 10 weeks earlier than by resident rainbow trout. Steelhead spawning sites were deeper and of larger substrate than those used by resident rainbow trout. There was an overlap in the timing of emergence by steelhead and resident rainbow trout fry in the mainstem Deschutes River, but higher levels of aggression and territoriality characterize newly emerged steelhead fry. Determination of maternal origin based on otolith microchemistry indicated that young-of- year 0. mykiss in small hydrologically unstable tributaries to the Deschutes River were exclusively the progeny of steelhead. Progeny of resident rainbow trout numerically dominated mainstem-rearing habitats. Based on the degree of segregation between steelhead and resident rainbow trout, the two life history forms act as two separate species in the Deschutes River. This relationship has significant implications concerning the restoration and conservation of steelhead and resident rainbow trout. Where steelhead and resident rainbow trout constitute reproductively isolated populations, conservation of both life history forms within the species cannot be achieved unless both populations are maintained.
Author: Jamie N. Thompson
Publisher:
ISBN:
Category : Bioenergetics
Languages : en
Pages : 93
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Wild Steelhead Trout, Oncorhynchus mykiss, in the Puget Sound are currently in decline, and very little is known about the early life history of these threatened fish. This study evaluated consequences of early life growth in terms of survival to smolt or adult stages. The objectives of this study were to determine whether significant size-selective mortality (SSM) in Steelhead could be detected between freshwater stages and returning adults; and if so, how the magnitude of size selectivity varied among reaches categorized by three different precipitation zones (snow, mixed rain-snow, or rain). Wild Steelhead in the Skagit River basin were sampled as juveniles, smolts, and adults, and scales were measured to compare back-calculated freshwater growth rates and size distributions of rearing juveniles with individuals that survived from an earlier life stage to the smolt and adult stages. Linear regression of scale radius (SR) and fork length indicated that SR was a reasonable predictor of fork length during freshwater residency. Back-calculated size-at-annulus estimates indicated that fish sampled as adults grew significantly faster to age 1, 2, and 3 annuli compared to fish sampled as juveniles, and faster to the age 2 and 3 annuli compared to fish sampled as smolts. Within precipitation zones, fish sampled as juveniles were consistently smaller at each freshwater annulus compared to those same freshwater annuli on fish sampled as adults. An increased disparity in size-at-annuli 2 and 3 between fish sampled as juveniles, smolts, and adults suggests that fast growth during the period at which Steelhead smoltify is vitally important to survival to adulthood. These findings provide evidence that survival among life stages is an important dynamic in wild Steelhead, and can be attributed, in part, to size attained at earlier life stages. Efforts for recovery of threatened Puget Sound Steelhead could benefit by considering growth- and size-selective mortality in freshwater environments, and identifying factors that limit early life growth at a finer scale of habitat, for example among sub-basins or precipitation zones.
Author: Gordon S. Becker
Publisher:
ISBN:
Category : Rainbow trout
Languages : en
Pages : 448
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