Age at Sexual Maturity, Sex Ratio, Fecundity, and Longevity of Isolated Headwater Populations of Westslope Cutthroat Trout

Downs, Christopher C.; White, Robert G.; Shepard, Bradley B.

doi:10.1577/1548-8675(1997)017<0085:aasmsr>2.3.co;2

Cited by 65 publications

(112 citation statements)

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“…At the smallest spatial scale, fish weight and time of year were identified as factors influencing habitat selection, and in general, body size (weight) is directly related to individual fitness. For example, a positive relationship between fecundity and fish size has been documented in salmonids (Bromage et al 1990;Downs et al 1997). In addition, habitat requirements that are necessary to survival in stream salmonids may differ according to fish size, with larger fish generally requiring deeper habitats to avoid predation (Schlosser 1987;Koehn et al 1994).…”

Section: Scale-dependent Pool Habitat Use By Troutmentioning

confidence: 99%

Scale‐Dependent Seasonal Pool Habitat Use by Sympatric Wild Brook Trout and Brown Trout Populations

Davis

Wagner

2016

Trans Am Fish Soc

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Sympatric populations of native Brook Trout Salvelinus fontinalis and naturalized Brown Trout Salmo trutta exist throughout the eastern USA. An understanding of habitat use by sympatric populations is of importance for fisheries management agencies because of the close association between habitat and population dynamics. Moreover, habitat use by stream‐dwelling salmonids may be further complicated by several factors, including the potential for fish to display scale‐dependent habitat use. Discrete‐choice models were used to (1) evaluate fall and early winter daytime habitat use by sympatric Brook Trout and Brown Trout populations based on available residual pool habitat within a stream network and (2) assess the sensitivity of inferred habitat use to changes in the spatial scale of the assumed available habitat. Trout exhibited an overall preference for pool habitats over nonpool habitats; however, the use of pools was nonlinear over time. Brook Trout displayed a greater preference for deep residual pool habitats than for shallow pool and nonpool habitats, whereas Brown Trout selected for all pool habitat categories similarly. Habitat use by both species was found to be scale dependent. At the smallest spatial scale (50 m), habitat use was primarily related to the time of year and fish weight. However, at larger spatial scales (250 and 450 m), habitat use varied over time according to the study stream in which a fish was located. Scale‐dependent relationships in seasonal habitat use by Brook Trout and Brown Trout highlight the importance of considering scale when attempting to make inferences about habitat use; fisheries managers may want to consider identifying the appropriate spatial scale when devising actions to restore and protect Brook Trout populations and their habitats.Received December 11, 2015; accepted March 2, 2016 Published online June 29, 2016

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Section: Scale-dependent Pool Habitat Use By Troutmentioning

confidence: 99%

Scale‐Dependent Seasonal Pool Habitat Use by Sympatric Wild Brook Trout and Brown Trout Populations

Davis

Wagner

2016

Trans Am Fish Soc

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“…Bonneville Cutthroat Trout that demonstrate fluvial migratory patterns are known to enter tributary streams in the spring to spawn and are typically larger than resident Bonneville Cutthroat Trout (Bernard and Israelsen 1982;Meyer et al 2003). Small fish (<150 mm) observed during our surveys likely represent mostly sexually immature fish (Downs et al 1997) and or "sneaker" activity (Gross 1991). It is unknown what proportion of the spawning fish comprised resident forms, but we assume there was a mixture of all size-classes; however, this is an area that requires further study.…”

Section: Spawning Activity On Reddsmentioning

confidence: 92%

Annual Variation of Spawning Cutthroat Trout in a Small Western USA Stream: A Case Study with Implications for the Conservation of Potamodromous Trout Life History Diversity

Bennett¹,

Al‐Chokhachy

Roper

et al. 2014

N American J Fish Manag

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Little is known about the variability in the spatial and temporal distribution of spawning potamodromous trout despite decades of research directed at salmonid spawning ecology and the increased awareness that conserving life history diversity should be a focus of management. We monitored a population of fluvial–resident Bonneville Cutthroat Trout Oncorhynchus clarkii utah in a tributary to the Logan River, Utah, from 2006 to 2012 to gain insight into the distribution and timing of spawning and what factors may influence these spawning activities. We monitored Bonneville Cutthroat Trout using redd surveys with multiple observers and georeferenced redd locations. We documented an extended spawning period that lasted from late April to mid‐July. The onset, median, and end of spawning was best predicted by the mean maximum water temperature during the first 13 weeks of the year (F = 130. 4, df = 5, R2 = 0.96, P < 0.0001) with spawning beginning and ending earlier in years that had warmer water temperatures prior to spawning. The distribution of redds was clumped each year and the relative density of redds was greater in a reach dominated by dams constructed by beavers Castor canadensis. Both dam failure and construction appeared to be responsible for creating new spawning habitat that was quickly occupied, demonstrating rapid temporal response to local habitat changes. Bonneville Cutthroat Trout appeared to establish and defend a redd for up to 2 d, and spawning most often occurred between similar‐sized individuals. Spawning surveys for potamodromous trout are an underutilized tool that could be used to better understand the distribution and timing of spawning as well as determine the size and trends of the reproducing portion of populations of management concern. Without efforts to document the diversity of this important aspect of potamodromous trout life history, prioritization of conservation will be problematic.

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“…The genotypes for each individual were initiated by randomly assigning allelic states across the initial populations following the sampled allele frequency distribution for each of the 16 loci and maximal alleles possible per locus with the k-allele mutation rate set to 0.0005. The initial sexratio for the entire population was 1.3 males per female [47]. Reproduction was set as heterosexual with a random mating structure within the populations that were separated by a barrier and mate selection chosen based on a male with replacement and a female with replacement.…”

Section: Criterion 1: Maintain Suitable Stream Habitats For Salmonid mentioning

confidence: 99%

“…Reproduction was set as heterosexual with a random mating structure within the populations that were separated by a barrier and mate selection chosen based on a male with replacement and a female with replacement. Each mated pair had a constant number of eggs of 287 and the sex assignment included a 43% change of being a female egg [47]. We did not allow for fluctuating population sizes and, therefore, every generation retained a constant number of individuals (i.e., lambda = 1 leading to an egg mortality of 99.2% with the remaining surviving eggs assumed to reach a reproducing adult age).…”

Section: Criterion 1: Maintain Suitable Stream Habitats For Salmonid mentioning

confidence: 99%

A Fine-scale Assessment of Using Barriers to Conserve Native Stream Salmonids: A Case Study in Akokala Creek, Glacier National Park, USA

Muhlfeld¹

2012

TOFISHSJ

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Abstract:Biologists are often faced with the difficult decision in managing native salmonids of where and when to install barriers as a conservation action to prevent upstream invasion of nonnative fishes. However, fine-scale approaches to assess long-term persistence of populations within streams and watersheds chosen for isolation management are often lacking. We employed a spatially-explicit approach to evaluate stream habitat conditions, relative abundance, and genetic diversity of native westslope cutthroat trout (Oncorhynchus clarkii lewisi) within the Akokala Creek watershed in Glacier National Park a population threatened by introgressive hybridization with nonnative rainbow trout (O. mykiss) from nearby sources. The systematic survey of 24 stream reaches showed broad overlap in fish population and suitable habitat characteristics among reaches and no natural barriers to fish migration were found. Analysis of population structure using 16 microsatellite loci showed modest amounts of genetic diversity among reaches, and that fish from Long Bow Creek were the only moderately distinct genetic group. We then used this information to assess the potential impacts of three barrier placement scenarios on long-term population persistence and genetic diversity. The two barrier placement scenarios in headwater areas generally failed to meet general persistence criteria for minimum population size (2,500 individuals, N e = 500), maintenance of long-term genetic diversity (H e ), and no population subdivision. Conversely, placing a barrier near the stream mouth and selectively passing non-hybridized, migratory spawners entering Akokala Creek met all persistence criteria and may offer the best option to conserve native trout populations and life history diversity. Systematic, fine-scale stream habitat, fish distribution, and genetic assessments in streams chosen for barrier installation are needed in conjunction with broader scale assessments to understand the potential impacts of using barriers for conservation of native salmonid populations threatened by nonnative fish invasions.

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Age at Sexual Maturity, Sex Ratio, Fecundity, and Longevity of Isolated Headwater Populations of Westslope Cutthroat Trout

Cited by 65 publications

References 13 publications

Scale‐Dependent Seasonal Pool Habitat Use by Sympatric Wild Brook Trout and Brown Trout Populations

Scale‐Dependent Seasonal Pool Habitat Use by Sympatric Wild Brook Trout and Brown Trout Populations

Annual Variation of Spawning Cutthroat Trout in a Small Western USA Stream: A Case Study with Implications for the Conservation of Potamodromous Trout Life History Diversity

A Fine-scale Assessment of Using Barriers to Conserve Native Stream Salmonids: A Case Study in Akokala Creek, Glacier National Park, USA

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