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Virginia Tech
1.
Henebry, Michael Lee.
Biological and Ecological Trait Associations and Analysis of Spatial and Intraspecific Variation in Fish Traits.
Degree: MS, Fisheries and Wildlife Sciences, 2011, Virginia Tech
URL: http://hdl.handle.net/10919/33894 
► Traits provide an informative approach to examine species-environment interactions. Often, species-by-species approaches are inefficient to generate generalizable ecological relationships and do not predict species responses…
(more)
▼ Traits provide an informative approach to examine species-environment interactions. Often, species-by-species approaches are inefficient to generate generalizable ecological relationships and do not predict species responses to environmental changes based on specific traits species possess. Multiple lines of inquiry and multi-scale approaches are best for assessing environment-trait responses. This thesis examines important questions not specifically addressed before in traits-based research. Chapter one explores biological and ecological trait associations incorporating ontogenetic diet shifts for New River fishes. Niche shift analysis as a chapter one sub-objective quantitatively support where species-specific diet shifts likely occur. Strong biological-ecological trait associations, some intuitive and others not so intuitive, were found that relate biological structure to ecological function. Improved understanding of trait associations, including what factors influence others, supports inference of ecology of fishes. Chapters two and three examine spatial and intraspecific trait variability. Chapter two specifically examines large-scale life history trait variability along latitudinal gradients for twelve widely distributed fish species, including directionality of trait variation, and hypothesizing how optimal traits change with large-scale environmental factors. Strong positive and negative patterns found include average total length of newly hatched larvae, average total length at maturation, average spawning temperature, average egg diameter, and maximum length. These five traits are correlated with other adaptive attributes (i.e. growth rate, reproductive output, and longevity/population turnover rate). In contrast to latitudinal scale, Chapter three examines trait variability of white sucker (Catostomus commersonii) and fantail darter (Etheostoma flabellare) as a function of small-watershed scale spatial factors and anthropogenic disturbance. Toms Creek and Chestnut Creek white sucker and fantail darter displayed positive response to disturbance, contrary to past studies. Lower resource competition, and / or competitive exclusion of fishes with similar niche requirements are possible mechanisms. All three objectives support understanding of trait association and variability as a useful foundation in ecological applications and for formulating plans for conservation and management of species.
Advisors/Committee Members: Frimpong, Emmanuel A. (committeechair), Murphy, Brian R. (committee member), Orth, Donald J. (committee member).
Subjects/Keywords: biological trait; ecological trait; trait associations; large-scale latitudinal variation; latitudinal directionality; bioassessment
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APA (6th Edition):
Henebry, M. L. (2011). Biological and Ecological Trait Associations and Analysis of Spatial and Intraspecific Variation in Fish Traits. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/33894
Chicago Manual of Style (16th Edition):
Henebry, Michael Lee. “Biological and Ecological Trait Associations and Analysis of Spatial and Intraspecific Variation in Fish Traits.” 2011. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/33894.
MLA Handbook (7th Edition):
Henebry, Michael Lee. “Biological and Ecological Trait Associations and Analysis of Spatial and Intraspecific Variation in Fish Traits.” 2011. Web. 17 Jan 2021.
Vancouver:
Henebry ML. Biological and Ecological Trait Associations and Analysis of Spatial and Intraspecific Variation in Fish Traits. [Internet] [Masters thesis]. Virginia Tech; 2011. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/33894.
Council of Science Editors:
Henebry ML. Biological and Ecological Trait Associations and Analysis of Spatial and Intraspecific Variation in Fish Traits. [Masters Thesis]. Virginia Tech; 2011. Available from: http://hdl.handle.net/10919/33894
Virginia Tech
2.
Olsen, Jesse Eric Burle.
Flood pulse influences on exploited fish populations of the Central Amazon.
Degree: MS, Fisheries and Wildlife Sciences, 2017, Virginia Tech
URL: http://hdl.handle.net/10919/83864
► Seasonally fluctuating water levels, known as flood pulses, influence the population dynamics and catches of fishes from river-floodplains. Although different measures of flood pulses, here…
(more)
▼ Seasonally fluctuating water levels, known as flood pulses, influence the population dynamics and catches of fishes from river-floodplains. Although different measures of flood pulses, here called flood pulse variables, have been correlated to changes in catches of river-floodplain fishes, the flood pulse variables that have the strongest relationships to catches have not been identified. Furthermore, it is unclear if flood pulses influence catches of river-floodplain fishes with different life history strategies in different ways. Catches of 21 taxa from approximately 18,000 fishing trips were modeled as a function of fishing effort, gear type, seasonal flood pulse variables, and interannual flood pulse variables. These models were analyzed to understand which flood pulse variables had the strongest relationships to catches, and evaluate different flood pulse influences among taxa with different life history strategies. High water flood pulse variables generally had positive influences on catches in future years, while low water flood pulse variables generally had negative influences on catches in future years. Flood pulses generally had stronger influences on the catches of fishes with high fecundities and smaller eggs than on catches of fishes with low fecundities and larger eggs. Variation was observed in strengths and directions of flood pulse influences on catches of fishes with similar and different life history strategies. While my results were generally consistent with prevailing knowledge of how flood pulses influence catches of fishes, other biological factors of specific fish populations may further explain population responses to flood pulses.
Advisors/Committee Members: Castello, Leandro (committeechair), Jiao, Yan (committee member), Orth, Donald J. (committee member).
Subjects/Keywords: Multispecies fisheries; flood pulse; modeling; floodplain ecology; LASSO
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APA (6th Edition):
Olsen, J. E. B. (2017). Flood pulse influences on exploited fish populations of the Central Amazon. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/83864
Chicago Manual of Style (16th Edition):
Olsen, Jesse Eric Burle. “Flood pulse influences on exploited fish populations of the Central Amazon.” 2017. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/83864.
MLA Handbook (7th Edition):
Olsen, Jesse Eric Burle. “Flood pulse influences on exploited fish populations of the Central Amazon.” 2017. Web. 17 Jan 2021.
Vancouver:
Olsen JEB. Flood pulse influences on exploited fish populations of the Central Amazon. [Internet] [Masters thesis]. Virginia Tech; 2017. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/83864.
Council of Science Editors:
Olsen JEB. Flood pulse influences on exploited fish populations of the Central Amazon. [Masters Thesis]. Virginia Tech; 2017. Available from: http://hdl.handle.net/10919/83864
Virginia Tech
3.
Ballesta Artero, Irene Maria.
Influence of the Estimator Selection in Scalloped Hammerhead Shark Stock Assessment.
Degree: MS, Fisheries and Wildlife Sciences, 2014, Virginia Tech
URL: http://hdl.handle.net/10919/24819
► In natural sciences, frequentist paradigm has led statistical practice; however, Bayesian approach has been gaining strength in the last decades. Our study assessed the scalloped…
(more)
▼ In natural sciences, frequentist paradigm has led statistical practice; however, Bayesian approach has been gaining strength in the last decades. Our study assessed the scalloped hammerhead shark population on the western North Atlantic Ocean using Bayesian methods. This approach allowed incorporate diverse types of errors in the surplus production model and compare the influences of different statistical estimators on the values of the key parameters (r, growth rate; K carrying capacity; depletion, FMSY , fishing levels that would sustain maximum yield; and NMSY, abundance at maximum sustainable yield). Furthermore, we considered multi-levelpriors due to the variety of results on the population growth rate of this species. Our research showed that estimator selection influences the results of the surplus production model and therefore, the value of the target management points. Based on key parameter estimates with uncertainty and Deviance Information Criterion, we suggest that state-space Bayesian models be used for assessing scalloped hammerhead shark or other fish stocks with poor data available. This study found the population was overfished and suffering overfishing. Therefore, based on our research and that there was very low evidence of recovery according with the last data available, we suggest prohibition of fishing for this species because: (1) it is highly depleted (14% of its initial population), (2) the fishery status is very unstable over time, (3) it has a low reproductive rate contributing to a higher risk of overexploitation, and (4) the easiness of misidentification among different hammerhead sharks (smooth, great, scalloped and cryptic species).
Advisors/Committee Members: Jiao, Yan (committeechair), Orth, Donald J. (committee member), Siegried, Kate Andrews (committee member).
Subjects/Keywords: Sphyrna lewini; logistic production model; types of error; likelihood; Bayesian approach
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APA (6th Edition):
Ballesta Artero, I. M. (2014). Influence of the Estimator Selection in Scalloped Hammerhead Shark Stock Assessment. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/24819
Chicago Manual of Style (16th Edition):
Ballesta Artero, Irene Maria. “Influence of the Estimator Selection in Scalloped Hammerhead Shark Stock Assessment.” 2014. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/24819.
MLA Handbook (7th Edition):
Ballesta Artero, Irene Maria. “Influence of the Estimator Selection in Scalloped Hammerhead Shark Stock Assessment.” 2014. Web. 17 Jan 2021.
Vancouver:
Ballesta Artero IM. Influence of the Estimator Selection in Scalloped Hammerhead Shark Stock Assessment. [Internet] [Masters thesis]. Virginia Tech; 2014. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/24819.
Council of Science Editors:
Ballesta Artero IM. Influence of the Estimator Selection in Scalloped Hammerhead Shark Stock Assessment. [Masters Thesis]. Virginia Tech; 2014. Available from: http://hdl.handle.net/10919/24819
Virginia Tech
4.
Richard, Jordan Conner.
Human and environmental influences on the distribution and abundance of arapaima in river floodplains of the Lower Amazon.
Degree: MS, Fisheries and Wildlife Sciences, 2016, Virginia Tech
URL: http://hdl.handle.net/10919/73479
► Understanding the factors influencing the abundance and distribution of tropical floodplain fishes is an important component of fisheries management plans to support future sustainable resource…
(more)
▼ Understanding the factors influencing the abundance and distribution of tropical floodplain fishes is an important component of fisheries management plans to support future sustainable resource use. This thesis uses a multi-scale approach to understand the habitat factors controlling the distribution and abundance of arapaima (Arapaima spp.) in river floodplains of the lower Amazon River, near the municipality of Santarém, Para State, Brazil. In chapter 1, a study of eight environmental variables in 13 dry season floodplain lakes demonstrates that lake depth, relative depth, conductivity, and transparency were significantly related to the probability of arapaima presence at individual locations within lakes. Further, the study revealed that smaller arapaima were more likely to be found near macrophyte coverage than in open water locations. In chapter 2, a landscape scale approach was used to examine the interactions between management systems, landscape habitat coverage, and spatial arrangement on arapaima population sizes in 73 floodplain lakes. Results showed that all three influences were important in explaining variability in arapaima abundances. Management and habitat variables contributed equally in controlling arapaima abundances. Both had strong patterns of spatial arrangement and overlapped significantly, suggesting that analysis of either management systems or landscape habitats without the other would lead to overestimations of the strength of their influence. Findings from both chapters support the notion that future sustainable use of arapaima populations requires a dualistic approach combining habitat conservation with fisheries management techniques enacted at a local scale.
Advisors/Committee Members: Castello, Leandro (committeechair), Angermeier, Paul L. (committee member), Orth, Donald J. (committee member).
Subjects/Keywords: arapaima; river floodplain; social ecological systems; habitat use
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APA (6th Edition):
Richard, J. C. (2016). Human and environmental influences on the distribution and abundance of arapaima in river floodplains of the Lower Amazon. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/73479
Chicago Manual of Style (16th Edition):
Richard, Jordan Conner. “Human and environmental influences on the distribution and abundance of arapaima in river floodplains of the Lower Amazon.” 2016. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/73479.
MLA Handbook (7th Edition):
Richard, Jordan Conner. “Human and environmental influences on the distribution and abundance of arapaima in river floodplains of the Lower Amazon.” 2016. Web. 17 Jan 2021.
Vancouver:
Richard JC. Human and environmental influences on the distribution and abundance of arapaima in river floodplains of the Lower Amazon. [Internet] [Masters thesis]. Virginia Tech; 2016. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/73479.
Council of Science Editors:
Richard JC. Human and environmental influences on the distribution and abundance of arapaima in river floodplains of the Lower Amazon. [Masters Thesis]. Virginia Tech; 2016. Available from: http://hdl.handle.net/10919/73479
Virginia Tech
5.
Floyd Jr, Stephen Preston.
Cheating and Selfishness in Reproductive Interactions among Nest Associative Cyprinids.
Degree: MS, Fisheries and Wildlife Sciences, 2016, Virginia Tech
URL: http://hdl.handle.net/10919/80977
► Mutualism is an understudied interaction in ecosystems throughout the world. Within the eastern United States, one fish-fish mutualism is the nest association between Nocomis and…
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▼ Mutualism is an understudied interaction in ecosystems throughout the world. Within the eastern United States, one fish-fish mutualism is the nest association between Nocomis and other cyprinids. I assessed the role of host parental care while testing for the selfish-herd effect. Additionally, I examined multiple nest associates in order to elucidate potential cheaters. I utilized gonadosomatic index (GSI) to compare reproductive condition among the bluehead chub Nocomis leptocephalus and its putative nest associates in Catawba Creek,
Virginia. GSI of potentially obligate associates tracked host GSI more closely than weak associates, while weak associates spawned prior to Nocomis spawning. Given their GSI patterns and behavior, central stonerollers Campostoma anomalum may be cheaters in the interaction. I used multiple experiments to test for the selfish-herd effect, the role of parental care, and how relative risk influences reproductive decisions of associates. Most eggs were located in the bottom upstream quarter of nests, and a molecular analysis revealed that stonerollers and chubs constituted the majority of identified individuals. A comparison of host-associate ratios from four nest sections failed to identify the selfish herd effect. Another experiment found that host egg covering significantly reduced egg predation. Lastly, I assessed relative egg predation risk at four potential spawning locations; predation levels did not differ significantly at any location. While GSI patterns suggest that stonerollers may be cheaters, genetic evidence indicates that stonerollers spawn on Nocomis nests. Because GSI does not completely assess reproduction, secondary stoneroller reproduction on Nocomis nests may have been overlooked.
Advisors/Committee Members: Frimpong, Emmanuel A. (committeechair), Orth, Donald J. (committee member), Angermeier, Paul L. (committee member).
Subjects/Keywords: Nocomis; Mutualism; Nest Association; Gonadosomatic Index; Parental Care; Selfish Herd Effect; Cheating
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APA (6th Edition):
Floyd Jr, S. P. (2016). Cheating and Selfishness in Reproductive Interactions among Nest Associative Cyprinids. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/80977
Chicago Manual of Style (16th Edition):
Floyd Jr, Stephen Preston. “Cheating and Selfishness in Reproductive Interactions among Nest Associative Cyprinids.” 2016. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/80977.
MLA Handbook (7th Edition):
Floyd Jr, Stephen Preston. “Cheating and Selfishness in Reproductive Interactions among Nest Associative Cyprinids.” 2016. Web. 17 Jan 2021.
Vancouver:
Floyd Jr SP. Cheating and Selfishness in Reproductive Interactions among Nest Associative Cyprinids. [Internet] [Masters thesis]. Virginia Tech; 2016. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/80977.
Council of Science Editors:
Floyd Jr SP. Cheating and Selfishness in Reproductive Interactions among Nest Associative Cyprinids. [Masters Thesis]. Virginia Tech; 2016. Available from: http://hdl.handle.net/10919/80977
Virginia Tech
6.
Moore, Michael James.
Distribution and Population Characterization of Clinch Dace (Chrosomus sp. cf. saylori) in the Upper Clinch River System, Virginia.
Degree: MS, Fisheries and Wildlife Sciences, 2016, Virginia Tech
URL: http://hdl.handle.net/10919/71294
► The Clinch Dace Chrosomus sp. cf. saylori is a species of minnow known from only two counties in Virginia. Prior surveys established the species' presence…
(more)
▼ The Clinch Dace Chrosomus sp. cf. saylori is a species of minnow known from only two counties in
Virginia. Prior surveys established the species' presence in just eight tributaries to the upper Clinch River. A management plan, which should include both population monitoring and habitat restoration, is still lacking for the species. Population monitoring must balance high detection probability with low risk of injury to captured individuals. I sampled 98 sites in 2014 and 2015 within the putative range of Clinch Dace to refine estimates of its distribution. I sampled 70 of the 98 sites with multiple gears and replication in an occupancy modeling framework. Clinch Dace occupied low-gradient headwater streams with relatively low conductivity in forested watersheds. My surveys uncovered two new tributaries occupied by Clinch Dace, and I was unable to find Clinch Dace in two historically occupied streams. Species detection probability was higher with backpack electrofishing than minnow trapping. N-mixture models suggest that Clinch Dace are more abundant in watersheds with high forest cover although forest cover is highly correlated spatially in the nested stream network. Density estimates from mark-recapture sampling suggest that Clinch Dace occur at low densities in approximately 31.5 km of headwater streams. The mean estimate of global population size was 6,706 individuals. Some populations could be affected by low genetic diversity. I conclude by developing a prioritization framework for restoration and protection of 15 candidate conservation areas. Managers should work with private landowners to implement best management practices in high priority watersheds.
Advisors/Committee Members: Orth, Donald J. (committeechair), Frimpong, Emmanuel A. (committee member), Hallerman, Eric M. (committee member).
Subjects/Keywords: species distribution; habitat associations; conservation; planning
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APA (6th Edition):
Moore, M. J. (2016). Distribution and Population Characterization of Clinch Dace (Chrosomus sp. cf. saylori) in the Upper Clinch River System, Virginia. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/71294
Chicago Manual of Style (16th Edition):
Moore, Michael James. “Distribution and Population Characterization of Clinch Dace (Chrosomus sp. cf. saylori) in the Upper Clinch River System, Virginia.” 2016. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/71294.
MLA Handbook (7th Edition):
Moore, Michael James. “Distribution and Population Characterization of Clinch Dace (Chrosomus sp. cf. saylori) in the Upper Clinch River System, Virginia.” 2016. Web. 17 Jan 2021.
Vancouver:
Moore MJ. Distribution and Population Characterization of Clinch Dace (Chrosomus sp. cf. saylori) in the Upper Clinch River System, Virginia. [Internet] [Masters thesis]. Virginia Tech; 2016. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/71294.
Council of Science Editors:
Moore MJ. Distribution and Population Characterization of Clinch Dace (Chrosomus sp. cf. saylori) in the Upper Clinch River System, Virginia. [Masters Thesis]. Virginia Tech; 2016. Available from: http://hdl.handle.net/10919/71294
Virginia Tech
7.
Harris, Sheila Catherine.
Genetic Marker-Assisted Management of Virginia Sport Fishes.
Degree: MS, Fisheries and Wildlife Science, 2020, Virginia Tech
URL: http://hdl.handle.net/10919/98505
► Population genetics have proven useful for defining the most appropriate units for conservational management across a variety of species. Molecular genetic markers can be used…
(more)
▼ Population genetics have proven useful for defining the most appropriate units for conservational management across a variety of species. Molecular genetic markers can be used to assess genetic diversity, assign parentage, quantify inbreeding, and demonstrate structuring of populations across a system. Striped Bass Morone saxatilis and Walleye Sander vitreus are both widely sought gamefishes in the Commonwealth of
Virginia. I applied population genetic approaches to recognize genetically distinct groups of populations and to recommend genetically cognizant management practices. Striped Bass across the Atlantic Coast and in the Roanoke River drainage exhibit low genetic variation. After screening variation at 12 DNA markers, I found that Striped Bass are differentiated between landlocked and migratory populations, which need to be managed separately. Within stocked populations in the Roanoke River basin, there have been impacts stemming from propagation of small numbers of broodstock, and propagation and stocking practices will need to be changed to reduce apparent inbreeding depression. Walleye populations across the eastern native range were screened to better understand evolutionary history and to seek new marker alleles for the native upper New River population. After screening genetic variation at eight DNA marker loci, I identified four evolutionarily distinct stocks of Walleye across eastern North America. Although I did not identify new marker alleles for native upper New River native Walleye, I showed that marker-assisted selection has increased the frequencies of existing marker alleles over the past twenty years. The results of this project can contribute to better fishery management strategies for both of these important gamefish species.
Advisors/Committee Members: Hallerman, Eric M. (committeechair), Frimpong, Emmanuel A. (committee member), Orth, Donald J. (committee member).
Subjects/Keywords: Striped Bass; Walleye; population genetics; marker-assisted selection; fishery management
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APA (6th Edition):
Harris, S. C. (2020). Genetic Marker-Assisted Management of Virginia Sport Fishes. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/98505
Chicago Manual of Style (16th Edition):
Harris, Sheila Catherine. “Genetic Marker-Assisted Management of Virginia Sport Fishes.” 2020. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/98505.
MLA Handbook (7th Edition):
Harris, Sheila Catherine. “Genetic Marker-Assisted Management of Virginia Sport Fishes.” 2020. Web. 17 Jan 2021.
Vancouver:
Harris SC. Genetic Marker-Assisted Management of Virginia Sport Fishes. [Internet] [Masters thesis]. Virginia Tech; 2020. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/98505.
Council of Science Editors:
Harris SC. Genetic Marker-Assisted Management of Virginia Sport Fishes. [Masters Thesis]. Virginia Tech; 2020. Available from: http://hdl.handle.net/10919/98505
Virginia Tech
8.
White, Shannon Lynn.
Distribution and Life History of Chrosomus sp. cf. saylori in the Upper Clinch River Watershed, Virginia.
Degree: MS, Fisheries and Wildlife Sciences, 2012, Virginia Tech
URL: http://hdl.handle.net/10919/19200
► In 1999, a new species of minnow, Chrosomus sp. cf. saylori (Clinch dace), was discovered in the Tennessee drainage of Virginia. Chrosomus sp. cf. saylori…
(more)
▼ In 1999, a new species of minnow, Chrosomus sp. cf. saylori (Clinch dace), was discovered in the Tennessee drainage of
Virginia. Chrosomus sp. cf. saylori are listed as a Federal Species of Concern and on
Virginia\'s Wildlife Action Plan as Tier II- Very High Conservation Need because of potential threats from habitat degradation, high population fragmentation, and a largely unknown distribution. Consequently, a management plan for C. sp. cf. saylori is of utmost importance, but more information regarding its distribution and life history is required before such a plan can be implemented. In 2011 and 2012 I sampled 60 headwater streams in the upper Clinch River watershed,
Virginia. From this and historical data, I conclude that C. sp. cf. saylori are restricted to eight small tributaries to the Clinch River. Multivariate analysis of habitat correlates indicated that C. sp. cf. saylori populations are found in small, high elevation streams with gravel substrate and forested watersheds. Three species distribution models were unable to predict C. sp. cf. saylori distribution. Morphological traits were significantly different between C. sp. cf. saylori and other Chrosomus, thereby providing an initial indication of speciation and differing niche roles. I observed a nest association with Campostoma anomalum. Gonad weight was lower for C. sp. cf. saylori than closely-related congeners. Together, this information indicates that C. sp. cf. saylori are narrowly distributed and populations are small, fragmented, and of questionable viability. In the future, long-term monitoring efforts and genetics analyses should be completed and additional protection measures pursued.
Advisors/Committee Members: Orth, Donald J. (committeechair), Dolloff, C. Andrew (committee member), Frimpong, Emmanuel A. (committee member).
Subjects/Keywords: Chrosomus sp. cf. saylori; species distribution; reproductive biology; life history
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APA (6th Edition):
White, S. L. (2012). Distribution and Life History of Chrosomus sp. cf. saylori in the Upper Clinch River Watershed, Virginia. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/19200
Chicago Manual of Style (16th Edition):
White, Shannon Lynn. “Distribution and Life History of Chrosomus sp. cf. saylori in the Upper Clinch River Watershed, Virginia.” 2012. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/19200.
MLA Handbook (7th Edition):
White, Shannon Lynn. “Distribution and Life History of Chrosomus sp. cf. saylori in the Upper Clinch River Watershed, Virginia.” 2012. Web. 17 Jan 2021.
Vancouver:
White SL. Distribution and Life History of Chrosomus sp. cf. saylori in the Upper Clinch River Watershed, Virginia. [Internet] [Masters thesis]. Virginia Tech; 2012. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/19200.
Council of Science Editors:
White SL. Distribution and Life History of Chrosomus sp. cf. saylori in the Upper Clinch River Watershed, Virginia. [Masters Thesis]. Virginia Tech; 2012. Available from: http://hdl.handle.net/10919/19200
Virginia Tech
9.
Bourquin, Rebecca May.
Population Fragmentation and Genetic Diversity of Chrosomus sp. cf. saylori (Clinch Dace).
Degree: MS, Fisheries and Wildlife Science, 2020, Virginia Tech
URL: http://hdl.handle.net/10919/96757
► The Clinch Dace is a small, threatened minnow in the Clinch River basin that was unknown until 1999. Since then, research has addressed the biology,…
(more)
▼ The Clinch Dace is a small, threatened minnow in the Clinch River basin that was unknown until 1999. Since then, research has addressed the biology, life history, and distribution of this fish. This study used data from selectively neutral genetic markers to analyze the population structure and degree of differentiation of Clinch Dace populations. My study sites were targeted at road crossings near known Clinch Dace populations to assess the effect of habitat fragmentation on Clinch Dace populations and to maximize the likelihood that I would collect enough genetic material for analysis. Genetic analyses showed that while there is some admixture among certain populations of Clinch Dace, there is differentiation at neutral genetic markers. This differentiation does not necessarily indicate adaptive variation among populations which could result in outbreeding depression should populations be mixed through translocations, but it is reason to proceed with caution. Road crossings were generally not found to be a cause of further population fragmentation in Clinch Dace, as demonstrated by genetic analysis and statistical analysis. Almost all of the occupied road crossing sites in this study were either embedded, free-flowing culverts that were not perched or small bridges, and these were not deemed to be obvious barriers to fish movement. The only exception was Hart Creek 2, where the culvert is slightly perched and Fst is high between populations in the upstream and downstream reaches. The results of this study will help to inform managers as to what conservation actions can be taken to improve population viability. One potential management action from this study could be the retrofitting of culverts that have become perched and are acting as barriers to Clinch Dace movement. Another potential conservation strategy is to translocate individuals from large population to small populations. The study determined: 1) which translocations might be acceptable based on the degree of genetic differentiation among populations, and 2) identified potential donor and receiving streams for translocations.
Advisors/Committee Members: Orth, Donald J. (committeechair), Stauffer, Dean F. (committee member), Hallerman, Eric M. (committee member).
Subjects/Keywords: Clinch Dace; fragmentation; genetic differentiation; road crossings
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APA (6th Edition):
Bourquin, R. M. (2020). Population Fragmentation and Genetic Diversity of Chrosomus sp. cf. saylori (Clinch Dace). (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/96757
Chicago Manual of Style (16th Edition):
Bourquin, Rebecca May. “Population Fragmentation and Genetic Diversity of Chrosomus sp. cf. saylori (Clinch Dace).” 2020. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/96757.
MLA Handbook (7th Edition):
Bourquin, Rebecca May. “Population Fragmentation and Genetic Diversity of Chrosomus sp. cf. saylori (Clinch Dace).” 2020. Web. 17 Jan 2021.
Vancouver:
Bourquin RM. Population Fragmentation and Genetic Diversity of Chrosomus sp. cf. saylori (Clinch Dace). [Internet] [Masters thesis]. Virginia Tech; 2020. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/96757.
Council of Science Editors:
Bourquin RM. Population Fragmentation and Genetic Diversity of Chrosomus sp. cf. saylori (Clinch Dace). [Masters Thesis]. Virginia Tech; 2020. Available from: http://hdl.handle.net/10919/96757
10.
Stokes, Gretchen Louise.
Air-breathing and movement ecology of Arapaima sp. in the Amazon.
Degree: MS, Fisheries and Wildlife Sciences, 2017, Virginia Tech
URL: http://hdl.handle.net/10919/84350
► The annual hydrological cycle of floodplains supports fishes that are uniquely adapted to optimize resources throughout the year. Such adaptations to changing environments include air-breathing…
(more)
▼ The annual hydrological cycle of floodplains supports fishes that are uniquely adapted to optimize resources throughout the year. Such adaptations to changing environments include air-breathing for seasonally hypoxic waters and directed movements to best utilize habitats as they become available. This study examined the environmental, temporal and body-size influences on air-breathing behavior and movement ecology of Arapaima sp., one of the most economically and ecologically significant species in the Amazon. Acoustic (n=15) and radio (n=12) telemetry was used to study the influences on air-breathing and movement ecology of arapaima in the Central Amazon. Generalized additive mixed models showed that temperature was the most influential predictor of air-breathing intervals, followed by body size. The shortest breathing intervals were associated with consecutive "aggressive" breaths while the longest breathing intervals had consecutive "calm" breaths. Generalized linear mixed models showed that flood stage was the most important predictor of residency time, directional movement, and rate of movement. Fish moved faster in the flood and dry stages than the rising and falling stages, and spent longer in one place in the rising and falling stages than the flood and dry stages. Findings of this study may be used to inform management decisions for arapaima conservation, such as protected habitat and population counts, with applications to fishes across river-floodplain ecosystems globally.
Advisors/Committee Members: Castello, Leandro (committeechair), Martins, Eduardo (committee member), Orth, Donald J. (committee member).
Subjects/Keywords: Air-breathing fishes; river-floodplains; Amazon; arapaima; movement ecology; telemetry
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APA (6th Edition):
Stokes, G. L. (2017). Air-breathing and movement ecology of Arapaima sp. in the Amazon. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/84350
Chicago Manual of Style (16th Edition):
Stokes, Gretchen Louise. “Air-breathing and movement ecology of Arapaima sp. in the Amazon.” 2017. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/84350.
MLA Handbook (7th Edition):
Stokes, Gretchen Louise. “Air-breathing and movement ecology of Arapaima sp. in the Amazon.” 2017. Web. 17 Jan 2021.
Vancouver:
Stokes GL. Air-breathing and movement ecology of Arapaima sp. in the Amazon. [Internet] [Masters thesis]. Virginia Tech; 2017. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/84350.
Council of Science Editors:
Stokes GL. Air-breathing and movement ecology of Arapaima sp. in the Amazon. [Masters Thesis]. Virginia Tech; 2017. Available from: http://hdl.handle.net/10919/84350
Virginia Tech
11.
Vadas, Robert L.
Habitat tools for assessing instream-flow needs for fishes in the upper Roanoke River, Virginia.
Degree: PhD, Fisheries and Wildlife Sciences, 1994, Virginia Tech
URL: http://hdl.handle.net/10919/28250
► The goal of this research was to formulate new tools for instream-flow analyses, with emphasis on protecting fish assemblages in speciose, warmer-water streams. This included…
(more)
▼ The goal of this research was to formulate new tools for instream-flow analyses, with emphasis on protecting fish assemblages in speciose, warmer-water streams. This included habitat and fish data sets for the upper Roanoke River (URR) in southwestern
Virginia, collected during the warmer, low- f low seasons of 1989-1991. Physical data were collected in small, rectangular quadrats or crosssectional transacts, whereas fish were collected by seining and electroshocking in the quadrats. Statistical analyses included uni-, bi-, and multivariate analyses.
Advisors/Committee Members: Orth, Donald J. (committeechair).
Subjects/Keywords: Fish habitat improvement Roanoke River (Va. and N.; LD5655.V856 1994.V333
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APA (6th Edition):
Vadas, R. L. (1994). Habitat tools for assessing instream-flow needs for fishes in the upper Roanoke River, Virginia. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/28250
Chicago Manual of Style (16th Edition):
Vadas, Robert L. “Habitat tools for assessing instream-flow needs for fishes in the upper Roanoke River, Virginia.” 1994. Doctoral Dissertation, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/28250.
MLA Handbook (7th Edition):
Vadas, Robert L. “Habitat tools for assessing instream-flow needs for fishes in the upper Roanoke River, Virginia.” 1994. Web. 17 Jan 2021.
Vancouver:
Vadas RL. Habitat tools for assessing instream-flow needs for fishes in the upper Roanoke River, Virginia. [Internet] [Doctoral dissertation]. Virginia Tech; 1994. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/28250.
Council of Science Editors:
Vadas RL. Habitat tools for assessing instream-flow needs for fishes in the upper Roanoke River, Virginia. [Doctoral Dissertation]. Virginia Tech; 1994. Available from: http://hdl.handle.net/10919/28250
12.
White, Allison Lynn.
Spatial and temporal heterogeneity in life history and productivity trends of Atlantic Weakfish (Cynoscion regalis) and implications to fisheries management.
Degree: MS, Fisheries and Wildlife Sciences, 2017, Virginia Tech
URL: http://hdl.handle.net/10919/78707
► The biological characteristics of fisheries stocks that are assessed for management considerations are rarely homogeneous over time or space. However, stock assessment scientists largely ignore…
(more)
▼ The biological characteristics of fisheries stocks that are assessed for management considerations are rarely homogeneous over time or space. However, stock assessment scientists largely ignore this heterogeneity in their models. This thesis addresses the effects of spatial and temporal heterogeneity on stock assessment models using Atlantic Weakfish (Cynoscion regalis) as a case study. First, spatial and temporal variation was incorporated into length-, weight-, and maturity-at-age estimates using mixed-effects models (Chapter Two). The resulting heterogeneous weight and maturity parameters then were applied to per-recruit analyses to examine the sensitivity of biological reference points to spatial and temporal variation in life history attributes (Chapter Three). Mixed-effects life history models incorporating spatial and temporal variation revealed distinct regional and annual trends that were not visible from standard homogeneous models. In several instances, the homogeneous modelling approach produced life history estimates that varied significantly from the spatial and temporal means produced by the heterogeneous models. In some cases, this difference was so great that the homogeneous means were much higher or lower than the heterogeneous means for all regions or years. Minimized AIC statistics revealed that spatially and temporally integrated mixed-effects models were more robust and descriptive of Atlantic Weakfish life history than the standard homogeneous models. Per-recruit and biological reference points derived from these life history estimates in Chapter Three were found to be highly sensitive to spatial and temporal variations in weight parameters. In several cases, reference points used as management targets were so significantly different that ignoring spatial and temporal heterogeneity in Atlantic Weakfish life history would likely cause overfishing and decline of Weakfish in certain regions and years.
Advisors/Committee Members: Jiao, Yan (committeechair), Orth, Donald J. (committee member), Hallerman, Eric M. (committee member).
Subjects/Keywords: Atlantic Weakfish; mixed-effects models; individual variability; spatial heterogeneity; temporal heterogeneity; fish growth; maturity; Yield per-recruit; spawning stock biomass per-recruit; sensitivity analysis
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APA (6th Edition):
White, A. L. (2017). Spatial and temporal heterogeneity in life history and productivity trends of Atlantic Weakfish (Cynoscion regalis) and implications to fisheries management. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/78707
Chicago Manual of Style (16th Edition):
White, Allison Lynn. “Spatial and temporal heterogeneity in life history and productivity trends of Atlantic Weakfish (Cynoscion regalis) and implications to fisheries management.” 2017. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/78707.
MLA Handbook (7th Edition):
White, Allison Lynn. “Spatial and temporal heterogeneity in life history and productivity trends of Atlantic Weakfish (Cynoscion regalis) and implications to fisheries management.” 2017. Web. 17 Jan 2021.
Vancouver:
White AL. Spatial and temporal heterogeneity in life history and productivity trends of Atlantic Weakfish (Cynoscion regalis) and implications to fisheries management. [Internet] [Masters thesis]. Virginia Tech; 2017. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/78707.
Council of Science Editors:
White AL. Spatial and temporal heterogeneity in life history and productivity trends of Atlantic Weakfish (Cynoscion regalis) and implications to fisheries management. [Masters Thesis]. Virginia Tech; 2017. Available from: http://hdl.handle.net/10919/78707
Virginia Tech
13.
Huang, Jian.
Assessing predictive performance and transferability of species distribution models for freshwater fish in the United States.
Degree: PhD, Fisheries and Wildlife Science, 2015, Virginia Tech
URL: http://hdl.handle.net/10919/73477
► Rigorous modeling of the spatial species distributions is critical in biogeography, conservation, resource management, and assessment of climate change. The goal of chapter 2 of…
(more)
▼ Rigorous modeling of the spatial species distributions is critical in biogeography, conservation, resource management, and assessment of climate change. The goal of chapter 2 of this dissertation was to evaluate the potential of using historical samples to develop high-resolution species distribution models (SDMs) of stream fishes of the United States. I explored the spatial transferability and temporal transferability of stream–fish distribution models in chapter 3 and chapter 4 respectively. Chapter 2 showed that the discrimination power of SDMs for 76 non-game fish species depended on data quality, species' rarity, statistical modeling technique, and incorporation of spatial autocorrelation. The area under the Receiver-Operating-Characteristic curve (AUC) in the cross validation tended to be higher in the logistic regression and boosted regression trees (BRT) than the presence-only MaxEnt models. AUC in the cross validation was also higher for species with large geographic ranges and small local populations. Species prevalence affected discrimination power in the model training but not in the validation. In chapter 3, spatial transferability of SDMs was low for over 70% of the 21 species examined. Only 24% of logistic regression, 12% of BRT, and 16% of MaxEnt had AUC > 0.6 in the spatial transfers. Friedman's rank sum test showed that there was no significant difference in the performance of the three modeling techniques. Spatial transferability could be improved by using spatial logistic regression under Lasso regularization in the training of SDMs and by matching the range and location of predictor variables between training and transfer regions. In chapter 4, testing of temporal SDM transfer on independent samples resulted in discrimination power of the moderate to good range, with AUC > 0.6 for 80% of species in all three types of models. Most cool water species had good temporal transferability. However, biases and misspecified spread occurred frequently in the temporal model transfers. To reduce under- or over-estimation bias, I suggest rescaling the predicted probability of species presence to ordinal ranks. To mitigate inappropriate spread of predictions in the climate change scenarios, I recommended to use large training datasets with good coverage of environmental gradients, and fine-tune predictor variables with regularization and cross validation.
Advisors/Committee Members: Frimpong, Emmanuel A. (committeechair), Orth, Donald J. (committee member), Li, Jie (committee member), Jiao, Yan (committee member).
Subjects/Keywords: Species distribution models; discrimination power; calibration; transferability; climate change; machine learning; New River; stream fish
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APA (6th Edition):
Huang, J. (2015). Assessing predictive performance and transferability of species distribution models for freshwater fish in the United States. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/73477
Chicago Manual of Style (16th Edition):
Huang, Jian. “Assessing predictive performance and transferability of species distribution models for freshwater fish in the United States.” 2015. Doctoral Dissertation, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/73477.
MLA Handbook (7th Edition):
Huang, Jian. “Assessing predictive performance and transferability of species distribution models for freshwater fish in the United States.” 2015. Web. 17 Jan 2021.
Vancouver:
Huang J. Assessing predictive performance and transferability of species distribution models for freshwater fish in the United States. [Internet] [Doctoral dissertation]. Virginia Tech; 2015. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/73477.
Council of Science Editors:
Huang J. Assessing predictive performance and transferability of species distribution models for freshwater fish in the United States. [Doctoral Dissertation]. Virginia Tech; 2015. Available from: http://hdl.handle.net/10919/73477
Virginia Tech
14.
Rios, Adyan Beatriz.
Do hurricanes and other severe weather events affect catch per unit effort of reef-fish in the Florida Keys?.
Degree: MS, Fisheries and Wildlife Sciences, 2012, Virginia Tech
URL: http://hdl.handle.net/10919/32885
► Severe weather events frequently affect important marine fish stocks and fisheries along the United States Atlantic and Gulf of Mexico coasts. However, the effects of…
(more)
▼ Severe weather events frequently affect important marine fish stocks and fisheries along the United States Atlantic and Gulf of Mexico coasts. However, the effects of these events on fish and fisheries are not well understood. The availability of self-reported data from two fisheries in a region frequently affected by tropical cyclones provided a unique opportunity to investigate short-term responses to past events. This study involved selecting severe weather events, calculating changes in effort and catch-per-unit- effort (CPUE), and analyzing those changes across various temporal, spatial, and species-specific scenarios. Responses in each variable were analyzed within and across scenario factors and explored for correlations and linear multivariate relationships with hypothesized explanatory variables. A negative overall directional change was identified for logbook fishing effort. Based on both correlations and linear models, changes in logbook fishing effort were inversely related to changes in average maximum wind speed. Severe weather events are more likely to affect fishing effort than catch rates of reef-fish species. However, lack of responses in CPUE may also relate to the ability of this study to detect changes. The temporal and spatial scales analyzed in this study may not have been adequate for identifying changes in effort for the headboat fishery, or in CPUE for either fishery. Although there was no region-wide response in CPUE associated with severe weather events, further research on this topic is necessary to determine if storm-induced changes in fishery data are likely strong, long-lasting, or widespread enough to influence the outcome of stock-wide assessments.
Advisors/Committee Members: Berkson, James M. (committeechair), Porch, Clay (committee member), Orth, Donald J. (committee member), Kelly, Marcella J. (committee member).
Subjects/Keywords: reef-fish; severe weather; tropical cyclone; stock assessment; Florida Keys
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APA (6th Edition):
Rios, A. B. (2012). Do hurricanes and other severe weather events affect catch per unit effort of reef-fish in the Florida Keys?. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/32885
Chicago Manual of Style (16th Edition):
Rios, Adyan Beatriz. “Do hurricanes and other severe weather events affect catch per unit effort of reef-fish in the Florida Keys?.” 2012. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/32885.
MLA Handbook (7th Edition):
Rios, Adyan Beatriz. “Do hurricanes and other severe weather events affect catch per unit effort of reef-fish in the Florida Keys?.” 2012. Web. 17 Jan 2021.
Vancouver:
Rios AB. Do hurricanes and other severe weather events affect catch per unit effort of reef-fish in the Florida Keys?. [Internet] [Masters thesis]. Virginia Tech; 2012. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/32885.
Council of Science Editors:
Rios AB. Do hurricanes and other severe weather events affect catch per unit effort of reef-fish in the Florida Keys?. [Masters Thesis]. Virginia Tech; 2012. Available from: http://hdl.handle.net/10919/32885
Virginia Tech
15.
Kozarek, Jessica Lindberg.
Channel Morphology and Riparian Vegetation Influences on Fluvial Aquatic Habitat.
Degree: PhD, Biological Systems Engineering, 2011, Virginia Tech
URL: http://hdl.handle.net/10919/77172
► As public awareness of river degradation has grown in recent years, the number of stream restoration activities has increased dramatically. Anthropogenic influences at a range…
(more)
▼ As public awareness of river degradation has grown in recent years, the number of stream restoration activities has increased dramatically. Anthropogenic influences at a range of spatial scales from watershed landuse to riparian vegetation management to local channel morphology can have hierarchical relationships to local (meso- and macro-) in-stream habitat characteristics. This research examined these influences first by examining the influence of complex channel morphology on meso-scale brook trout (Salvelinus fontinalis) habitat in Shenandoah National Park, VA, and then by examining the combined influence of watershed urbanization and riparian vegetation (100-200 m reaches) on stream temperature.
Moving beyond one-dimensional (1D) averaged representations of fish habitat, this research explored the distribution of two-dimensional (2D) flow complexity metrics at the meso-habitat scale as explanatory variables for brook trout habitat preferences and as potential metrics to evaluate habitat restoration design. Spatial hydraulic complexity metrics, including area-weighted circulation and kinetic energy gradients, were calculated based on 2D depth averaged modeled velocity distributions in two 100-m reaches on the Staunton River. While there were no statistically significant correlations between kinetic energy gradients or area-weighted circulation and fish density, fish density was positively correlated to the percent of the channel dominated by protruding boulders. The structural complexity of areas with protruding boulders create complex flow patterns suggesting that flow complexity plays an important role in available brook trout habitat preferences at the local scale, although the 2D depth averaged model may not have adequately represented this complexity. The 2D distribution of flow characteristics was then investigated further to quantify areas of flow refugia (low velocity shelters) and the relationship between these areas, traditional measures of habitat quality, and fish biomass. Flow complexity in the vicinity of flow obstructions (in this case, boulders) was investigated further using patch classification and landscape ecology metrics.
The relative influence of riparian vegetation on stream temperature (another important habitat characteristic) in urban and nonurban watersheds was investigated in 27 paired forested and nonforested reaches in PA, MD, and DE. Riparian vegetation and watershed-scale urbanization both influence stream temperature, which can have profound impacts on in-stream ecosystems. Generally, increased urbanization and removal of riparian forest influenced maximum stream temperatures resulting in higher maximum summer stream temperatures (up to 1.8°C); however, the influence of riparian forests (at at 100-200 m reach scale) decreased with increasing urbanization. Extreme maximum summer temperatures, which are a concern for aquatic biota, increased in both frequency and duration in urban nonforested reaches relative to forested reaches indicating that the addition of a forested 100-200 m…
Advisors/Committee Members: Hession, William Cully (committeechair), Wynn, Theresa M. (committee member), Orth, Donald J. (committee member), Dolloff, C. Andrew (committee member), Diplas, Panayiotis (committee member).
Subjects/Keywords: aquatic habitat; boulders; mountain streams; 2D hydraulic models; urbanization; stream temperature; riparian vegetation
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APA (6th Edition):
Kozarek, J. L. (2011). Channel Morphology and Riparian Vegetation Influences on Fluvial Aquatic Habitat. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/77172
Chicago Manual of Style (16th Edition):
Kozarek, Jessica Lindberg. “Channel Morphology and Riparian Vegetation Influences on Fluvial Aquatic Habitat.” 2011. Doctoral Dissertation, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/77172.
MLA Handbook (7th Edition):
Kozarek, Jessica Lindberg. “Channel Morphology and Riparian Vegetation Influences on Fluvial Aquatic Habitat.” 2011. Web. 17 Jan 2021.
Vancouver:
Kozarek JL. Channel Morphology and Riparian Vegetation Influences on Fluvial Aquatic Habitat. [Internet] [Doctoral dissertation]. Virginia Tech; 2011. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/77172.
Council of Science Editors:
Kozarek JL. Channel Morphology and Riparian Vegetation Influences on Fluvial Aquatic Habitat. [Doctoral Dissertation]. Virginia Tech; 2011. Available from: http://hdl.handle.net/10919/77172
Virginia Tech
16.
Shugart-Schmidt, Katelin Leeann Puanani.
Estimating Management Uncertainty for Marine Fisheries in the South Atlantic United States.
Degree: MS, Fisheries and Wildlife Sciences, 2013, Virginia Tech
URL: http://hdl.handle.net/10919/49608
► With the latest reauthorization of the Magnuson-Stevens Fishery Conservation and Management Act (MSA) and the precarious state of many of the nation's fisheries, it has…
(more)
▼ With the latest reauthorization of the Magnuson-Stevens Fishery Conservation and Management Act (MSA) and the precarious state of many of the nation's fisheries, it has become essential to incorporate uncertainty in the process of setting annual catch limits (ACLs) and annual catch targets (ACTs). The accuracy with which we predict landings can be thought of as management uncertainty, and it can be estimated by comparing the predicted landings intended by a regulation to the fisheriesáctual landings estimates. The National Standard 1 Guidelines for the MSA state that management regulations should take into account management uncertainty when establishing ACLs or ACTs, prescribing more precaution when management uncertainty is high. This study compared pre-season landings predictions of managed fish species in the South Atlantic to post-season estimates and investigated the existence of management uncertainty, and evaluated its magnitude and direction. Results indicate that the magnitude of management uncertainty for some stocks in the region may be significant. It appears that recreational fisheries have significantly greater management uncertainty than commercial fisheries, and that commercial fisheries are often producing landings smaller than intended or predicted. No relationship was found between regulatory mechanism or the magnitude of a fishery and management uncertainty. The study also revealed that documentation of the methodology used to determine preseason catch estimates is often not sufficient to repeat estimation procedures. The results of this study will have immediate and direct utility in the setting of future management regulations, ACLs, and ACTs in the South Atlantic region, and perhaps beyond.
Advisors/Committee Members: Berkson, James M. (committeechair), Orth, Donald J. (committee member), McMullin, Steve L. (committee member), McGovern, John Clarke (committee member).
Subjects/Keywords: fisheries; South Atlantic; management uncertainty; implementation error; management error
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APA (6th Edition):
Shugart-Schmidt, K. L. P. (2013). Estimating Management Uncertainty for Marine Fisheries in the South Atlantic United States. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/49608
Chicago Manual of Style (16th Edition):
Shugart-Schmidt, Katelin Leeann Puanani. “Estimating Management Uncertainty for Marine Fisheries in the South Atlantic United States.” 2013. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/49608.
MLA Handbook (7th Edition):
Shugart-Schmidt, Katelin Leeann Puanani. “Estimating Management Uncertainty for Marine Fisheries in the South Atlantic United States.” 2013. Web. 17 Jan 2021.
Vancouver:
Shugart-Schmidt KLP. Estimating Management Uncertainty for Marine Fisheries in the South Atlantic United States. [Internet] [Masters thesis]. Virginia Tech; 2013. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/49608.
Council of Science Editors:
Shugart-Schmidt KLP. Estimating Management Uncertainty for Marine Fisheries in the South Atlantic United States. [Masters Thesis]. Virginia Tech; 2013. Available from: http://hdl.handle.net/10919/49608
Virginia Tech
17.
Peoples, Brandon Kevin.
Applying ecological models to positive interactions among lotic fishes: implications for population and community regulation at multiple spatial scales.
Degree: PhD, Fisheries and Wildlife Science, 2015, Virginia Tech
URL: http://hdl.handle.net/10919/73340
► Positive biotic interactions such as mutualism, commensalism and facilitation are ubiquitous in nature, but historically have received considerably less research attention than negative interactions such…
(more)
▼ Positive biotic interactions such as mutualism, commensalism and facilitation are ubiquitous in nature, but historically have received considerably less research attention than negative interactions such as competition, predation and parasitism. The paucity of research on positive interactions is particularly evident in stream ecosystems and in vertebrate communities. Stream fishes clearly provide an ideal system for advancing research on positive interactions. Many minnows (Cyprinidae) of eastern North America engage in a potentially mutualistic reproductive interaction known as nest association, in which individuals of one species (nest associates) spawn in nests constructed by host species. In nest association, hosts provide unsilted gravel substrate for spawning nest associates, and increased parental care to associate broods. High associate: host egg ratios can create a dilution effect, reducing the probability that host eggs will be preyed upon by egg predators. Nest associative interactions are common, but are relatively understudied compared to other interactions among stream fishes.
The goals of this study were to apply general ecological models to this novel system to (a) gain new insight into the mechanisms structuring nest associative stream fish communities, and (b) to use inference from stream fish communities to potentially expand and improve the general ecological models. These goals required completion of three objectives, including (1) examining the influence of abiotic and biotic contexts on reproductive behavior and fitness outcomes between a cyprinid host and associate, using the biological markets model to generate predictions; (2) examining the utility of the nest web framework (previously only used for cavity nesting vertebrate communities) and the stress gradient hypothesis (previously applied almost exclusively to plant communities) for predicting which associate species spawn on nests built by various nest building species, and the consequences of these choices, respectively; and (3) using two-species occupancy modeling to determine the relative influence of biotic interactions and habitat covariates on the co-occurrence of a host and two nest associates.
To accomplish these goals, I conducted a large-scale experiment to manipulate presence of mutualists (Nocomis leptocephalus, host; Chrosomus oreas, associate), egg predators (biotic context) and habitat quality (abiotic context). I conducted behavioral nest observations and conducted repeated stream fish stream fish community surveys to collect demographic data. I constructed a nest web from observational data, and implemented structural equation modeling through an information-theoretic framework to identify nest web plausibility across a large spatial extent. I tested some predictions of the stress gradient hypothesis by regressing juveniles-per-nest and a metric of cyprinid community structure on a composite measure of physical stress (scaled gradients of catchment-scale agricultural land use and catchment area). I used…
Advisors/Committee Members: Frimpong, Emmanuel A. (committeechair), Orth, Donald J. (committee member), Dolloff, C. Andrew (committee member), Blanc, Lori A. (committee member).
Subjects/Keywords: mutualism; symbiosis; biological markets; experiment; facilitation; stress gradient hypothesis; structural equation modeling; information-theoretic; co-occurrence; occupancy modeling; stream fish; nest association; lotic; habitat; Nocomis
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APA (6th Edition):
Peoples, B. K. (2015). Applying ecological models to positive interactions among lotic fishes: implications for population and community regulation at multiple spatial scales. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/73340
Chicago Manual of Style (16th Edition):
Peoples, Brandon Kevin. “Applying ecological models to positive interactions among lotic fishes: implications for population and community regulation at multiple spatial scales.” 2015. Doctoral Dissertation, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/73340.
MLA Handbook (7th Edition):
Peoples, Brandon Kevin. “Applying ecological models to positive interactions among lotic fishes: implications for population and community regulation at multiple spatial scales.” 2015. Web. 17 Jan 2021.
Vancouver:
Peoples BK. Applying ecological models to positive interactions among lotic fishes: implications for population and community regulation at multiple spatial scales. [Internet] [Doctoral dissertation]. Virginia Tech; 2015. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/73340.
Council of Science Editors:
Peoples BK. Applying ecological models to positive interactions among lotic fishes: implications for population and community regulation at multiple spatial scales. [Doctoral Dissertation]. Virginia Tech; 2015. Available from: http://hdl.handle.net/10919/73340
Virginia Tech
18.
Hua, Dan.
Propagation and monitoring of freshwater mussels released into the Clinch and Powell rivers, Virginia and Tennessee.
Degree: PhD, Fisheries and Wildlife Science, 2015, Virginia Tech
URL: http://hdl.handle.net/10919/51755
► Freshwater mussels (Unionidae) in the United States have experienced dramatic declines, and 25% species are listed as federally endangered. Hence, recovery plans for endangered species…
(more)
▼ Freshwater mussels (Unionidae) in the United States have experienced dramatic declines, and 25% species are listed as federally endangered. Hence, recovery plans for endangered species proposed a strategy of propagation of young mussels for release to natal rivers to augment declining populations. In this study, I conducted laboratory experiments, assessed site suitability for mussel restoration, and evaluated survival and growth rates of released mussels to meet the requirements of recovery plan.
I conducted multiple experiments to develop an improved protocol for juvenile mussel propagation and culture. Significantly greater survival and growth rates were found in newly metamorphosed juveniles of the rainbow mussel (Villosa iris) reared in a substrate of fine sediment and one-month-old juveniles of wavy-rayed lampmussel (Lampsilis fasciola) fed on natural food in pond water. Bio-filter media greatly increased water quality by reducing the concentration of ammonia and nitrite. The negative impacts of flatworm predation and filamentous algae in juvenile culture were controlled, and juvenile escapement was prevented. Juvenile mussels were successfully produced and cultured to stockable size (>15 mm) for release.
I released laboratory-propagated mussels at three historically important sites in Clinch and Powell rivers for the assessment of site suitability. Use of cages was the most effective method to determine site suitability because the free-released mussels (untagged, tagged) had low catchability. Mussels released at Horton Ford, Clinch River, exhibited significantly faster growth. Horton Ford is the most suitable site, while environmental conditions at Fugate Ford, Powell River, are deemed unsuitable for mussel restoration and recovery.
To facilitate the detection of released mussels, I applied Passive Integrated Transponder tags to laboratory-produced juveniles of the endangered Cumberlandian combshell (Epioblasma brevidens) and released them near Brooks Bridge, Powell River. The detection probability increased above 98%. I developed a set of hierarchical Bayesian models incorporating individual variations, seasonal variations, periodic growth stages and growth cessation to estimate survival, detection probability and growth of released mussels in a changing environment. Mussels of E. brevidens exhibited great survival (> 99% per month) and growth, indicating suitable conditions for recovery of this endangered species at this site.
Advisors/Committee Members: Jiao, Yan (committeechair), Neves, Richard J. (committeechair), Orth, Donald J. (committee member), Karpanty, Sarah M. (committee member), Guo, Feng (committee member).
Subjects/Keywords: Freshwater mussel; endangered species; propagation; culture; release; Split-plot design; recirculating system; survival rate; detection probability; growth rate; mark-recapture; PIT tag; hierarchic model; Bayesian
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APA (6th Edition):
Hua, D. (2015). Propagation and monitoring of freshwater mussels released into the Clinch and Powell rivers, Virginia and Tennessee. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/51755
Chicago Manual of Style (16th Edition):
Hua, Dan. “Propagation and monitoring of freshwater mussels released into the Clinch and Powell rivers, Virginia and Tennessee.” 2015. Doctoral Dissertation, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/51755.
MLA Handbook (7th Edition):
Hua, Dan. “Propagation and monitoring of freshwater mussels released into the Clinch and Powell rivers, Virginia and Tennessee.” 2015. Web. 17 Jan 2021.
Vancouver:
Hua D. Propagation and monitoring of freshwater mussels released into the Clinch and Powell rivers, Virginia and Tennessee. [Internet] [Doctoral dissertation]. Virginia Tech; 2015. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/51755.
Council of Science Editors:
Hua D. Propagation and monitoring of freshwater mussels released into the Clinch and Powell rivers, Virginia and Tennessee. [Doctoral Dissertation]. Virginia Tech; 2015. Available from: http://hdl.handle.net/10919/51755
19.
Anane-Taabeah, Gifty.
Characterization of the molecular genetic variation in wild and farmed Nile tilapia Oreochromis niloticus in Ghana for conservation and aquaculture development.
Degree: PhD, Fisheries and Wildlife Science, 2019, Virginia Tech
URL: http://hdl.handle.net/10919/87410
► The Nile tilapia Oreochromis niloticus is an important food source for many people in Africa. However, many wild populations may be at risk of population…
(more)
▼ The Nile tilapia Oreochromis niloticus is an important food source for many people in Africa. However, many wild populations may be at risk of population decline and extinction because of increasing human activities such as overfishing and farming of non-native strains. Understanding the genetic differences among wild populations and comparing them with farmed strains can inform protection of wild populations and also help develop aquaculture strains using native populations as genetic resources. I assessed the genetic differences among tilapia populations using fin-clips I collected between December 2014 and July 2017 from 14 farmed sources, mostly originating from cage farms on the Volta Lake, and 13 wild sources from nine river basins in Ghana. I also conducted a laboratory study with two wild populations to test their tolerance to high water temperature. My research showed that pure O. niloticus populations still occur in Ghanaian rivers, but some have reproduced widely with a similar species, O. aureus, which is not known to occur in Ghanaian rivers. I also found that some wild populations may have reduced population sizes because of overfishing or because their environments have been impacted by illegal mining occurring in almost all Ghanaian rivers. My results indicated that at least two farms were growing the genetically improved farmed tilapia (GIFT) and related varieties, some of which have escaped the farms and mixed with wild populations. The results of my laboratory experiment showed that O. niloticus populations occurring in northern Ghana may be adapted to warmer water temperatures and could be selectively bred and used in aquaculture. The information generated from my research should help in making timely conservation decisions, which should help protect the remnant pure O. niloticus populations in the wild and contribute to developing aquaculture responsibly.
Advisors/Committee Members: Frimpong, Emmanuel A. (committeechair), Orth, Donald J. (committee member), Hallerman, Eric M. (committee member), Jones, Jess W. (committee member).
Subjects/Keywords: Oreochromis niloticus; Oreochromis aureus; Oreochromis mossambicus; Phylogenetic analysis; mitochondrial DNA; DNA microsatellites; West Africa; GIFT strain
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APA (6th Edition):
Anane-Taabeah, G. (2019). Characterization of the molecular genetic variation in wild and farmed Nile tilapia Oreochromis niloticus in Ghana for conservation and aquaculture development. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/87410
Chicago Manual of Style (16th Edition):
Anane-Taabeah, Gifty. “Characterization of the molecular genetic variation in wild and farmed Nile tilapia Oreochromis niloticus in Ghana for conservation and aquaculture development.” 2019. Doctoral Dissertation, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/87410.
MLA Handbook (7th Edition):
Anane-Taabeah, Gifty. “Characterization of the molecular genetic variation in wild and farmed Nile tilapia Oreochromis niloticus in Ghana for conservation and aquaculture development.” 2019. Web. 17 Jan 2021.
Vancouver:
Anane-Taabeah G. Characterization of the molecular genetic variation in wild and farmed Nile tilapia Oreochromis niloticus in Ghana for conservation and aquaculture development. [Internet] [Doctoral dissertation]. Virginia Tech; 2019. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/87410.
Council of Science Editors:
Anane-Taabeah G. Characterization of the molecular genetic variation in wild and farmed Nile tilapia Oreochromis niloticus in Ghana for conservation and aquaculture development. [Doctoral Dissertation]. Virginia Tech; 2019. Available from: http://hdl.handle.net/10919/87410
20.
Sweeten, Sara.
The Effects of Microhabitat and Land Use on Stream Salamander Occupancy and Abundance in the Southwest Virginia Coalfields.
Degree: PhD, Fisheries and Wildlife Science, 2015, Virginia Tech
URL: http://hdl.handle.net/10919/51681
► Large-scale land uses such as residential wastewater discharge and coal mining practices, particularly surface coal extraction and associated valley fills, are of particular ecological concern…
(more)
▼ Large-scale land uses such as residential wastewater discharge and coal mining practices, particularly surface coal extraction and associated valley fills, are of particular ecological concern in central Appalachia. Identification and quantification of both large-scale land use and microhabitat alterations to ecosystems are a necessary first-step aid in mitigation of negative consequences to biota. In central Appalachian headwater streams absent of fish, salamanders are the dominant, most abundant vertebrate predator providing a significant intermediate trophic role. Stream salamander species are considered to be sensitive to aquatic stressors and environmental alterations with past research having shown linkages among microhabitat parameters, and large-scale land use such as urbanization and logging to salamander abundances. However, there is little information examining these linkages in the coalfields of central Appalachia. In the summer of 2013, I visited 70 sites (sampled three times each) in the southwest
Virginia coalfields to collect salamanders and quantify stream and riparian microhabitat parameters. In an information-theoretic framework I compared the effects of microhabitat and large-scale land use on salamander occupancy and abundances. My findings indicate that dusky salamander (Desmognathus spp.) occupancy and abundances are more correlated to microhabitat parameters such as canopy cover than to subwatershed land uses. Brook salamander (Eurycea spp.) occupancy show negative associations to large-scale land uses such as percent recent mining and percent forested. Whereas Eurycea spp. abundances are negatively influenced by suspended sediments, stream bank erosion and stream substrate embeddedness. Management implications of these findings include erosion prevention and
control as well as protection and management of riparian habitats. However, quantifying physical environmental quality such as stream and riparian habitat often can be quite difficult, particularly when there are time or fiscal limitations. In order to accurately assess stream and riparian habitat in a time- and cost- effective manner, the U.S. Army Corps of Engineers (USACE) developed a functional condition index (FCI) assessment for streams that measures 11 stream and riparian parameters along with watershed land use to calculate three different scores: a hydrology score, biogeochemical score, and habitat score (Noble et al 2010). Using the salamander data from 2013, I then analyzed the FCI scores using collected occupancy and abundance analyses. Both analyses supported the Habitat FCI score as it had strong correlations with both occupancy and abundance of three Desmognathus spp., and support the use of the USACE protocol for stream and riparian habitat assessment.
Advisors/Committee Members: Ford, William Mark (committeechair), Schoenholtz, Stephen H. (committee member), Orth, Donald J. (committee member), Craynon, John Raymond (committee member).
Subjects/Keywords: Central Appalachia; coal mining; Desmognathus; Eurycea; headwater streams; habitat assessment; riparian habitat; stream salamanders
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APA (6th Edition):
Sweeten, S. (2015). The Effects of Microhabitat and Land Use on Stream Salamander Occupancy and Abundance in the Southwest Virginia Coalfields. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/51681
Chicago Manual of Style (16th Edition):
Sweeten, Sara. “The Effects of Microhabitat and Land Use on Stream Salamander Occupancy and Abundance in the Southwest Virginia Coalfields.” 2015. Doctoral Dissertation, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/51681.
MLA Handbook (7th Edition):
Sweeten, Sara. “The Effects of Microhabitat and Land Use on Stream Salamander Occupancy and Abundance in the Southwest Virginia Coalfields.” 2015. Web. 17 Jan 2021.
Vancouver:
Sweeten S. The Effects of Microhabitat and Land Use on Stream Salamander Occupancy and Abundance in the Southwest Virginia Coalfields. [Internet] [Doctoral dissertation]. Virginia Tech; 2015. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/51681.
Council of Science Editors:
Sweeten S. The Effects of Microhabitat and Land Use on Stream Salamander Occupancy and Abundance in the Southwest Virginia Coalfields. [Doctoral Dissertation]. Virginia Tech; 2015. Available from: http://hdl.handle.net/10919/51681
21.
Schmitt, Joseph Daniel.
Feeding Ecology of Invasive Catfishes in Chesapeake Bay Subestuaries.
Degree: PhD, Fisheries and Wildlife Science, 2018, Virginia Tech
URL: http://hdl.handle.net/10919/83464
► Blue Catfish Ictalurus furcatus are native to tributaries of the Mississippi River but are now invasive in several Atlantic slope drainages. This includes subestuaries of…
(more)
▼ Blue Catfish Ictalurus furcatus are native to tributaries of the Mississippi River but are now invasive in several Atlantic slope drainages. This includes subestuaries of the Chesapeake Bay, where their feeding ecology and potential impact on native species was largely unknown. We collected stomach contents from 16,110 Blue Catfish at 698 sites in three large subestuaries of the Chesapeake Bay (James, York, Rappahannock rivers). Cumulative prey curves revealed that sample size was sufficient for diet description, though 1,000 – 1500 stomachs were needed per river. Blue Catfish are opportunistic generalists that feed on a broad array of plant and animal material. Logistic regression models reveal that Blue Catfish undergo significant ontogenetic diet shifts to piscivory at larger sizes (P<0.01) though the lengths at which these shifts occur varies by river system (500 – 900 mm total length; TL). Over 60% of Blue Catfish stomachs contained other invasive species, primarily Hydrilla verticillata and Asian clams Corbicula fluminea. Canonical Correspondence Analysis (CCA) revealed that salinity and season explained the most variation in Blue Catfish diet, while Generalized Additive Models (GAMs) demonstrated that there is considerable spatiotemporal and length-based variation in predation of species of concern. Species of concern include American Shad, American Eel, and river herring, which are imperiled, and blue crab, which support valuable fisheries in Chesapeake Bay. Predation of American Shad, American Eel, and river herring was rare (max predicted occurrence in Blue Catfish diets = 8%), while blue crab was much more common in the diet (max predicted occurrence =28%). Predation of American Shad and river herring peaks in freshwater areas in April, while predation of blue crab peaks in brackish areas in October. Predation of all species of concern is highest for large catfish (500 – 1000 mm TL). Field and laboratory-based estimates of consumption rate revealed that Blue Catfish feed at similar rates as Channel Catfish Ictalurus punctatus, and daily ration is estimated to be 2-5% bodyweight per day during warm temperatures, while peak feeding (maximum daily ration) can approach 10% bodyweight per day. While consumption of imperiled species is rare, Blue Catfish could still have negative impacts on these species due to dense catfish populations.
Advisors/Committee Members: Orth, Donald J. (committeechair), Peoples, Brandon Kevin (committee member), Jiao, Yan (committee member), Castello, Leandro (committee member).
Subjects/Keywords: invasion ecology; food habits; diet; blue catfish; flathead catfish; consumption rates; daily ration; prey selectivity; diet breadth; trophic position; omnivory index
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APA (6th Edition):
Schmitt, J. D. (2018). Feeding Ecology of Invasive Catfishes in Chesapeake Bay Subestuaries. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/83464
Chicago Manual of Style (16th Edition):
Schmitt, Joseph Daniel. “Feeding Ecology of Invasive Catfishes in Chesapeake Bay Subestuaries.” 2018. Doctoral Dissertation, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/83464.
MLA Handbook (7th Edition):
Schmitt, Joseph Daniel. “Feeding Ecology of Invasive Catfishes in Chesapeake Bay Subestuaries.” 2018. Web. 17 Jan 2021.
Vancouver:
Schmitt JD. Feeding Ecology of Invasive Catfishes in Chesapeake Bay Subestuaries. [Internet] [Doctoral dissertation]. Virginia Tech; 2018. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/83464.
Council of Science Editors:
Schmitt JD. Feeding Ecology of Invasive Catfishes in Chesapeake Bay Subestuaries. [Doctoral Dissertation]. Virginia Tech; 2018. Available from: http://hdl.handle.net/10919/83464
Virginia Tech
22.
Hoffman, Kinsey H.
Ecohydrologic Indicators of Low-flow Habitat Availability in Eleven Virginia Rivers.
Degree: MS, Biological Systems Engineering, 2015, Virginia Tech
URL: http://hdl.handle.net/10919/56978
► Increasing demand and competition for freshwater is threatening instream uses including ecosystem services and aquatic habitat. A standard method of evaluating impacts of alternative water…
(more)
▼ Increasing demand and competition for freshwater is threatening instream uses including ecosystem services and aquatic habitat. A standard method of evaluating impacts of alternative water management scenarios on instream habitat is Instream Flow Incremental Methodology (IFIM). The primary outputs of IFIM studies are: 1) habitat rating curves that relate habitat availability to streamflow for every species, lifestage, or recreational use modelled; and 2) habitat time series under alternative water management scenarios. We compiled 428 habitat rating curves from previous IFIM studies across 11 rivers in
Virginia and tested the ability to reduce this number based on similarities in flow preferences and responses to flow alteration. Individual site-species combinations were reduced from 428 objects to four groups with similar seasonal habitat availability patterns using a hierarchical, agglomerative cluster analysis. A seasonal habitat availability (SHA) ratio was proposed as a future indicator of seasonal flow preferences. Four parameters calculated from the magnitude and shape of habitat rating curves were proposed as response metrics that indicate how a lifestage responds to flow alteration. Univariate and multivariate analyses of variance and post-hoc tests identified significantly different means for the SHA ratio, QP (F=63.2, p<2e-16) and SK (F=65.6, p<2e-16). A reduced number of instream flow users can simplify the incorporation of aquatic habitat assessment in statewide water resources management.
Advisors/Committee Members: Hession, William Cully (committeechair), Burgholzer, Robert William (committee member), Orth, Donald J. (committee member), Scott, Durelle T. (committee member).
Subjects/Keywords: environmental flows; water resources management; aquatic habitat availability; Instream Flow Incremental Methodology
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APA (6th Edition):
Hoffman, K. H. (2015). Ecohydrologic Indicators of Low-flow Habitat Availability in Eleven Virginia Rivers. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/56978
Chicago Manual of Style (16th Edition):
Hoffman, Kinsey H. “Ecohydrologic Indicators of Low-flow Habitat Availability in Eleven Virginia Rivers.” 2015. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/56978.
MLA Handbook (7th Edition):
Hoffman, Kinsey H. “Ecohydrologic Indicators of Low-flow Habitat Availability in Eleven Virginia Rivers.” 2015. Web. 17 Jan 2021.
Vancouver:
Hoffman KH. Ecohydrologic Indicators of Low-flow Habitat Availability in Eleven Virginia Rivers. [Internet] [Masters thesis]. Virginia Tech; 2015. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/56978.
Council of Science Editors:
Hoffman KH. Ecohydrologic Indicators of Low-flow Habitat Availability in Eleven Virginia Rivers. [Masters Thesis]. Virginia Tech; 2015. Available from: http://hdl.handle.net/10919/56978
Virginia Tech
23.
Susko, Emily Clare.
The effects of life history strategy and uncertainty on a probability-based approach to managing the risk of overfishing.
Degree: MS, Fisheries and Wildlife Sciences, 2012, Virginia Tech
URL: http://hdl.handle.net/10919/76939
► Recent U.S. legislation applies a precautionary approach to setting catch regulations in federal fisheries management. A transparent approach to complying with federal guidelines involves calculating…
(more)
▼ Recent U.S. legislation applies a precautionary approach to setting catch regulations in federal fisheries management. A transparent approach to complying with federal guidelines involves calculating the catch recommendation that corresponds to a specified probability, P*, of exceeding the "true" overfishing limit (OFL) located within an estimated distribution.
The P* methodology aims to manage the risk of overfishing explicitly, but choice of P* alone does not provide sufficient information on all of the risks associated with a control rule—both the probability of overfishing and the severity of overfishing. Rather, the ramifications of P* choices depend on the amount of uncertainty in the stock assessment and on the life history of the species in question. To evaluate these effects on the risks associated with P* rules, my study simulated fishing three example species under three levels of uncertainty.
Trends identified among example species were consistent with predictions from life history. Periodic strategists, which have highly variable recruitment, experienced probabilities of overfishing which exceeded P* and which increased in time. Equilibrium strategists showed more predictable risks of overfishing but may have less capacity to recover from depleted biomass levels. Differences in the size of the OFL distribution—representing differences in levels of uncertainty—led to mixed results depending on whether the distribution was biased or whether uncertainty was fully characterized. Lastly, because OFL distributions are themselves estimates and subject to uncertainty in their shape and size, lower P* values closer to the tails of the estimated distribution produced more variable resulting risks.
Advisors/Committee Members: Berkson, James M. (committeechair), Jiao, Yan (committee member), Conn, Paul (committee member), Orth, Donald J. (committee member).
Subjects/Keywords: gulf menhaden; simulation model; life history; sandbar shark; uncertainty; risk; fisheries management; vermilion snapper; stock assessment
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APA (6th Edition):
Susko, E. C. (2012). The effects of life history strategy and uncertainty on a probability-based approach to managing the risk of overfishing. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/76939
Chicago Manual of Style (16th Edition):
Susko, Emily Clare. “The effects of life history strategy and uncertainty on a probability-based approach to managing the risk of overfishing.” 2012. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/76939.
MLA Handbook (7th Edition):
Susko, Emily Clare. “The effects of life history strategy and uncertainty on a probability-based approach to managing the risk of overfishing.” 2012. Web. 17 Jan 2021.
Vancouver:
Susko EC. The effects of life history strategy and uncertainty on a probability-based approach to managing the risk of overfishing. [Internet] [Masters thesis]. Virginia Tech; 2012. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/76939.
Council of Science Editors:
Susko EC. The effects of life history strategy and uncertainty on a probability-based approach to managing the risk of overfishing. [Masters Thesis]. Virginia Tech; 2012. Available from: http://hdl.handle.net/10919/76939
Virginia Tech
24.
Dickinson, Benjamin David.
Characterizing a Hidden Fishery: Setline Fishing in the New River, Virginia.
Degree: MS, Fisheries and Wildlife Sciences, 2013, Virginia Tech
URL: http://hdl.handle.net/10919/24765
► Catfishes Ictaluridae are important food fish that are harvested from the New River, Virginia by multiple methods, yet standard creel survey approaches do not accurately…
(more)
▼ Catfishes Ictaluridae are important food fish that are harvested from the New River,
Virginia by multiple methods, yet standard creel survey approaches do not accurately sample setline effort, a popular fishing gear for catfish. I characterized the New River setline fishery by estimating setline effort and catch rates of catfish and by-catch in 2011, and by investigating the attitudes and opinions of setline users during 2012. Setline effort was highest during June-August, and declined significantly by mid-September. Several dedicated setline users accounted for a significant portion of total setline effort. Experimental setlines baited with live minnows Cyprinidae proved to be an effective method for catching catfish but caught few walleye Sander vitreus, smallmouth bass Micropterus dolomieu, and muskellunge Esox masquinongy. Estimated by-catch of these species by setline fishers is small compared to catch by hook-and-line anglers, though walleye experienced high setline hooking mortality, and catch rates increased in autumn months. Setlines appear to be part of a larger "way of life" for some rural individuals, who may also hunt, trap, and garden as part of activities to supplement their diet or income. New River setline fishers strongly believe that setline fishing has declined significantly in the New River Valley due to improving socioeconomic status of the region, changing recreational values (such as focus on catch-and-release fishing and paddle sports), increasing recreational traffic and law enforcement presence, and decreasing participation in setline fishing by younger generation.
Advisors/Committee Members: Orth, Donald J. (committeechair), McMullin, Steve L. (committeechair), Copeland, John Rogers (committee member), Murphy, Brian R. (committee member).
Subjects/Keywords: catfish; setline; trotline; human dimensions; by-catch
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APA (6th Edition):
Dickinson, B. D. (2013). Characterizing a Hidden Fishery: Setline Fishing in the New River, Virginia. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/24765
Chicago Manual of Style (16th Edition):
Dickinson, Benjamin David. “Characterizing a Hidden Fishery: Setline Fishing in the New River, Virginia.” 2013. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/24765.
MLA Handbook (7th Edition):
Dickinson, Benjamin David. “Characterizing a Hidden Fishery: Setline Fishing in the New River, Virginia.” 2013. Web. 17 Jan 2021.
Vancouver:
Dickinson BD. Characterizing a Hidden Fishery: Setline Fishing in the New River, Virginia. [Internet] [Masters thesis]. Virginia Tech; 2013. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/24765.
Council of Science Editors:
Dickinson BD. Characterizing a Hidden Fishery: Setline Fishing in the New River, Virginia. [Masters Thesis]. Virginia Tech; 2013. Available from: http://hdl.handle.net/10919/24765
25.
Hatch, Joshua M.
The Effects of Ageing Error on Stock Assessment for Weakfish Cynoscion regalis.
Degree: MS, Fisheries and Wildlife Sciences, 2013, Virginia Tech
URL: http://hdl.handle.net/10919/50988
► Inherent uncertainties in the stock assessment for weakfish have precluded accurate and consistent advice concerning the management of commercial and recreational fisheries. Error within ageing…
(more)
▼ Inherent uncertainties in the stock assessment for weakfish have precluded accurate and consistent advice concerning the management of commercial and recreational fisheries. Error within ageing techniques, used to assess relative age frequencies within commercial and recreational harvest, has been cited as a potential source for uncertainty during assessments of the weakfish fishery. The implications for age-reading error on weakfish stock assessment were explored using measurement-error growth models (i.e. Chapter 1), ageing error matrices within a statistical catch-at-age framework (i.e. Chapter 2), and Monte Carlo simulations to gauge robustness of ignoring this type of uncertainty during fisheries stock assessment (i.e. Chapter 3). Measurement-error growth models typically resulted in weakfish that grew to reach larger sizes, but at slower rates, with median length-at-age being overestimated by traditional von Bertalanffy growth curves, at least for the observed age range. Measurement-error growth models allow for incorporation of ageing uncertainty during nonlinear growth curve estimation, as well as the ability to estimate the ageing error variance. Age-reading error was further considered during statistical catch-at-age analysis of the weakfish fishery, mainly through permutations of true catch-at-age via ageing error matrices constructed from estimates of the ageing error variance, thus reflecting changes in relative age compositions as a consequence of ageing uncertainty. As a result, absolute levels of key population parameters were influenced, but general trends in those parameters tended to be similar, with strong congruency across models as to weakfish stock dynamics in most recent years. Finally, Monte Carlo simulations showed that implications for age-reading error on weakfish stock assessment are varied, depending upon the direction and magnitude of the ageing uncertainty. However, relative trends of parameter estimates over time tended to be similar, resulting in proper allocation of weakfish stock status, regardless of the type of ageing error considered. Furthermore, assuming negligible ageing uncertainty within fishery-independent surveys appears reasonable, as simulations incorporating ageing error within indices of relative abundance showed similar patterns to situations that only considered observation noise.
Advisors/Committee Members: Jiao, Yan (committeechair), Orth, Donald J. (committee member), O'Reilly, Robert Laux (committee member), Smith, Eric P. (committee member).
Subjects/Keywords: Ageing error; Weakfish; Bayesian; Statistical catch-at-age; Simulation
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APA (6th Edition):
Hatch, J. M. (2013). The Effects of Ageing Error on Stock Assessment for Weakfish Cynoscion regalis. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/50988
Chicago Manual of Style (16th Edition):
Hatch, Joshua M. “The Effects of Ageing Error on Stock Assessment for Weakfish Cynoscion regalis.” 2013. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/50988.
MLA Handbook (7th Edition):
Hatch, Joshua M. “The Effects of Ageing Error on Stock Assessment for Weakfish Cynoscion regalis.” 2013. Web. 17 Jan 2021.
Vancouver:
Hatch JM. The Effects of Ageing Error on Stock Assessment for Weakfish Cynoscion regalis. [Internet] [Masters thesis]. Virginia Tech; 2013. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/50988.
Council of Science Editors:
Hatch JM. The Effects of Ageing Error on Stock Assessment for Weakfish Cynoscion regalis. [Masters Thesis]. Virginia Tech; 2013. Available from: http://hdl.handle.net/10919/50988
26.
Doss, Sasha Stevely.
Managing Muskellunge in the New River, Virginia: Effective Regulations and Predation on Smallmouth Bass.
Degree: MS, Fisheries and Wildlife Sciences, 2017, Virginia Tech
URL: http://hdl.handle.net/10919/77440
► Potential predation between fishes of recreational interest has incited many bitter conflicts between angler groups. Large predators, such as esocids, are often at the center…
(more)
▼ Potential predation between fishes of recreational interest has incited many bitter conflicts between angler groups. Large predators, such as esocids, are often at the center of these conflicts because of their capacity to alter fish populations. Such a conflict certainly exists between the Muskellunge Esox masquinongy and Smallmouth Bass Micropterus dolomieu fisheries of the New River,
Virginia. Following the institution of a 42-in minimum-length limit (MLL) on Muskellunge, bass anglers feared that increased Muskellunge abundance might be negatively affecting Smallmouth Bass via increased predation. In order to ascertain the impacts of the 42-in MLL, I estimated the demographics, abundance, and food habits of Muskellunge combined with bioenergetics modeling to assess changes (i) in the quality of the Muskellunge fishery and (ii) in Muskellunge predation on Smallmouth Bass. Additionally, given the likelihood of future regulations to incite similar concerns from bass anglers, I modeled alternative length-limit regulations (iii) to assess their potential to improve fishery quality, thereby laying the groundwork for managers to address angler concerns before they arise. I found substantial increases in population size structure and in average adult density of Muskellunge since the institution of the 42-in MLL, but bioenergetics modeling did not indicate a notable increase in the consumption of Smallmouth Bass. I also found that high MLLs (e.g., 48-in) were likely to promote the largest increases in trophy production of Muskellunge compared to low MLLs or protected-slot limits (PSLs). This study suggests that the current Muskellunge population likely plays a small role in shaping Smallmouth Bass population dynamics and production in the New River; and lays the groundwork for predicting how the impact of Muskellunge on Smallmouth Bass might change under alternative regulations.
Advisors/Committee Members: Castello, Leandro (committeechair), Murphy, Brian R. (committeechair), Orth, Donald J. (committee member), Copeland, John Rogers (committee member).
Subjects/Keywords: Muskellunge; Smallmouth Bass; diet; predation; fisheries management; minimum-length limit; regulations; protected-slot limit
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APA (6th Edition):
Doss, S. S. (2017). Managing Muskellunge in the New River, Virginia: Effective Regulations and Predation on Smallmouth Bass. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/77440
Chicago Manual of Style (16th Edition):
Doss, Sasha Stevely. “Managing Muskellunge in the New River, Virginia: Effective Regulations and Predation on Smallmouth Bass.” 2017. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/77440.
MLA Handbook (7th Edition):
Doss, Sasha Stevely. “Managing Muskellunge in the New River, Virginia: Effective Regulations and Predation on Smallmouth Bass.” 2017. Web. 17 Jan 2021.
Vancouver:
Doss SS. Managing Muskellunge in the New River, Virginia: Effective Regulations and Predation on Smallmouth Bass. [Internet] [Masters thesis]. Virginia Tech; 2017. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/77440.
Council of Science Editors:
Doss SS. Managing Muskellunge in the New River, Virginia: Effective Regulations and Predation on Smallmouth Bass. [Masters Thesis]. Virginia Tech; 2017. Available from: http://hdl.handle.net/10919/77440
Virginia Tech
27.
McManamay, Ryan A.
Providing a Restoration Framework for Regulated Rivers.
Degree: PhD, Fish and Wildlife Conservation, 2011, Virginia Tech
URL: http://hdl.handle.net/10919/77088
► With over 800,000 dams occurring globally and the construction of thousands more being proposed, successful restoration of regulated rivers will depend on the creation of…
(more)
▼ With over 800,000 dams occurring globally and the construction of thousands more being proposed, successful restoration of regulated rivers will depend on the creation of broadly applicable frameworks that provide management solutions by generalizing patterns in habitat and ecology. Based on the prevailing scientific literature, restoring natural stream flows in disturbed rivers is dependent upon developing quantitative, transferable stream flow-ecology relationships. The purpose of my dissertation was to apply a framework to regulated and unregulated streams within an eight-state region of the southeastern US to test its ability to generalize patterns in natural and altered stream flow and develop flow-ecology relationships. I created a simplified, 5-step version of the Ecological Limits of Hydrologic Alteration (ELOHA) framework (Poff et al. 2010). I carried out each of the steps in sequential order for unregulated and dam-regulated streams found in my region. The steps of my restoration framework are as follows:<ol>
Develop a natural flow classification of unregulated streams
Develop a tool that uses landscape characteristics to predict flow class membership
Use the predictive tool or pre-disturbance hydrologic information to classify regulated rivers to natural flow classes
Based on class membership, generalize patterns in hydrologic alteration
Relate ecological patterns to patterns in hydrologic alteration in relation tomorphology, temperature, and landscape disturbance</ol>
Altogether, the results of steps 1-4 suggest that patterns in natural flow dynamics and hydrologic alterations can successfully be placed within a framework and generalized to provide the basis and context for environmental flow management; however, results of step 5 suggest that patterns in flow alteration were poorly related to fish assemblages relative to channel morphology, habitat fragmentation, temperature, and substrate. Thus, the development of patterns in hydrologic alteration using the existing frameworks (including mine) may not be ecologically-relevant. My results suggest that current regulated river restoration should not be dependent upon the development of flow-ecology relationships alone, but the interaction between flow, morphology, and temperature within a landscape disturbance context. These relationships should be incorporated within a hierarchical framework to guide restoration efforts in regulated rivers in the future.
Advisors/Committee Members: Orth, Donald J. (committeechair), Angermeier, Paul L. (committee member), Cantrell, Mark A. (committee member), Wynn, Theresa M. (committee member), Frimpong, Emmanuel A. (committee member), Dolloff, C. Andrew (committeecochair).
Subjects/Keywords: landscape; Hydrologic Landscape Regions; endemic fish; Tennessee River; fragmentation; flow-ecology relationships; dams; hydrology; fluvial geomorphology; environmental flow management
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APA (6th Edition):
McManamay, R. A. (2011). Providing a Restoration Framework for Regulated Rivers. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/77088
Chicago Manual of Style (16th Edition):
McManamay, Ryan A. “Providing a Restoration Framework for Regulated Rivers.” 2011. Doctoral Dissertation, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/77088.
MLA Handbook (7th Edition):
McManamay, Ryan A. “Providing a Restoration Framework for Regulated Rivers.” 2011. Web. 17 Jan 2021.
Vancouver:
McManamay RA. Providing a Restoration Framework for Regulated Rivers. [Internet] [Doctoral dissertation]. Virginia Tech; 2011. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/77088.
Council of Science Editors:
McManamay RA. Providing a Restoration Framework for Regulated Rivers. [Doctoral Dissertation]. Virginia Tech; 2011. Available from: http://hdl.handle.net/10919/77088
Virginia Tech
28.
Odom, Michael Cooper.
Distribution of larval fishes in the Winfield Pool, Kanawha River, and direct impacts of commercial navigation traffic on larval fish survival.
Degree: MS, Fisheries and Wildlife Sciences, 1987, Virginia Tech
URL: http://hdl.handle.net/10919/45899
► Distributions of larval fishes in the Winfield Pool, Kanawha River, West Virginia, were determined by sampling two sites with bongo and push nets. Cyprinids,…
(more)
▼ Distributions of larval fishes in the Winfield Pool, Kanawha River, West
Virginia, were
determined by sampling two sites with bongo and push nets. Cyprinids, clupeids, and
<i>Aplodinotus grunniens</i> dominated collections. Main channel densities were a fraction of the
densities along the shoreline, indicating the importance of the shoreline as a nursery. Diel trends in abundance were evident for several taxa, but were likely caused by diel changes in
gear avoidance and distribution of larvae. Vertical trends in abundance were apparent for
several taxa at the deeper and more lentic sampling site (lower pool). <i>Aplodinotus grunniens</i>
were generally more abundant near the bottom, especially during daylight. Cyprinids were
more abundant near the bottom in mid-June, but displayed no vertical trends on other
sampling dates. Clupeids were more abundant at middepth or surface during daylight, while
equally dispersed or near the bottom at night. Vertical trends were not evident at the
shallower and more lotic site (upper pool) except for <i>Aplodinotus grunniens</i>, which displayed
the same preference for the bottom, as at the lower site.
Advisors/Committee Members: Helfrich, Louis A. (committee member), Orth, Donald J. (committeecochair), Nielsen, Larry A. (committeecochair).
Subjects/Keywords: Fishes; LD5655.V855 1987.O386
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APA (6th Edition):
Odom, M. C. (1987). Distribution of larval fishes in the Winfield Pool, Kanawha River, and direct impacts of commercial navigation traffic on larval fish survival. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/45899
Chicago Manual of Style (16th Edition):
Odom, Michael Cooper. “Distribution of larval fishes in the Winfield Pool, Kanawha River, and direct impacts of commercial navigation traffic on larval fish survival.” 1987. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/45899.
MLA Handbook (7th Edition):
Odom, Michael Cooper. “Distribution of larval fishes in the Winfield Pool, Kanawha River, and direct impacts of commercial navigation traffic on larval fish survival.” 1987. Web. 17 Jan 2021.
Vancouver:
Odom MC. Distribution of larval fishes in the Winfield Pool, Kanawha River, and direct impacts of commercial navigation traffic on larval fish survival. [Internet] [Masters thesis]. Virginia Tech; 1987. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/45899.
Council of Science Editors:
Odom MC. Distribution of larval fishes in the Winfield Pool, Kanawha River, and direct impacts of commercial navigation traffic on larval fish survival. [Masters Thesis]. Virginia Tech; 1987. Available from: http://hdl.handle.net/10919/45899
Virginia Tech
29.
Deweber, Jefferson Tyrell.
The Role of Physiography in the Relationships Between Land Cover and Stream Fish Assemblages.
Degree: MS, Fisheries and Wildlife Sciences, 2010, Virginia Tech
URL: http://hdl.handle.net/10919/32522
► Human alteration of the landscape for agricultural and urban land use has been linked to the degradation of streams and stream biota. Natural physical and…
(more)
▼ Human alteration of the landscape for agricultural and urban land use has been linked to the degradation of streams and stream biota. Natural physical and climatic characteristics, or physiographic template, are important for determining natural land cover and constraining human land use, and are strongly related to stream habitat and stream biotic assemblages. Since the physiographic template differs among watersheds and is an important determinant of the processes being studied, it is important to account for these natural differences among watersheds so that the relationship between land cover and streams can be properly understood. The purpose of this thesis is to develop and assess the utility of a regional framework that classifies watersheds based on physical and climatic predictors of land cover. In Chapter 1, I identified physical and climatic predictors of land cover and classified watersheds into Land cover Distinguished Physiographic Regions (LDPRs) based on these predictors. I was able to identify and create classes based off eight climatic and landform characteristics that determined natural land cover and human land use patterns for both the Eastern and Western U.S. In Chapter 2, I utilized LDPRs to stratify a study region and investigated whether the relationships between land cover and stream fish assemblages varied between these regions. Five commonly used metrics covering trophic, reproductive and taxonomic groupings showed significant variation in their response to agricultural land use across LDPRs. The results suggest that the physiographic differences among LDPRs can result in different pathways by which land cover alterations impact stream fish communities. Unlike other commonly used regional frameworks, the rationale and methods used to develop LDPRs properly accounts for the causal relationship between physiography and land cover. Therefore, I recommend the use of LDPRs as a tool for stratifying watersheds based on physiography in future investigations so that the processes by which human land use results in stream degradation can be understood.
Advisors/Committee Members: Frimpong, Emmanuel A. (committeechair), Orth, Donald J. (committee member), Guo, Feng (committee member).
Subjects/Keywords: stream fish assemblages; physiographic template; land cover; regional framework; watershed classification
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APA (6th Edition):
Deweber, J. T. (2010). The Role of Physiography in the Relationships Between Land Cover and Stream Fish Assemblages. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/32522
Chicago Manual of Style (16th Edition):
Deweber, Jefferson Tyrell. “The Role of Physiography in the Relationships Between Land Cover and Stream Fish Assemblages.” 2010. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/32522.
MLA Handbook (7th Edition):
Deweber, Jefferson Tyrell. “The Role of Physiography in the Relationships Between Land Cover and Stream Fish Assemblages.” 2010. Web. 17 Jan 2021.
Vancouver:
Deweber JT. The Role of Physiography in the Relationships Between Land Cover and Stream Fish Assemblages. [Internet] [Masters thesis]. Virginia Tech; 2010. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/32522.
Council of Science Editors:
Deweber JT. The Role of Physiography in the Relationships Between Land Cover and Stream Fish Assemblages. [Masters Thesis]. Virginia Tech; 2010. Available from: http://hdl.handle.net/10919/32522
Virginia Tech
30.
Brenden, Travis Owen.
Competition Between Age-0 Largemouth Bass And Juvenile Bluegills In A Virginia Pond.
Degree: MS, Fisheries and Wildlife Sciences, 1999, Virginia Tech
URL: http://hdl.handle.net/10919/35705
► I assessed the potential for trophic competition between age-0 largemouth bass and juvenile bluegills by quantifying food resource use similarity in a Virginia recreational…
(more)
▼ I assessed the potential for trophic competition between age-0 largemouth bass and juvenile bluegills by quantifying food resource use similarity in a
Virginia recreational small impoundment and by experimentally stocking the species sympatrically and allopatrically in 1.0 m
3 cages and monitoring mortality, growth, and resource use.
Niche breadth of bluegills in the small impoundment was greater than that of largemouth bass for eight out of nine sampling dates during the summer and fall of 1997. Virtually every type of item consumed by largemouth bass also was consumed by bluegills. In spite of this, diet overlap between the species was low. Largemouth bass fed primarily on Calanoida, Ephemeroptera, and fish, while bluegills consumed Diptera and Cyclopoida. The fishery of the impoundment consisted of relatively high and moderate densities of slow- and average-growing largemouth bass and panfish, respectively. If the fishery was managed to provide a high density of small bluegill, largemouth bass and bluegill might compete considering the number of prey items shared.
Manipulative cage experimentation, which consisted of stocking 5 largemouth bass alone, 10 bluegill alone, 5 largemouth bass and 10 bluegill, 5 largemouth bass and 30 bluegill, and 15 largemouth bass and 10 bluegill in cages, indicated that largemouth bass and bluegills can compete and that there exists a strong asymmetry in their competitive relationship. Bluegills had a much stronger impact on largemouth bass than the reverse. When stocked alone, largemouth bass grew significantly larger than when stocked with either 10 or 30 bluegills. There were no significant differences in bluegill growth rates except between bluegills stocked alone and bluegills stocked with 15 largemouth bass. The analysis of food resource use indicates that Copepoda and Diptera larvae may be the limiting resources catalyzing the competitive interaction.
This research suggests that a competitive juvenile bottleneck could occur, depending largely on whether overwinter survival of largemouth bass is size related. Competition between largemouth bass and bluegills may explain why enhancement stocking of fingerling largemouth bass typically is not successful. Further research is needed on the appropriate timing and length at stocking of introductory largemouth bass stockings. Additionally, I recommend that resource partitioning and competition between largemouth bass and bluegills be explored in connection with studies concerning overwinter survival and angling opportunities in small impoundments. Competition between the species may impose an ecological constraint that restricts achievable options in certain systems.
Advisors/Committee Members: Murphy, Brian R. (committeechair), Orth, Donald J. (committee member), Ney, John J. (committee member).
Subjects/Keywords: stocking; panfish option; diet overlap; competition; small impoundment
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APA (6th Edition):
Brenden, T. O. (1999). Competition Between Age-0 Largemouth Bass And Juvenile Bluegills In A Virginia Pond. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/35705
Chicago Manual of Style (16th Edition):
Brenden, Travis Owen. “Competition Between Age-0 Largemouth Bass And Juvenile Bluegills In A Virginia Pond.” 1999. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/35705.
MLA Handbook (7th Edition):
Brenden, Travis Owen. “Competition Between Age-0 Largemouth Bass And Juvenile Bluegills In A Virginia Pond.” 1999. Web. 17 Jan 2021.
Vancouver:
Brenden TO. Competition Between Age-0 Largemouth Bass And Juvenile Bluegills In A Virginia Pond. [Internet] [Masters thesis]. Virginia Tech; 1999. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/35705.
Council of Science Editors:
Brenden TO. Competition Between Age-0 Largemouth Bass And Juvenile Bluegills In A Virginia Pond. [Masters Thesis]. Virginia Tech; 1999. Available from: http://hdl.handle.net/10919/35705
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Open Access Theses and Dissertations
