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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

A nutritional approach to reduce phosphorus pollution in hatchery effluent /

Skonberg, Denise. January 1997 (has links)
Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (leaves [164]-176).
12

Off the grid eco-friendly industry /

Bally, Todd. January 2009 (has links)
Thesis (M.Arch.)--University of Detroit Mercy, 2009. / "24 April 2009." Includes bibliographical references (p. 101).
13

A conceptual model of groundwater flow at the midway, Utah fish hatchery as constrained by geochemical, physical hydrogeological, and geophysical methods /

Durrant, Camille. January 2005 (has links) (PDF)
Thesis (M.S.)--Brigham Young University. Dept. of Geology, 2005. / Includes Bibliographical Information (leaves 22-24).
14

Growth, incidence of bacterial kidney disease and immunological function of salmonids reared in captivity

Mazur, Carl François January 1991 (has links)
Pacific salmon reared commercially off of the Coast of British Columbia suffer great mortality losses to Bacterial Kidney Disease (BKD), caused by the diplobacillus bacterium Renibacterium salmqninarum. This thesis investigates the effects of environmental conditions on the growth performance and disease susceptibility of salmonids reared in captivity. I found that growth rate of chinook salmon was significantly higher in fish fed to 100 compared to 67 % of satiation during the first 175 days of saltwater rearing but not during the first winter. Feed coversion rate was significantly higher for fish fed at 100 % of satiation compared to 67 % of satiation and higher during the winter compared to summer and fall, irrespective of feeding level. Mortality rates were significantly higher during the summer than during the fall or winter, irrespective of experimental treatment. The last BKD sampling period (day 263) revealed that infection rates were directly proportional to stocking densities of 1.5 to 4 kg.m⁻₃. Hatchery-reared chinook salmon held in freshwater aquaria had significantly lower hematocrit and plasma cortisol concentration increases in response to increased stocking density than did their wild counterparts. Crowding of hatchery-reared and wild chinook salmon resulted in equally increased mortality rates for both groups of fish. Day 33 plasma cortisol concentrations in Atlantic salmon held at three stocking densities were directly proportional to stocking densities of 8 to 64 kg.m⁻₃. The ability of anterior kidney lymphocytes from these fish to produce antibody-producing cells was inversely proportional to the density at which the fish were held. / Land and Food Systems, Faculty of / Graduate
15

Evaluation of Wildlife Depredation at Fish Hatcheries in the Intermountain West

Pitt, William C. 01 May 1995 (has links)
During 1993- 1994, I investigated wildlife depredation at Intermountain West fish hatcheries to quantify losses, determined the reliability of bioenergetics models and hatchery manager perceptions to predict losses, and investigated the effectiveness of simple control measures. I observed predators and surveyed managers to quantify the extent of depredation losses and to identify the species responsible. Great blue herons (Ardea herodias), black-crowned night herons (Nycticorax nycticorax), ospreys (Pandion haliaetus), and California gulls (Larus californicus) were the most significant predators of hatchery fish in the field study, and were perceived as such by hatchery managers. Losses to avian predators at two hatcheries were 7.0% and 0.6% of annual production based on my observational data, but hatchery managers believed depredation losses were 15% at each hatchery. I estimated the consumption of rainbow trout (Oncorhynchus mykiss) by great blue herons using bioenergetics models of existence metabolism, existence metabolism plus reproductive costs, and field metabolic rate. compared the model-based predictions to observed consumption rates of free-ranging herons foraging at a fish hatchery. The fish consumption predicted by the existence metabolism model and observed consumption were similar from October- June. During the breeding season, observed consumption was higher than consumption predicted by the existence metabolism model but lower than that expected from the energy requirements for breeding individuals. This result was expected given that only a portion of the bird population was breeding. Although consumption predicted by the field metabolic rate differed significantly from observed consumption for more months than the existence metabolism models, predicted annual consumption from field metabolic rate and observed annual consumption were not signliJcantly different (.E < 0.05). Peak observed consumption occurred during August and September and was predicted by the model. Performance of the three models may be improved with estimates of population structure and more reliable population estimates. I evaluated the effectiveness of perimeter fencing in reducing heron depredation on fish raised in concrete raceways at a trout hatchery in Midway, Utah. Fences were constructed of single-strand monofilament line placed 20 cm above raceway walls. Fences had no impact on the number of birds foraging or their fish consumption rate.
16

Production economics of summer flounder Paralichthys dentatus aquaculture in a recirculating system /

Yates, J. Kevin. January 2004 (has links) (PDF)
Thesis (M.S.)--University of North Carolina at Wilmington, 2004. / Includes bibliographical references (leaves : 53-58).
17

Modeling thermal environment of a recirculating aquaculture system facility

Singh, Sahdev 30 December 2008 (has links)
Economic viability of fish production in recirculating aquaculture system (RAS) facility depends on minimizing the energy requirements of operating such facilities. The fish growth and water quality aspects of RAS have been studied in considerable details. However, the understanding of the thermal environment of RAS lags behind. A step-wise steady-state thermal model was developed to simulate the daily heating, ventilation, water pumping, biofilter operation, and lighting energy requirements over a production cycle. The model was validated using temperature and energy data collected from RAS facility of Virginia Tech during 1992. Model simulations were performed with various production scenarios. The energy cost of fish production ($/kg) was used to evaluate different scenarios with and without heat recovery from discharged system water. Building heating required the most (40 % - 70 % of total) energy followed by water pumping, biofilter operation, lighting, and ventilation. Water replacement was the most dominant factor in determining the facility’s heating energy requirement. Heat recovery from discharged system water indicated significant drop (up to 40 %) in energy cost of fish production. / Master of Science
18

Genetic management of Atlantic cod (Gadus morhua L.) hatchery populations

Herlin, Marine Claire Ghislaine January 2007 (has links)
Intensive aquaculture of Atlantic cod is fast developing in both Northern Europe and Canada. The last six years have seen major improvements in the larval rearing protocols and husbandry techniques for this species. Although breeding programmes are currently being developed by both governmental and private institutions in the main cod producing countries (i.e. Norway, Iceland and Canada), most hatcheries still rely on the mass spawning of their own broodstock. Mass spawning tanks are complex systems where fish are left to spawn naturally and fertilised eggs are collected with the overflowing water, with little or no control over the matings of the animals. Few published studies in other commercial marine species (i.e. turbot and sole) have attempted to analyse the output from such systems using microsatellite markers and several parentage analysis software programs. A review of these publications exposed a lack of consistency in the methods used to analyse such complex datasets. This problem was addressed by carrying out a detailed comparison of two analytical principals (i.e. assignment by strict exclusion and assignment by probabilities) and four parentage software programmes (i.e. FAP, VITASSIGN, CERVUS and PAPA), using the DNA profiles, at 5 loci, from 300 cod fry issued from the mass spawning of a large hatchery cod broodstock tank (consisting of 99 fish). This study revealed large discrepancies in the allocation outcomes between exclusion-based and probability-based assignments caused by the important rate of typing errors present in the dataset. Out of the four softwares tested, FAP (Taggart, 2007) was the most appropriate to use for handling such a dataset. It combined the most conservative method of assignment with the most informative output for the results displayed. In an attempt to study the breeding dynamics in a cod commercial hatchery, parental contributions to five groups of 300 fry (from five single days of spawning and from two commercial mass spawning cod tanks) were analysed, based on the genotyping data from eight loci. The parentage results from the exclusion-based analyses revealed that, on a single day, at least 25 to 30% of the total breeding population contributed to fertilised eggs that resulted in viable offspring at 50 and 83 days post-hatch. Family representations were highly skewed - with the marked dominance of a few males - and effective breeding populations were consistently low (approx. 5% of the total breeding population). Parental contribution to a group of 960 codlings - produced following intensive commercial practices (i.e. including successive size gradings and mixing of batches) and belonging to a single graded group - was also analysed, based on the genotyping data from eleven loci. The effective breeding population size of the juvenile batch (c. 14% of the total broodstock population) was two to three times greater than the effective size observed on a single day of mass spawning. The per-generation rate of inbreeding was however relatively high, for this batch alone, at 2.5%. Based on these results, suggestions were made to manage hatchery cod broodstock populations and implement genetic selection. Early maturation of farmed cod in sea cages (at two or three years old) is a major concern for ongrowers. Understanding the mechanism(s) behind sex determination in cod would probably help the development of a method to control sexual maturation. In an attempt to elucidate sex determination in cod, a protocol to induce gynogenesis was developed. Gynogenetic fish were successfully produced by irradiating cod milt with UV and applying a cold shock (at -6oC) to newly fertilised eggs. However, due to poor survival during larval rearing, only one gynogenetic fish survived long enough to be sexed; not enough to conclude anything on the sex determination mechanism(s) in cod.
19

Staff responses to implementing environmentally sustainable change at federal fish hatcheries in BC

Krause, Wayne Edward 21 March 2011 (has links)
Anecdotal information indicates a resistance to change from federal fish hatchery staff regarding environmentally sustainable infrastructure renewal and hatchery operations. Qualitative research was conducted to investigate this phenomenon, using face-to-face interviews with nine hatchery staff across British Columbia. The interviews were audiotaped and transcribed verbatim, and participants‘ responses remained confidential, due to the relatively small hatchery community. Responses were grouped under two headings, Barriers to Change and Embracing Change, and four distinct themes emerged: Governance, Benefits, Education and Research, and Culture and Personal Beliefs. Barriers to change related to governance emerged as the dominant theme during interviews. This research examines the culture of hatcheries and their perceived governance structure, identifies barriers to implementing change, and makes recommendations to foster effective governance. Characterizing hatchery staff responses to change is a significant step in moving towards environmentally sustainable infrastructure renewal and environmentally sustainable program operations.
20

A strategy towards improved fish hatchery management in Northeast Thailand

MacNiven, Angus M. January 2005 (has links)
This report addresses the problem: how to improve approaches to fish seed production in smallholder aquaculture systems of Northeast Thailand? The work was carried out as a component of the U.K. Government Department for International Development Aquaculture Research Programme funded project, R7052: Improving freshwater fish seed supply and performance in smallholder aquaculture systems in Asia. From 1997 to 2003 the project worked in collaboration with regional partners in Bangladesh, Laos P.D.R., Thailand and Vietnam on constraints to seed production and distribution. The research problem called for improvement, implying that change was required in the way that seed was produced. The hypothesis that active collaboration in research by seed producers and institutional partners, facilitated by project staff would enable all participants to extend their understanding of the situation, contribute to the knowledge base and that resulting accommodations would lead to a continuous process of planning, action and reflection toward changes required for improvement. Reflection on the project outputs indicated that quality of fish seed was variable but there was no agreement on the nature of the problem among stakeholders. The decision was made to shift the research focus away from looking for technical problems and to focus instead on examining ways that existing knowledge could be integrated in a learning process with key stakeholders. The research problem then became to find an appropriate, effective and efficient methodology to achieve this; participatory action research was chosen for evaluation. Participatory action research is a collaborative approach involving the researcher in a facilitative role working with stakeholder groups to enable systematic investigation of issues, planning and action to resolve the issues. Outcomes should be action and public knowledge that feed in to further reflection and action in an ongoing learning cycle. Implementation of the methodology was carried out over two stages; the first planned set of activities involved extension of the existing collaborative arrangement with the Thai Government Department of Fisheries (DoF) and the Asian Institute of Technology Aqua Outreach Programme (AOP) in order to prepare a field research team and plan for field activities. The second stage was participatory action research field work which involved invitations to collaborate being extended to four formal groups and one informal group of hatchery operators in two Provinces of Northeast Thailand. Research facilitated by the research team used a range of participatory methods for identification and prioritisation issues, analysis, action planning, monitoring and evaluation. Actions were supported by the project logistically and financially. The exploratory approach to project planning meant that monitoring processes was as important as monitoring specific indicators. The output of the first set of activities was a formal agreement to collaborate however the strength of the collaboration was indicated by the low level of commitment shown by the DoF and AOP representatives in planning and team building. The lack of commitment had important implications for impact and sustainability of the research. Greater attention to the partnership process was an important lesson. Four of the hatchery operators’ groups approached accepted the invitation to collaborate with the project. This collaboration resulted in a range of knowledge outcomes, the development of social relations horizontally within the hatchery groups and vertically to include individuals from service providing agencies in the local administration. Participatory evaluation by participants and the DoF partners was positive. Evaluation of the project indicated that the approach was; appropriate in terms of the needs of primary stakeholders, the requirements of the donor and the circumstances under which it was carried out; effective in achieving knowledge outcomes that contributed to gains in livelihood assets for participants but ineffective in influencing the policies, institutions and processes that would have ensured sustainable impact from the collaboration as a result of the shortcomings in the institutional partnership arrangements; efficient in terms of resource use to obtain outputs and also in emergence of lessons to inform future practice.

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