Dissertations / Theses on the topic 'Oyster fisheries'
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1
Rubio, Ana M. "Environmental influences on the sustainable production of the Sydney rock oyster Saccostrea glomerata : a study in two Southeastern Australian estuaries /." View thesis entry in Australian Digital Theses Program, 2007. http://thesis.anu.edu.au/public/adt-ANU20080618.091057/index.html.
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Harding, Juliana Maria. "Ecological interactions between benthic oyster reef fishes and oysters." W&M ScholarWorks, 2000. https://scholarworks.wm.edu/etd/1539616684.
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Restoration of oyster reef structures rehabilitates habitats and the multi-level ecological communities built on eastern oysters (Crassostrea virginica), the keystone species. Quantitative descriptions of ecological interactions within a habitat are required to delineate essential fish habitats for management and protection. Parallel development of primary (oysters) and secondary trophic levels (benthic fishes) offer an ecological metric of restoration progress over time. The interaction between larval oysters and larval fishes (e.g., Gobiosoma bosc, Chasmodes bosquianus) is quantitatively examined. Oyster settlement estimates for Palace Bar reef, Piankatank River, Virginia are of the same order of magnitude as field densities of recently settled oysters. Benthic fish settlement estimates are within an order of magnitude of observed adult densities. Zooplankton community composition around the reef is temporally variable and plankton densities range from 10 2--106 animals per m3 across temporal scales. Nocturnal densities of naked goby and striped blenny larvae around Palace Bar reef were 3 to 4 orders of magnitude higher than densities observed during daylight hours. Diurnal changes in larval fish abundance near Palace Bar reef are related to ambient light intensities and diurnal vertical migration by prey species. Naked goby, striped blenny, and feather blenny (Hypsoblennius hentzi) larvae selectively consumed bivalve veligers, in multi-factorial laboratory feeding experiments. Temporal co-occurrence of larval oysters and larval fishes was not observed in 1996 field collections although historic oyster settlement data strongly support the probability of co-occurrence during most years. Two different methods are used to estimate the larval oyster - larval fish interaction in the absence of field data. Given existing oyster and fish demographics on Palace Bar reef, larval fishes have the capacity to drastically reduce, perhaps eliminate, local veliger populations if they co-occur. The strength of this interaction is directly related to oyster demography-fecundity relationships. In the absence of veligers, larval fishes consume other plankton taxa that are abundant around the reef. Naked gobies and striped blennies are generalists. Oyster reefs provide optimal rather than essential habitat. Reef restoration will facilitate development of related ecological communities by providing optimal habitat conditions for these ubiquitous estuarine species.
3
Locke, Diana. "Oyster fisheries management of Maryland's Chesapeake Bay." ScholarWorks, 1998. http://scholarworks.waldenu.edu/dilley/7.
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This study examines the concept of property rights in relation to fisheries resource management in the Maryland oyster fishery. An analysis of the past and present state of this fishery on the Chesapeake Bay focused on the administrative, biological, social, economic, and political influences in fisheries management and their potential consequences. This single fishery once provided a quarter of America's oysters but, if the oyster population decline continues, it may soon become a memory. Though Maryland has a dual property rights structure, private and public, the public fishery predominates. The reasons why privatization has not been a successfully implemented strategy, and whether the Maryland fishery embodies a unique situation better served by other management strategies, were addressed, and community-based alternatives from other types of fisheries were evaluated for their efficacy and applicability to Maryland. Historical and current information on Chesapeake oyster populations, events contributing to population fluctuations, and changes in fisheries management strategies were examined for any causal trends and compared and contrasted with other fisheries. The study found that culture and job satisfaction prevents privatization from becoming an accepted property rights management strategy in Maryland. This study also illustrates how cooperative fisheries management strategies can address nonmonetary benefits, traditional values, and coastal community structures, while achieving a sustainable harvest, preserving a traditional way of life, and restoring habitat and the oyster's role in the Bay's ecology. Any changes in the future will likely be directed toward changing the rules of management and harvest for the public grounds. If oyster production is to be increased in the Chesapeake Bay, the cooperation, consent, and responsibility of the watermen are needed for any policy to be successfully implemented. The future of fisheries management will not and cannot be confined to fisheries biology and population counts. It will need to encompass a broad arena of disciplines working together toward a common goal.
4
Ford, Courtney B. Wallace Richard K. "Improving tolerance to hypoxia in the eastern oyster, Crassostrea virginica." Auburn, Ala., 2005. http://repo.lib.auburn.edu/2005%20Summer/master's/FORD_COURTNEY_4.pdf.
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Bromley, Carolyn Anne. "Science-based management strategies for the commercial and environmental sustainability of the European oyster, Ostrea edulis L." Thesis, Queen's University Belfast, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.695264.
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Congrove, Michael Spohn. "A Bio-Economic Feasibility Model for Remote Setting: Potential for Oyster Aquaculture in Virginia." W&M ScholarWorks, 2008. http://dspace.swem.wm.edu/handle/10288/1120.
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Thunberg, Eric M. "A decision model to evaluate the cost-effectiveness of alternative Virginia oyster grounds management strategies." Thesis, Virginia Tech, 1985. http://hdl.handle.net/10919/43041.
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Public and private concern over the decline of Virginia's
oyster industry prompted the General Assembly (GA) in
1977 and 1983 to commission its Joint Legislative Audit and
Review Commission (JLARC) to examine the State's oyster
grounds management policies. In response to JLARC's findings
the GA directed Virginia Marine Resources Commission
(VMRC) to construct and implement an oyster fisheries management
plan. The GA set as the plan's objective to achieve
the greatest production level possible subject to limits of
physical resource availability and technical feasibility.
That the plan should be attentive to cost-effectiveness was
also expressed by the GA.
In developing its management plan VMRC must consider a
variety of environmental, economic and political factors
affecting the production and harvest of market oysters. A
linear programming model developed for VMRC's use in evaluating alternative oyster grounds management strategies is described. The objective of the programming model is to minimize the public plus private cost of producing a prespecified level of market oyster harvest over a ten year planning horizon. The model includes as its activities the different aquacultural techniques used by private planters and VMRC in its repletion program. The many environmental, economic and political factors are incorporated into the model's constraints and technical coefficients.
Several management alternatives are evaluated with the
model. The results of these analyses indicate that without
a fundamental in the oyster repletion program, even if new
oyster grounds management policies are considered, there
would be little change in public grounds market oyster harvest
over current levels. Under revised repletion program practices, however, marked increases in public grounds harvest could be effected for relatively small increases in repletion program budget allocations over current levels.Master of Science
8
Schulte, David M. "Unprecedented Restoration of a Native Oyster Metapopulation." W&M ScholarWorks, 2012. https://scholarworks.wm.edu/etd/1539617928.
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9
Bienlien, Lydia M. "Influence of Perkinsus Marinus Infection and Oyster Health on Levels of Human-Pathogenic Vibrios in Oysters." W&M ScholarWorks, 2016. https://scholarworks.wm.edu/etd/1477068161.
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The eastern oyster Crassostrea virginica is an ecologically and commercially important species whose natural populations have been devastated by overharvesting, habitat destruction, and disease, but the rapid growth of oyster aquaculture has shown potential to restore the economic significance of this species. A key threat to the growth and sustainability of oyster aquaculture is the association of human-pathogenic Vibrio bacteria with product marketed for raw consumption. Two Vibrio species, Vibrio vulnificus and Vibrio parahaemolyticus, are the causes of the highest rates of seafood consumption-related mortality and gastrointestinal illness, respectively. Identification of the factors influencing V. vulnificus and V. parahaemolyticus prevalence and intensity in oysters is fundamental to better risk management. Within the oyster, these bacterial species interact with the same tissues as the prevalent oyster parasite, Perkinsus marinus, yet little is known about the effect of P. marinus infection on bacterial levels. Answering the fundamental question of whether P. marinus correlates with V. vulnificus and V. parahaemolyticus levels in oysters was the focus of this research. Oysters were deployed in the York River, Gloucester Point, VA, where both Vibrio species and P. marinus are endemic, and were sampled at five time points when levels of both P. marinus and Vibrio spp. were expected to be high in oysters. Abundance of all three organisms and pathogenic strains of V. parahaemolyticus were determined in individual oysters using molecular methods to investigate potential correlations between parasite and bacterial abundance. Additionally, the levels of V. vulnificus and V. parahaemolyticus in relation to histopathology associated with P. marinus infection and other conditions were determined. The following year, manipulation of P. marinus disease progression, which is slowed by lower salinities and favored by higher salinities, was attempted by deploying oysters at two additional sites of different salinities to gain insight into whether the timing of P. marinus infection emergence directly influences Vibrio levels. No correlation was observed between total abundance of P. marinus and either V. vulnificus or V. parahaemolyticus. Manipulation of P. marinus disease progression produced no effect on P. marinus emergence, so this yielded no insight into P. marinus-Vibrio interactions. Histopathological analyses did not reveal any correlations between P. marinus ranking, distribution, or associated tissue damage and Vibrio spp. levels. Though few in number, oysters infected by Haplosporidium nelsoni were characterized by higher levels of V. vulnificus, and oysters of peak gametogenic development had significantly higher levels of pathogenic strains of V. parahaemolyticus. The results with regard to H. nelsoni and gametogenic state warrant further study. The primary conclusion of this study is that oyster health has little influence on levels of human-pathogenic Vibrio species in oysters, inter-host variability in Vibrio levels is likely explained by other factors.
10
Frey, Devin. "A Machine Learning Approach to Determine Oyster Vessel Behavior." ScholarWorks@UNO, 2016. http://scholarworks.uno.edu/td/2253.
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A support vector machine (SVM) classifier was designed to replace a previous classifier which predicted oyster vessel behavior in the public oyster grounds of Louisiana. The SVM classifier predicts vessel behavior (docked, poling, fishing, or traveling) based on each vessel’s speed and either net speed or movement angle. The data from these vessels was recorded by a Vessel Monitoring System (VMS), and stored in a PostgreSQL database. The SVM classifier was written in Python, using the scikit-learn library, and was trained by using predictions from the previous classifier. Several validation and parameter optimization techniques were used to improve the SVM classifier’s accuracy. The previous classifier could classify about 93% of points from July 2013 to August 2014, but the SVM classifier can classify about 99.7% of those points. This new classifier can easily be expanded with additional features to further improve its predictive capabilities.
11
March, Richard Alan. "An analysis of the effects of institutional, biological and economic forces on the Virginia oyster fishery." Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/49834.
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Gallegos, David X. "A GIS-Centric Approach for Modeling Vessel Management Behavior System Data to Determine Oyster Vessel Behavior on Public Oyster Grounds in Louisiana." ScholarWorks@UNO, 2014. http://scholarworks.uno.edu/td/1918.
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The satellite communications system called the Vessel Management System was used to provide geospatial data on oyster fishing over the nearly 1.7 million acres of the public water bottoms in Louisiana. An algorithm to analyze the data was developed in order to model vessel behaviors including docked, gearing, fishing and traveling. Vessel speeds were calculated via the Haversine formula at small and large intervals and compared to derive a measure of linearity. The algorithm was implemented into software using Python and inserted into a PostgreSQL database supporting geospatial information. Queries were developed to obtain reports on vessel activities and daily effort expended per behavior. ArcGIS was used to display and interpret the patterns produced by the vessel activity, yielding information about fishing activity clusters and effort which implied the location and productiveness of oyster reefs.
13
Arfken, Ann. "The Eastern Oyster Microbiome and its Implications in the Marine Nitrogen Cycle." W&M ScholarWorks, 2017. https://scholarworks.wm.edu/etd/1516639592.
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Microbial communities associated with a particular space or habitat, or microbiomes, play significant roles in host health and the regulation of biogeochemical cycles. In oysters these microbiomes may be important contributors in the removal of biologically available nitrogen (N) from the coastal and marine environment through the process of denitrification. Denitrification is the microbially mediated step-wise reduction of nitrate (NO3-) or nitrite (NO2-) to N2 gas. Excess nitrogen in the Chesapeake Bay has been implicated in the increase of eutrophication and other detrimental effects including harmful algal blooms, hypoxia, and loss of benthic communities. Oyster reefs have been shown to enhance the rates of denitrification in nearby sediments, but little is known about the oyster microbiomes or associated microbes responsible for denitrification (denitrifiers). Furthermore, the identification of the oyster core microbiome, or set of resident microbes continually present in the oyster, is relatively unknown. Assessing the stable underlying core is necessary to evaluate and predict the effect of varying environmental conditions on the oyster microbiome and oyster denitrification. A combined 16S targeted metagenomic and metabolic inference approach was used in this study to investigate the gill, gut and shell microbiomes of the eastern oyster (Crassostrea virginica) and their associated denitrifiers in response to spatial and temporal changes. Denitrification activity was linked to community structure using methods such as quantitative PCR of nitrous oxide reductase genes (nosZ) and 15N isotope pairing technique with experimental flow-through design. The oyster gill, gut, and shell microbiomes all showed distinct and unique core microbiomes, suggesting an importance of the core to oyster function or health. Denitrifier abundance and activities were most consistent in the shell microbiomes indicating a stable, pool of potential denitrifiers for oyster denitrification. In comparison, oyster gill and gut denitrifier abundances and activities were highly variable and likely related to transient denitrifiers ingested with food particles. Additionally, denitrifiers demonstrated niche differentiation between the different oyster microbiomes, indicating different groups of denitrifiers are responsible for performing denitrification in the oyster. Assessing the stability and variability of the oyster microbiome and associated denitrifiers provides a greater understanding of the oyster’s role in denitrification and the mitigation of excess N in marine and coastal environments.
14
Shefi, Debra Gayle. "The development of cutters in relation to the South Australian oyster industry : an amalgamation of two parallel developing industries /." Access full text, 2006. http://ehlt.flinders.edu.au/archaeology/department/publications/PDF%20Theses/Deb%20Sheffi%202006.pdf.
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Thesis (M.Mar.Archaeol.) -- Flinders University, Department of Archaeology, 2006."A thesis submitted in partial fulfilment of the requirements for the degree of Master of Maritime Archaeology, Department of Archaeology, Flinders University". "May 2006". Includes bibliographical references (leaves 101-105). System requirements for remote version: Adobe Acrobat Reader to view PDF file.
15
McKelvey, Fionnuala. "Population ecology and fisheries management of the native oyster, Ostrea edulis L. in Lough Foyle." Thesis, University of Ulster, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241729.
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Molesky, Thomas J. "Interactions between oyster reefs and adjacent sandflats : effects on microphytobenthos and sediment characteristics /." Electronic version (Microsoft Word), 2003. http://dl.uncw.edu/etd/2003/moleskyt/tommolesky.doc.
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Burke, Russell Paul. "Alternative substrates as a native oyster (Crassostrea virginica) reef restoration strategy in Chesapeake Bay." W&M ScholarWorks, 2010. https://scholarworks.wm.edu/etd/1539616589.
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Oyster shell for native oyster reef restoration is scarce in Chesapeake Bay and other estuaries (Chapter 1). Consequently, alternative substrates merit consideration in oyster restoration. This dissertation examines the suitability of shell alternatives, including granite, concrete, limestone marl, concrete modules and reefballs with reef surveys and experiments in the Rappahannock and Lynnhaven Rivers of Chesapeake Bay. Oyster recruitment, growth, survival, density, biomass, condition, and disease stress, as well as reef accretion and persistence, were measured. In the Lynnhaven River, intertidal riprap had a mean density of 978 oysters m-2 (165 g AFDM m-2) and peak densities > 2000 oysters m-2 (Chapter 2), which are among the highest abundances on alternative reefs, shell or otherwise. Riprap reefs supported a robust population size structure, signifying consistent annual recruitment and reef sustainability. Riprap age (older > younger) and location influenced reef performance; granite and concrete both supported dense oyster-mussel assemblages. In 2005 and 2007, oyster and mussel population structure, density and biomass were quantified on a novel, subtidal concrete modular reef deployed in 2000 in the Rappahannock River (Chapter 3). The reef was not seeded or harvested. Densities (m-2 river bottom) were very high for oysters (2005: 991 m-2; 2007: 2191 m-2) and mussels (2005: 8433 m-2; 2007: 6984 m-2) and comparable to the highest densities on shell reefs. An adjoining 0.44 ha array of concrete reefs (Steamer Rock) was deployed in 1994 and sampled in 2006. These reefs contained > 4 million oysters and > 30 million mussels. Oysters from both reef systems had low disease prevalence and intensity. In a field experiment (Chapter 4), treatments simulating oyster habitat were placed at three intertidal sites in Long Creek of the Lynnhaven River. Granite had highest oyster recruitment and abundance (density > 1500 m-2 and biomass > 200 g AFDM m-2). Many reefs reached a mature state after two years. By Year 3, some reefs had accreted 15-20 L of shell m-2 river bottom, and contained three year classes; some treatments had > 30 % of live oysters growing on other oysters. Large oysters (> 95 mm shell height) had lower intensities of Dermo infection than smaller (60-90 mm) oysters. These patterns indicate that oyster disease tolerance has developed in these high-salinity waters, and highlight the importance of substrate type and reef location in ecological oyster reef restoration. In summer 2006, nine reefs were constructed at two shoreline sites in the Lynnhaven River (Chapter 5), three each of oyster shell (OS), riprap (RR), and concrete modules (CM). Six reefballs were placed at each site, half pre-seeded with hatchery-reared oysters. Finally, in situ setting of triploid oyster larvae on OS, RR and CM reefs was attempted. After 2.5 yrs, all reefs had high oyster density and biomass (unseeded: 150-1200 m -2, 150-600 g AFDM m-2; seeded: 30-1800 oysters m -2), and sustainable accretion rates (8-15 L m-2 yr -1); diploid and triploid oysters had light Dermo infections. Consequently, alternative substrates can serve as effective oyster reefs under diverse conditions in subtidal and intertidal environments of Chesapeake Bay.
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Chuindja, Ngniah Christian. "Application of Web Mashup Technology to Oyster Information Services." ScholarWorks@UNO, 2012. http://scholarworks.uno.edu/td/1568.
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Web mashup is a lightweight technology used to integrate data from remote sources without direct access to their databases. As a data consumer, a Web mashup application creates new contents by retrieving data through the Web application programming interface (API) provided by the external sources. As a data provider, the service program publishes its Web API and implements the specified functions.
In the project reported by this thesis, we have implemented two Web mashup applications to enhance the Web site oystersentinel.org: the Perkinsus marinus model and the Oil Spill model. Each model overlay geospatial data from a local database on top of a coastal map from Google Maps. In addition, we have designed a Web-based data publishing service. In this experimental system, we illustrated a successful Web mashup interface that allows outside developers to access the data about the local oyster stock assessment.
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McCulloch, Danielle. "PELAGIC FISH DIVERSITY AND DENSITY ON AND OFF RESTORED OYSTER REEF HABITAT." VCU Scholars Compass, 2017. https://scholarscompass.vcu.edu/etd/5180.
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The heterogeneity provided by structured habitats is important in supporting diverse and dense fish communities. The biogenic reefs created by the native Eastern Oyster, Crassostrea virginica, were once the dominant structural habitat in Chesapeake Bay, and have since declined to less than 1% of historic estimates. Conflicting results on the effects of oyster reef restoration on pelagic fish assemblages make further investigation necessary. Incorporating multiple sampling strategies may help elucidate oyster reef habitat influence on fish assemblages. This study used multi-panel gillnets, hydroacoustic technology, and day-night sampling to describe pelagic fish assemblages on and off oyster reef habitat in the lower Piankatank River, VA. Data from oyster reef habitat, adjacent sandy-mud bottom habitat, and unstructured sandy habitat outside of a reef restoration area compared fish diversity, species composition, and density among habitat types. A multivariate analysis using day of the year, day or night, and habitat type as model terms found temporal factors explained variation in fish distribution more than habitat. Fish diversity varied significantly with day or night and habitat type. Diversity and density were significantly higher at night, demonstrating the necessity of nocturnal sampling in fish assemblage research. Results from this study conclude that fish assemblages were not significantly more diverse or denser on reef than non-reef habitat. We suggest that future work should concentrate on studying areas where oyster reef habitat comprises a larger proportion of the study area.
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Karp, Melissa Ann. "Influence of Structural Complexity and Location on The Habitat Value of Restored Oyster Reefs." W&M ScholarWorks, 2016. https://scholarworks.wm.edu/etd/1477068135.
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In the Chesapeake Bay, < 1% of the historic oyster population remains, and efforts have been increasing to restore oysters and the services they provide. Building reefs that successfully provide ecosystem services–especially habitat and foraging grounds–may require different restoration techniques than those previously used, and success may depend on reef morphology (complexity), location, and environmental conditions. Salinity and habitat complexity are two important factors that may interact to effect benthic communities and predator-prey interactions on restored reefs. The goals of this project were: (1) Characterize the benthic communities on restored oyster reefs in lower Chesapeake Bay, and (2) examine the effects of structural complexity and salinity on benthic communities and predator-prey interactions. A two-year field survey of restored reefs was carried out in four rivers in lower Chesapeake Bay to characterize faunal communities on restored reefs and to quantify the effect of reef complexity on faunal communities. A laboratory mesocosm experiment was conducted to examine the effect of reef complexity on predator foraging. In total, 61 macrofaunal species were identified among all samples, and restored reefs supported on average, 6,169 org/m2 and 67.88 g-AFDW/m2. There were significant differences in the community composition and diversity among the rivers, and salinity was the environmental factor that best explained the observed differences in species composition across the rivers. Salinity and rugosity (i.e., structural complexity) both positively affected diversity, while salinity negatively affected macrofaunal abundance and biomass. Oyster density and rugosity positively affected macrofaunal biomass, and oyster density positively affected mud crab, polychaete, and mussel densities. In the mesocosm experiment, predator foraging, measured by proportion and number of prey consumed, was significantly reduced in the presence of oyster shell structure. However, predators were able to consume more prey when prey density was increased, even in the presence of oyster shell structure. These results combine to enhance our understanding of the benefits of increased habitat complexity for both prey and predators on restored oyster reefs. Increasing complexity worked to increase the abundance, biomass, and diversity of organisms inhabiting restored reefs, and even though predator consumption was reduced in the presence of structure compared to non-structured habitat, predators were able to consume more prey individuals when prey density was increased. Therefore, increasing the structure of oyster reef habitat may benefit prey species by providing refuge habitat, and benefit predators by providing an increased abundance of available prey items.
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Knight, Peter David, and n/a. "Where did we go wrong? : a critical assessment of management in the Bluff Oyster Fishery." University of Otago. School of Surveying, 2008. http://adt.otago.ac.nz./public/adt-NZDU20081218.160813.
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More than a century of dredging for oysters in the Foveaux Strait has resulted in a decimated fishery. In 1999 the Parliamentary Commissioner for the Environment asked the question: Where did we go wrong? This thesis provides answers to this question by presenting information provided by the Bluff oyster fishermen. In order to gain as much exposure to the community of fishermen as possible, a cumulative period of approximately six months was spent living in the town of Bluff between 2002 and 2007. During this time relationships were built with key informants, and a total of more than 50 community members were interviewed. The thesis describes the practical knowledge of the oyster fishermen, and places it in the context of more that 40 years of modem scientific studies concerned with the fishery. The finding are that since 1996 when the Quota Management System was introduced in the fishery, the most knowledgeable and responsible people in the fishery have been systematically excluded from roles in management. The practical knowledge of fishermen has been discounted in an industry and government led management system, which is an elaborate justification for continued maximum exploitation of the fishery. The theoretical contribution of the thesis lies in its description of belonging as a factor as important as that of property-rights in a sustainable resource system. The practical knowledge and conservation-mindedness of the fishery elders are characteristics of belonging, but not necessarily of ownership. Fishery management should recognize belonging as cultural capital, and make use of it under the present system (i.e. the Quota Management System) by according fishermen rights of management and access to the oyster fishery.
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Bove, Andrew P. ""It Could Be a Big Industry"| Regimes of Value and the Production of Locality Among Oyster Farmers in Southern Maryland." Thesis, The George Washington University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1556620.
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People engaged in small-scale and commercial oyster aquaculture in Southern Maryland negotiate bundled regimes of value in creating a sense of locality through their interactions with oysters. These regimes of value are oysters as food, oysters as agents of ecological restoration, and oysters as a signifier of cultural heritage. The degree to which each regime is valued in relation to the others is highly variable between individuals and contexts. The sense of locality that they produce is constructed against the backdrop of perceived failures of government to adequately protect the resources of the Chesapeake Bay and the livelihoods that depend upon it. Oyster aquaculture has become seen as a way to sustainably revitalize Maryland's oyster industry while directly contributing to the restoration of the Chesapeake Bay's ecosystems.
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Pfirrmann, Bruce William. "Ecosystem Services of Restored Oyster Reefs in a Chesapeake Bay Tributary: Abundance and Foraging of Estuarine Fishes." W&M ScholarWorks, 2017. https://scholarworks.wm.edu/etd/1516639466.
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Oyster reef restoration may enhance the production of ecologically or economically important fish species, an ecosystem service, by providing refuge and foraging habitat. Predicting the effects of oyster habitat restoration on fisheries production in Chesapeake Bay requires a better understanding of fish habitat use, trophic dynamics, and the processes leading to production on a habitat-scale. The objective of this thesis was to evaluate the influence of restored subtidal oyster reefs on the abundance and foraging patterns of mobile estuarine fishes. Specifically, I compared the 1) abundance, 2) stomach fullness, 3) diet composition, and 4) daily consumption rate of fishes collected from restored oyster reef habitat and from unstructured (control) habitat in the Lynnhaven River System (LRS), Virginia, a tributary of Chesapeake Bay. I sampled fishes from April – October 2016 to assess seasonal abundance and diet trends using multi-panel gill nets, and conducted 24-hour sampling events in July and September 2016 to assess daily foraging patterns and estimate habitat-specific consumption rates. The most abundant non-filter feeding fishes collected all came from the Sciaenid (drum) family: spot (Leiostomus xanthurus), silver perch (Bairdiella chrysoura), and Atlantic croaker (Micropogonias undulatus). Overall catch in oyster reef habitat was reduced relative to unstructured bottom, but species-level responses to habitat type varied. Stomach fullness trends varied by species but were associated with habitat type. Benthic prey dominated the diet of all three species, and evidence of habitat-related shifts in diet composition were apparent. Reef-affiliated prey contributed most prominently to silver perch, comprising nearly 30 – 50 % by weight. The daily consumption rate and total daily caloric intake of silver perch foraging in oyster reef habitat were nearly double the estimates from control habitat. The results suggest restored oyster reefs influence habitat use and foraging behavior in species-specific manners, likely a result of differences in functional morphology and prey preference. Restored oyster reefs in the LRS likely act as valuable forage habitat for silver perch, an important trophic link in coastal and estuarine systems. Developing realistic estimates of fisheries production on a habitat-scale requires studying species-specific trophic dynamics. Empirical estimates of the processes contributing to production are necessary to better understand the functional role of restored oyster reefs in shallow estuarine and coastal systems, and the ecosystem services these reefs may provide.
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Denapolis, Tasia MV. "Legacy Habitat Suitability of eastern oysters (Crassostrea virginica) in Louisiana: a prelude to Mississippi River Delta freshwater diversions." ScholarWorks@UNO, 2018. https://scholarworks.uno.edu/td/2560.
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The Louisiana oyster industry is greatly impacted by freshwater and sediment diversions that are part of the effort to restore the state’s coastline. A habitat suitability index (HSI) proposes species-habitat relationships that can be instrumental in creating impact assessments and suitability predictions for management as new diversions are implemented. An oyster (Crassostrea virginica) HSI was developed using three variables crucial to oyster sustainability: average annual salinity, minimum monthly salinity, and average salinity during the spawning season. These Legacy HSI visualizations show annual fluctuations in the distribution of zones suitable for oyster cultivation prior to proposed diversions in Pontchartrain and Barataria Basins from 1967 to 2016. Modeling suitability based upon these variables can provide crucial information for timing the use of diversions to lessen harmful effects upon the oyster industry as well as indicate new potentially suitable areas that the diversions may create.
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Santopietro, George D. "Evolution of property rights to a natural resource: the oyster grounds of the Chesapeake Bay." Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/76496.
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Economists take an interest in property rights structures because of their importance in the definition of incentive structures. Fisheries have been analyzed as open access resources because they are not often organized around private property rights. The lack of private property rights though should not be taken to imply unlimited access. There is a need to differentiate between situations in which an institutional structure supports a system of common property rights from those in which access to a resources is truly limited.
In this study, a conceptual framework of the structure and workings of property rights to natural resources is developed. This includes a taxonomy of possible property rights structures that differentiates among types and degrees of common and private property. The study then compares and contrasts the differing views in the economics literature on the process by which property rights evolve.
This conceptual framework is used to develop a set of research questions that will structure the inquiry about the evolution of property rights to a specific natural resource, the Chesapeake Bay oyster grounds. The conventional and Institutionalist perspectives are related to fishery management policy and their differences assessed. The Institutionalist perspective is shown to raise questions about the historical development of property rights that would not be considered by conventional economists.
The resulting research questions are used to explain the economic history of the property rights to the Chesapeake Bay oyster grounds from 1607 to 1986. In Maryland and Virginia certain grounds of the Chesapeake Bay are reserved as a public oyster fishery, but, they have been regulated and managed by the states. In the history of the fishery, those who harvest from the public grounds have continually resisted the extension, or even encouragement of oyster cultivation on private leaseholds. The primary advocates of greater privatization of the bottoms have been economists and biologists. The governments of each state have chosen to maintain the commons in order to provide employment for watermen and to more widely distribute income among them.
The results of a survey of Virginia's oyster harvesters are presented. These provide further insights for discussing the role of the watermen in the evolution of property rights, and help to form conclusions on the future of the fishery. This case study leads to the discussion of conclusions on the theory of the economics of property rights.Ph. D.
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Jud, Zachary R. "Anthropogenic Disturbances in Estuarine Ecosystems: The Effects of Altered Freshwater Inflow, Introduction of Invasive Species, and Habitat Alteration in the Loxahatchee River, FL." FIU Digital Commons, 2014. http://digitalcommons.fiu.edu/etd/1197.
Full textAbstract:
With the majority of Earth’s population living in coastal areas, estuarine ecosystems have been particularly affected by anthropogenic disturbances. My dissertation research focused on three interrelated types of human disturbance that affect estuaries: Anthropogenic alteration of freshwater inflow, the introduction of invasive species, and habitat alteration. Using the LoxahatcheeRiver(Jupiter, FL) as a model system, my goal was to understand how these disturbances affect estuarine organisms, particularly fishes. One of the most ecologically harmful disturbances affecting estuaries is anthropogenic alteration of freshwater inflow (and resulting changes in salinity patterns). To identify effects of freshwater inflow on the behavior of an ecologically and economically important fish (common snook Centropomus undecimalis), I conducted a 19-month acoustic telemetry study. Common snook were more abundant and made more frequent upstream migrations during the wet season, but freshwater inflow did not appear to be the proximate cause for these behaviors. Increased estuarine salinity resulting from anthropogenic flow alteration may have facilitated the second type of disturbance that I address in this dissertation; the invasion of non-native Indo-Pacific lionfish into estuarine habitats. During the course of my dissertation research, I documented the first ever estuarine invasion by non-native lionfish. Using mark-recapture, I identified high site fidelity in lionfish, a trait that may aid future control efforts. The extremely low minimum salinity tolerance that I identified in lionfish appears to have allowed the species to colonize far upriver in estuaries with anthropogenically modified salinity patterns. Anthropogenic salinity alteration has also led to a severe degradation of oyster reef habitats in theLoxahatcheeRiver. As a foundation species, oysters provide food, shelter, and nursery habitat for a wide variety of estuarine organisms, including many ecologically and economically important fishes. Increasingly, degraded oyster reef habitats have been the focus of restoration efforts. I identified a relatively rapid (< 2 years) convergence between restored and natural oyster reef communities, and documented the importance of vertical relief in restoration success. My dissertation research is critical for the management and conservation of coastal rivers inFlorida, while more broadly informing restoration and management decisions in many other estuarine and coastal ecosystems.
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Machado, Ingrid Cabral. "Um retrato do extrativismo : a sustentabilidade na exploração comercial da ostra de mangue em Cananéia-SP." Universidade Federal de São Carlos, 2009. https://repositorio.ufscar.br/handle/ufscar/1649.
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Previous issue date: 2009-05-19Currently, the mangrove oyster Crassostrea sp. is one of the most important fishery resources exploited by the artisanal fishery setor of the Cananéia estuary, responsible for the livelihood of 60 families of extractivists for some decades. The production system can be characterized as rudimental, involving the extraction in mangrove and its direct marketing or previous fattening in structures like trays. The oyster is marketed exclusively in natura and depuration is the only form of improvement, involving a few extractivists. The socioecological system of the oyster extractivism has been target of several interventions, since actions promoted by government agencies, to organize the production chain, till external pressures, like the market ones, which act on the management and commercial practices, affecting the sustainability of the activity. The objective of the present exertion was from the study of characteristics, management and marketing practices of the oysters extractivists groups from Cananéia, to identify the factors that affect the sustainability and to provide subsides to support the management of the activity. For that the socio-economical and productive profile of the users was studied, and the production of oysters in Cananéia, the local commercialization processes, the natural stock of oysters and the productive areas were analyzed. The identified groups of extractivists were compared, and the trends relating to the sustainability of the activity in the ecological, economic, social, technological and ethical dimensions were analyzed. The Mandira group, beneficiary of a considerable number of public interventions, was the group whose performance in the analysis of sustainability was comparatively better. In the extreme opposite, the Porto Cubatão group presented the worst performance in almost all dimensions studied, a fact associated with the small group experience in the activity. As the Porto Cubatão group much as all others located in intermediate position, even though tend to sustainability in specific dimensions, are more susceptible to crises caused by unexpected changes in the system. In the Mandira group, in spite of a better structure, the progress is fragile and it is necessary to consolidate it. The social, technological and ethical dimensions had negative influence on the trends of sustainability and should be considered as priorities in the actions of management. The aspects identified as strategic to improve the possibilities of sustainability of the activity were: encouraging the "fattening" activity of fattening of oysters as well as the replacement of the forms of sale box and desmariscada by production of oysters in dozens ; limiting the entry to the activity; restrainting the illegal commercialization and the processing technology and expanding the user s participation in the management of the activity.
Atualmente, a ostra de mangue Crassostrea sp. é um dos mais importantes recursos explotados pelo setor pesqueiro artesanal do estuário de Cananéia, responsável pelo sustento de cerca de 60 famílias de extrativistas há algumas décadas. O sistema produtivo pode ser caracterizado como rudimentar, envolvendo a extração do recurso no mangue e sua comercialização direta ou a engorda prévia em viveiros tipo tabuleiro. O produto é comercializado exclusivamente in natura e a depuração é a única forma de beneficiamento existente, envolvendo poucos extrativistas.. O sistema socioecológico do extrativismo de ostras tem sido alvo de diversas intervenções, desde ações promovidas por órgãos públicos, no sentido de organizar a cadeia produtiva, até pressões de origem externa, como as de mercado, as quais atuam sobre as práticas de manejo e comercialização, afetando as tendências relativas à sustentabilidade da atividade. O objetivo do presente trabalho foi, a partir do estudo das caraterísticas e práticas de manejo e comercialização dos grupos de extrativistas de ostras de Cananéia, identificar os fatores que afetam a sustentabilidade e fornecer subsídios para apoiar a gestão da atividade. Para isso, o perfil sócio-econômico e produtivo dos extrativistas de ostras de Cananéia foi estudado, bem como foram analisados a produção de ostras do município, os processos comerciais desenvolvidos na cadeia produtiva local, o estoque natural do recurso e as áreas produtivas. Os grupos de extrativistas de ostras identificados foram comparados, sendo analisadas as tendências relativas à sustentabilidade da atividade nas dimensões ecológica, econômica, social, tecnológica e ética. O grupo do Mandira, beneficiário de um considerável número de intervenções públicas, foi o grupo cujo desempenho na análise de sustentabilidade foi comparativamente melhor. Como contraponto, o grupo do Porto Cubatão apresentou o pior desempenho em quase todas as dimensões estudadas, fato associado à pequena experiência do grupo na atividade. Tanto o grupo do Porto Cubatão, quanto os grupos situados em posição intermediária, ainda que em dimensões específicas tendam à sustentabilidade, apresentam maior susceptibilidade a crises provocadas por mudanças inesperadas no sistema. No grupo Mandira, apesar de melhor estruturado, os ganhos alcançados são frágeis, havendo a necessidade de avanços que os consolidem. As dimensões social, tecnológica e ética tiveram influência negativa sobre as tendências da sustentabilidade, devendo ser consideradas como prioritárias nas ações de gestão da atividade. Os aspectos identificados como estratégias específicas de ação para melhorar as perspectivas da atividade quanto à sustentabilidade foram o incentivo à atividade de engorda de ostras; a limitação do ingresso à atividade; o incentivo à substituição das formas de venda na caixa e desmariscada pela produção de ostras em dúzias ; a coibição do comércio clandestino e ampliação do alcance da tecnologia de processamento pós-colheita e da participação dos extrativistas na gestão da atividade.
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Millstein, Erika Shields. "Oyster reef restoration as a fisheries management tool." 2009. http://www.lib.ncsu.edu/theses/available/etd-08052009-145309/unrestricted/etd.pdf.
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Mitchell, Iona Margaret. "Relationship between water quality parameters (nutrients, seston, chlorophyll a), hydrodynamics and oyster growth in three major Pacific oyster (Crassostrea gigas) growing areas in southern Tasmania (Australia)." Thesis, 2001. https://eprints.utas.edu.au/20928/1/whole_MitchellIonaMargaret2001_thesis.pdf.
Full textAbstract:
An assessment was made of three Pacific oyster ( Crassostrea gig as) growing areas in
southern Tasmania (Pitt Water, Pipeclay Lagoon and Little Swanport) with respect to
water quality parameters, oyster growth and hydrodynamic characteristics. This was
done in an order to explain differences in reported oyster growth rates and hence address
the issue of shellfish productivity in each area. Water samples were collected monthly
for 13 months from several sites along the length of each area from a marine site to the.
upper reaches of the estuary, or coastal embayment. These were analysed for
chlorophyll a, nutrients (NOX, P04-P and Si04-Si), and seston quality and quantity (i.e.
total particulate matter (TPM) and particulate organic and inorganic matter (POM &
PIM)). Temperature, salinity and secchi disk depths were also recorded. Oyster growth
and condition were assessed from studies conducted over three consecutive periods at
two sites within each area. Hydrodynamic characteristics were calculated from tide
gauge data obtained. Additionally, a biodeposition study was conducted at one area
during two seasons to determine rates of deposition and composition of biodeposits.
Seston quantity was similar among areas, but seston quality, as expressed as %POM,
showed variation attributed to the characteristics of each area. Chlorophyll a
concentrations were generally low in each area, ranging from 0.2 to 4.0 μg L-1
.
Interestingly, chlorophyll a levels measured were high in winter to early spring months
within each area. Higher levels of chlorophyll a were measured following periods of
flooding and freshwater inflows, particularly in two of the study areas. Considerable
variation among areas was shown in oyster growth, with respect to shell length, width,
depth and live weight of oysters. Differences in growth are largely attributed to the
water quality and hydrodynamic characteristics noted within each of the areas. Mean
biodeposition rates varied from 39.6 g DW m-2 d-1 in winter to 180.5 g DW m-2 d-1 in
summer. The average organic content of biodeposits (approximately 19.2% POM) was
similar in summer and winter. The organic matter content of sediments under oyster
baskets was low(< 2.6 %), and it was concluded that biodeposits were being transported
and deposited elsewhere.
The overall findings from the study indicated that growth rates and productivity of each
area were largely influenced by the supply and availability of food. It appeared that stocking density and spatial arrangement of leases provided the greater limitation on
growth rate in Pitt Water and Pipeclay Lagoon. Little Swanport was characterised as
having the better growth rates and conditions for growth. Food quality, as measured by
chlorophyll a and %POM in particular, was higher than the other two sites, and flow
rates indicated that a greater quantity of food was reaching a larger proportion of the
cultured population. The marine nature of Pipeclay Lagoon suggested that the main
source of food supply to the cultured oyster population is of marine origin. However,
flow rates and transport of this material over the culture area is insufficient to provide
faster growth rates. Stocking density of oysters, and spatial arrangement of the culture
area, is most likely responsible for limitation on available food supply to the majority of
the population. Sufficient food is available for maintaining metabolic processes, but is
insufficient to enable greater storage and hence growth rates. Similar processes
appeared to be occurring in Upper Pitt Water, though it seems the greater fraction of
food is sourced from within the estuary, rather than being of marine origin. Sampling
during this study was fortunate to coincide with infrequent events of heavy and
prolonged rainfalls in the latter part of the year, resulting in flooding of this estuary.
The beneficial effects of this were elevated nutrient, chlorophyll a, seston levels and
greater increase in oyster dry meat weights, confirming the concerns raised by the oyster
farmers with respect to the negative effects of the Craigboume Dam.
Shellfish production estimates as used overseas were found to be not applicable to
Tasmanian conditions. Differences in culture environments between overseas oyster
growing areas and those found within Tasmania are discussed.
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Hanes, Samuel Paris. "The high modernist moment oysters, knowledge production, and conservation in the Progressive Era, 1878-1917." 2008. http://hdl.rutgers.edu/1782.2/rucore10001600001.ETD.17485.
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Barroso, Gilberto Fonseca. "Assessing the potential for mangrove oyster aquaculture in an estuarine system of the southeastern coast of Brazil : a geographic information system approach." 2004. http://hdl.handle.net/1828/648.
Full textAbstract:
Coastal aquaculture is among the fastest growing sectors of the food producing industry. Bivalve farming is a promising activity in low income countries were mollusk could be cultured under low technology and budget, contributing to reduce poverty and assuring food security. Site selection has been considered as a key process in successful aquaculture developments. A suitability model for mangrove oyster farming in the PiraquC-aqu/PiraquC-mirim estuarine system - PAPMES (Espirito Santo, Brazil) was developed. The suitability model is based on Multi-criteria Evaluation (MCE) which consists of selecting criteria, define their acceptable and optimum ranges, assign their weights of relative importance, and combine suitability criteria under a decision rule. A georeferenced database was created with 8 water quality variables considered related to the habitat requirements of mangrove oyster, with 19 field sampling campaigns on 6 samplings sites embracing an area of 51 lha. Low salinity and dissolved oxygen levels were detected in the upper estuarine sections. Using the geographic information system (GIs) Idrisi32, point data were converted to continuous surface models using secondorder polynomial fit. The normalization process aimed at standardizing the set criteria considering a single scale ranging from low (i.e., 0) to high suitability (i.e., 255). Through pairwise comparison technique weights were assigned to each criteria. Salinity and dissolved oxygen were considered the most important criteria because of their relationship to oyster short-term survival. A weighted linear combination and two constraints (i.e., fecal coliform > 43 MPN1100mL and navigation channel) were applied as the MCE decision rule. An area of 75ha (14.6% of the PAPMES) was considered constrained for mangrove oyster fanning. Two suitability models were performed using average and low salinity values. Suitability maps developed onto the 0 - 255 range were reclassified in 4 categories: unsuitable, moderately suitable, suitable, and very suitable. In both models, no area was indicated as unsuitable. Although the low salinity model could be considered more restrictive, it yielded a very suitable area 26% larger than the average salinity model. The combination of the two models could bring together risk taking and risk-averse perspectives, respectively. The output of such combination is a map locating 80ha of very suitable areas for mangrove oyster farming, with 9.5ha preferentially designated for intertidal farming using racks. Aquaculture zones are discussed in terms of their interactions with other systems at higher spatial scales, such as the watershed and the coastal zone. GIs can serve as an integrative environment to integrate complex variables in multiple scales. It is only through its integration in multisectoral development plans and programs for the watershed and coastal zone realms that coastal aquaculture will be recognized as sustainable enterprise.
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Sapna, V. "Investigation on the biochemical genetics of the Indian Pearl Oyster, Pinctada fucata (Gould)." Thesis, 1998. http://eprints.cmfri.org.in/16490/1/Thesis_1998_V.%20Sapna_Pearl%20Oyster.pdf.
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Suja, G. "Pathological investigations of Crassostrea madrasensis (Preston, 1916) in cultured and wild habitats from Southern India." Thesis, 2018. http://eprints.cmfri.org.in/13669/1/Suja%20G_2018_Thesis_Pathological%20investigations%20of%20Crassostrea%20madrasensis%20%28Preston%29.pdf.
Full textAbstract:
Edible oyster populations of the Indian coast are currently naive and
are not subjected to live introductions or trans-boundary movements. There
were no previous reports on edible oyster mortality due to disease out breaks in the country. Still, the major reported parasites in oysters over the
world have been observed in the present study within a low prevalence. The
two OIE listed pathogens, Bonamia ostrea and Marteilia refringens, the
protozoan, Perkinsus beihaiensis, the trematode, Bucephalus sp. and the
shell parasite Polydora sp. are those that have the potential to be a problem
for the future farming. Hence a comprehensive screening for pathogens in
other beds throughout the coastline is strongly recommended.
Presently oyster farming is getting popularized and is being extended
to more and more regions along the coast. At this stage, a good baseline data
on parasites and pathogens within natural environments is necessary for
proper disease management. The baseline data generated in this study will be
helpful for planning a health monitoring program in Crassostrea madrasensis
The farming site at Sathar Island was found to have the advantage of
producing oysters with high condition index and low incidence of parasites.
The duration of farming limiting to one year was found to be ideal since it
reduces the exposure period for parasite entry. But the presence of the major
protozoan parasites in the ecosystem should be considered while expanding
and intensifying oyster culture in future as the stressful condition can cause
parasitic proliferation in the ecosystem. A similar situation was observed in
mussel farming grounds along the west coast of India where a proliferation of
OIE listed protozoan, Perkinsus olseni was associated with intensification of
mussel culture. The nested primers developed for the major protozoan
parasites in this study can be used for screening the stocks for selecting brood
stock and for planning farming sites. As PCR screening using these primers is
more sensitive than the conventional methods, movement of infected stocks
to uninfected regions can be minimised based on this screening In conclusion, Crassostrea madrasensis stocks along the south
Indian coast (with respect to the stations studied) were found to be safe with
a low prevalence of pathogens. But, the comparatively higher burden of
parasites and pathological conditions observed in Tuticorin Bay indicates
the impact of contaminant exposure. Thus for maintaining the good health
status of oyster stocks, periodic surveillance and monitoring are necessary
and also the water quality should be regularly monitored for better control
over the chances of disease out breaks especially around the cultured areas.