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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.
1

An investigation into effective management structure for tuna resources in the West Indian Ocean

Edaly, Kevin January 1997 (has links)
Tuna fisheries in the coastal states of the West Indian Ocean (WIO) have been at the centre of the social, economic and political development of the region. Their significance in creating employment, providing food, and generating revenue for the people in the region cannot be overemphasized. To be able to derive full benefits from the tuna resources in the WIO, the coastal states will have to devise an efficient management strategy, not individually, but collectively. Currently, there is no such management structure in the region to accomplish this goal. This study is, therefore, an attempt to find some solution to this important issue, and to propose a suitable management framework that would guarantee an efficient and profitable tuna resource management mechanism in the region. To tackle this task, data were collected through documentary statistical sources as well as by the use of questionnaires. Information was received from many fisheries organisations, as well as from other international fishing institutions. The results show that there is an urgent need for a regional organisation to manage tuna resources in the WIO, in order to avoid overfishing and stock depletion which will have adverse consequences on the economic and development prospects of both the coastal states and distant water fishing nations (DWFNs) operating in the region. This study recommended the establishment of a "Regional Organisation for the Management of Tuna in the West Indian Ocean" (ROMTWIO) using a contingency-political model in recognition of the need for a systems organisational structure that reflects the political elements in the region. The organisation should address the issues of joint co-operation in self-determination and self-management of tuna resources in the region within the remit of existing international laws, and in recognition of the significant role other international bodies can play in the realisation of the benefits of a common tuna resources for all.
2

Modelling human wellbeing for fisheries management: Science, extraction and a politics of nature in the Walvis Bay, Namibia

Draper, Kelsey 03 September 2018 (has links)
Based in Walvis Bay, an industrial fishing town in Namibia on the west coast of southern Africa, this thesis argues that via the logic of neoliberalism, relations between scientific knowledge production, historical labour practices, and political decision-making emerge as a way of managing people and nature in uneven ways. Scientific modelling practices in the form of stock assessments, maintain traction as the technological solution for managing natural resource extraction in Namibia. As such, the dissertation explores the efficacy of computer models in the industrial fishing sector and considers how breakdowns between the scientific, social, and political knowledge worlds can be usefully brought into the conceptual model of the fishery for management. With a shift towards a more inclusive management framework that considers the policy issues as well as translating broad goals into measurable objectives, comes a shift in the logic of what fisheries management is meant to mediate and achieve. The logic is no longer as straightforward as producing an estimate of the amount of fishable biomass, but now must account for market conditions, changing technologies for fishing, and a changing climate and ecology. The human dimension is framed around the concept of wellbeing which in fisheries management emerges as an umbrella term for the social world that is reduced through the logic of neoliberalism to the measurable, enumerable, and indexable social and political implications of the use of Namibia’s natural resources. As one of few ethnographies of Namibia and the only one thus far to address the fisheries sector as a site of study, this dissertation investigates the increased dependence on scientific models in the Namibian hake fishery despite declining fish stocks and increased urban poverty and inequalities. The research contributes to the limited studies done on the political economy of Namibia and the rise of fish as national resource in the postcolony. It investigates the relations at risk in everyday life in Walvis Bay and re-imagines the framing of humans and nature for transformative practices of environmental and economic justice.
3

Social and economic factors influencing the emergence of collective action in a traditional fishery of Oman : an empirical assessment of three coastal fishing towns in south Al-Batinah

Al-Oufi, Hamed Said January 1999 (has links)
Overexploitation of many fish stocks underlines the need for more effort directed towards stock management so that the sustainability of resources is assured. To avert the tragic consequences of overfishing in coastal waters, a growing body of theoretical and empirical research provides evidence in support of cooperation among resource users to manage their commons. This study aimed to investigate the factors that contribute to the emergence and evolution of collective action in fishermen's communities to manage their coastal fish resources in South Al-Batinah, Sultanate of Oman. The study emphasises the importance of a collective action approach to fish resource management with examples from three fishing towns.In order to understand why fishermen choose to participate (or not to participate) in local collective action to manage fish resources, the researcher focuses on six main sets of issues that influence fishermen's decisions: economic factors; awareness of resource exploitation problems; institutional rules in use; social identity, group size and heterogeneity among resource users. Social and demographic factors as well as vessel configuration were also considered.Data collection for the study was carried out using three methods: questionnaire, semi-structured interview and observations of fishermen's activities. Statistical reports and other research papers carried out in Oman were also reviewed. The study found that there is a management institution that governs the fishing activities of the fishermen in the study area. Fishermen in the area inherited an indigenous management institution, which was established hundreds of years ago. It was also found that fishermen were very aware of the resource exploitation problems. High awareness of the resource exploitation problems coupled with high interdependence among users might induce them to work collectively to mitigate harm to their long-term welfare.The results of testing a number of hypotheses indicated that among the reasons which may influence collective action, are high economic dependence on the fishery,individuals' social identity as fishermen, awareness of the resources exploitation problems, risk aversion and heterogeneity (differences in objectives and interests).The study findings indicated that individuals using common resources are faced by various "assurance" and "chicken" problems. In both the PD game and the Assurance game, the preferred outcome is mutual cooperation. Whereas the predicted outcome of the former is defection, the latter suggests the possibility that the preferred outcome (i.e., cooperation) will occur, because individuals' decisions in the commons are influenced by a complex set of factors, rather than strictly materialistic self-interest. The analysis presented in this study examined several of those factors for their influence on individual behaviour. The findings of this study strongly suggest that the presence of local management institutions to coordinate the fishermen's activities in the study area is the key factor in avoiding the worst outcome (universal defection). The game structure has been changed from a Prisoner's dilemma to a Privileged game or a game of Chicken where the benefits from cooperation are maximized. It is the role of the institutions to determine how the cost of providing the public goods might be shared among participants.
4

Fisheries ecology of common wolffish, Anarhichas lupus, in the North Sea

Liao, Yih-Yia January 1999 (has links)
The common wolffish (Anarhichas lupus), a benthivorous species, is widely dispersed, although not abundant in the North Sea north of 54ºN latitude. Despite being widely distributed in sub Arctic and cold North Atlantic waters, little is known of the ecology of this species in the North Sea. This thesis aimed to provide ecological information for this species at the southern limit of its range in the Northeast Atlantic. North Sea common wolffish are regarded as sedentary in habit and mainly inhabited depths ranging from 60 m to 150 m. The bottom temperatures where this species were found in the North Sea ranged between 3ºC and 12ºC. The common wolffish is a by-catch species for the North Sea bottom trawl fishery. The long-term catch data and CPUE (catch per unit effort) indicated that the stock abundance of North Sea common wolfish has been decreasing over the last decades. However, it is suggested from VPA (virtual population analysis) and Yield-per-recruit analysis, that the North Sea common wolfish stock is still in a safe condition but has been overexploited. The means of total mortality (Z), natural mortality (M) and fishing mortality (F) of this species for 1996-1998 were 0.47, 0.17 and 0.30, respectively. Both resting metabolic rate (RMR) and maximum metabolic rate (MMR) were low for this species. RMR and MMR were measured for six adult common wolffish (mean weight, 1.39kg) at 5ºC and 10ºC. At 5ºC the mean RMR± SE was 12.18 ± 1.6 mgO(_2),kg(^-1)h(^-1), and mean MMR ± SE was 70.65 ± 7.63 mgO(_2)kg(^-1)h(^-1). At 10ºC the mean RMR±SE was 25.43 ±1.31 mgO(_2) kg (^-1)h(^-1), and mean MMR ± SE was 113.84 ± 16.26 mgO(_2) kg(^-1)h(^-1). Absolute metabolic scope was 53% greater at 10ºC than at 5ºC.The main food for common wolffish in the North Sea were Decapoda comprising 39 % of the overall diet by occurrence, with hermit crabs (Paguridae) being the dominant species. Other important dietary components were Bivalvia (20 %) and Gastropoda (12 %). Sea urchins (Echinidae), which are important prey of common wolffish in eastern Newfoundland, Gulf of Maine and Iceland, but typically of low energy value, occupied only 7 % of the diet. During the autumn/winter season, wolffish consumed less food compared with the remainder of the year. From this study, von Bertalanffy growth parameters for common wolffish in the North Sea were calculated to be: for male, L(_oo)= 111.2 cm, t(_o) = -0.43 and = 0.12; and for female, L(_oo)= 115.1 cm, t(_o)= -0.39 and K = 0.11, making North Sea common wolffish the fastest growing stock of this species reported. The fast growth of North Sea common wolffish may be a result of the higher energy content of the diet or greater metabolic scope available for food processing. This increased metabolic scope being associated with life in the warmer North Sea, in comparison to those stocks found elsewhere in the range of this typically sub-Arctic species. The maximum age found for this species in the North Sea was 18 years old. Median length at sexual maturity of male and female common wolffish is at 51.9 cm and 50.4 cm respectively, with the age of sexual maturity being achieved at 4-5 years in the North Sea. The spawning season of North Sea common wolffish is from October through to February. The fecundity varied with the body weight of females, from several thousand to 12,000 eggs. Ripe egg sizes ranged from 5 mm to 6.5 mm. Spermatozoa were found in mature male individuals throughout the whole year with the highest peak in October.
5

Studies on the coastal ecology and management of the Nabq Protected Area, South Sinai, Egypt

Galal, Nasser January 1999 (has links)
No description available.
6

Use of biomass model to asses species and productionprofile of marine cage culture in Taiwan

Huang, Wei-yu 14 August 2005 (has links)
Several species of fishes have been used for cage culture in Taiwan, including cobia, brown croaker, red drum, grouper, red seabream, emperor and snapper. Roughly speaking, the main factors determining the choice of the target species are mainly the selling price deleting the production cost. Different species have different biological characteristics that affect the economical performance. Included were specific growth rates, death or survival within cultural period, and efficiency in food conversion, etc.. By employing and modified the so-called Biomass model used in fishery biology (Kings, 1995), this research integrates the above factors into one single spreadsheet for each individual species, allowing for systematic observation of the continuous change in level of production (in terms of biomass). Through the culturing period, degrade in number was gradually offset by the gain in averaged body weights until a maximum value is reached before going downhill. This gives rise to the optimal solution of yield with the respective culturing period thus required. The results for different species were further compared in terms of expected investment and return by the end of the production. Results from this study showed that cobia has more advantage (in terms of biomass, biovalue and return on investment) than others as the prior choice under the current situation. Basic information for this study included the value of natural mortality, length-and-weigh relationship and the growth equation of the target species. The system was programmed under the EXCEL-Spreadsheet system of the Microsoft Inc. In the future other species of fishes may also be tested as possible candidates for cage culture. The program could also expected to serve as an auxiliary tool in education and fishery extension services.
7

SAUGER POPULATION DEMOGRAPHICS, EVALUATION OF HARVEST REGULATIONS AND POPULATION CONNECTIVITY IN LARGE MIDWESTERN RIVERS

Yallaly, Kasey L 01 August 2018 (has links)
Sauger Sander canadensis are a native top level predator and popular sport fish. They are native to large, turbid midwestern rivers and are a highly migratory species that relies on unrestricted access to specific habitats throughout their lifespan. Due to specific habitat requirements and popularity as a sport fish, Sauger are in decline across much of their range. Habitat alterations including barriers, channelization and sedimentation, as well as overharvest, have resulted in population declines. Sauger are often subject to relatively high levels of exploitation because of their tendency to concentrate below dams during migrations, which leaves them vulnerable to anglers. The lower Kaskaskia River below Carlyle Lake dam and the lower Ohio River contain important Sauger sport fisheries despite the presence of multiple dams on both rivers and the potential for high levels of exploitation. However, effects of current and potential harvest regulations on Sauger stocks in the Kaskaskia and Ohio rivers have not been assessed. From previous annual monitoring surveys, Sauger in the Ohio and Kaskaskia rivers have very different size and age structures and are managed under different regulations. Additionally, the Kaskaskia River and its largest reservoir (Carlyle Lake) are stocked annually with Sauger, but the contributions of stocked Sauger and immigrants from the Mississippi River to the Kaskaskia River Sauger stock are unknown. I first sought to assess population demographics of Sauger in the Kaskaskia and Ohio Rivers to gain a baseline understanding of both populations and then used these data to evaluate harvest regulations on each river. This objective tested the null hypothesis that no differences in recruitment indices, growth rates and mortality rates exist between Sauger populations within each river. Sauger in the Kaskaskia River are currently managed under a 356-mm minimum length limit and a 6-fish daily bag limit. Prior to 2018, the lower Ohio River was managed under no minimum length limit and a 10-fish daily bag limit. To assess the contribution of Sauger from different environments to the Kaskaskia River stock, I used otolith microchemistry to infer recruitment sources of fish and assess movement of fish between the Kaskaskia and middle Mississippi rivers. This objective tested the null hypothesis that no difference existed in the contribution of different rivers to the Kaskaskia River sauger population. The Ohio River Sauger population had a small age and size structure relative to the Kaskaskia River. Sauger from each river exhibited fast growth rates and high annual mortality. Population modeling indicated that the current 356-mm minimum size limit for Sauger in the Kaskaskia River is sufficient at preventing growth overfishing and is likely resulting in the larger size structure compared to the Ohio River. Sauger were likely experiencing growth and recruitment overfishing in the Ohio River under no minimum length limit and will likely benefit from the 356-mm minimum length limit implemented in 2018. Otolith microchemistry revealed that Sauger from the Mississippi River represented a small contribution to the Kaskaskia River Sauger stock; however, some fish showed evidence of moving between the Kaskaskia and Mississippi rivers. Similar water chemistry between the hatchery and Carlyle Lake prevented the identification of hatchery origin Sauger. Because the Sauger stock in the Kaskaskia River appears to be primarily supported by stocking of fish into Carlyle Lake or natural reproduction within the Kaskaskia River, fisheries managers should focus on quantifying the contribution of hatchery fish to the Kaskaskia River stock.
8

Assessing the implementation efficacy of an ecosystem approach to Fisheries management in the South African sardine fishery

McGregor, Emily Skye January 2015 (has links)
Includes bibliographical references / An Ecosystem Approach to Fisheries management (EAF) offers a holistic approach for sustainable fisheries management by extending the traditional target resources-orientated management (TROM) to include wider social-ecological dimensions of fisheries. An EAF requires balancing of multiple, often conflicting objectives, effectively dealing with complexity and uncertainty, and engaging with diverse groups of stakeholders. Various tools within the field of Multi-criteria Decision Analysis provide a formal approach which takes explicit account of multiple criteria, while effectively dealing with risk and uncertainty. A knowledge-based tool was developed in this thesis to assess the efficacy of EAF implementation for the ecological well-being dimension in the South Africa sardine fishery. An iterative, participatory approach was adopted for its implementation. The modelling philosophy applied a rapid prototyping approach, and an applied research perspective was employed to direct the research. A broad group of stakeholders participated in indicator selection, tool design, and interpretation. The knowledge-based tool provided a hierarchical framework for seven specific management objectives to which eleven ecological indicators were linked. Time series (1987-2009) were collated for each indicator, and a utility approach was used to transform indicators to a common scale. Weights for indicators and objectives were agreed to by stakeholders and combined through the objectives' hierarchy using weighted means. The resulting outputs were discussed in detail during focus group meetings to ensure that the tool was clearly presented and as intended helped improve the stakeholder's understanding of the process. It was confirmed that the 20 knowledge-based tool presents a transparent, repeatable and scientifically defensible approach, suitable to meet management requirements. The tool development process was useful in bringing diverse stakeholder groups together, and through applying the tool as a boundary object, has helped to bridge the boundary between the TROM and EAF research communities. Encouraging stakeholder interaction offers opportunities for social learning, which if carefully facilitated through the tool development process is likely to enhance the outcomes of this process and support more generally in bridging boundaries to EAF implementation. The combined focus on tool development and social processes supports effective implementation of an EAF in the South African small pelagic fishery and provide a model for other fisheries.
9

Pisces: a computer simulator to aid planning in state fisheries management agencies

Clark, Richard Dean 15 July 2010 (has links)
Some fisheries management activities have clearer relationships with angler consumption than others, end the clarity is usually reflected by the amount of historical data available upon which to base the relationship. Adequate historical data exists to derive the relationships between angler-days and access development, water development, regulation changes, and catchable trout stocking, so these relationships are probably the most reliable in PISCES. Little historical data exists to assess the effects of research and information and education activities upon angler-days. Therefore, the segments of PISCES accounting for research and information and education are probably the least reliable parts of the model. PISCES can be improved before it is utilized in decision analysis. First, the efficiency of the computer program could be improved. PISCES is functional, but computer time and storage space might be saved by altering the program. Second, sensitivity analysis of input variables would provide important information to future users of PISCES. And finally, an application study would reveal any unforeseen problems which might arise in using PISCES. If PISCES is never used to formulate management decision policies, it is hoped that some of the modeling techniques employed will prove useful in future efforts to model natural resource systems. / Master of Science
10

Effect of Water Temperature, Angling Time, and Dissolved Oxygen Concentration on the Survival of Angled and Tournament-Handled Largemouth Bass

Keretz, Kevin Randy 08 December 2017 (has links)
Largemouth Bass Micropterus salmoides is the most sought after species by recreational anglers in the United States. Survival of angled and tournament-handled Largemouth Bass is related to numerous factors; however, the independent effects of water temperature, angling time, and live well dissolved oxygen concentration on survival have not been measured. Survival was evaluated in simulated catch and release and tournament trials over the range of temperatures encountered by Largemouth Bass anglers (17-33°C) while also testing independent effects of angling time, live well temperature, and live well dissolved oxygen treatments. Caught-and-released Largemouth Bass experienced 100% survival at temperatures ≤33°C after 1 minute of angling, but survival decreased with additional angling time. Survival declined in tournament-handled fish at 33°C; however, high survival was shown to be possible at ≤29°C after 1-minute angling time, confinement in live wells containing less than ambient temperatures and dissolved oxygen ≥5.5 mg/L, and organized in-water weigh-in procedures.

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