Abalone stock enhancement at Cape Recife, Eastern Cape Province of South Africa
- Authors: Witte, Warren
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/45695 , vital:25532
- Description: The potential for restocking depleted natural reefs with hatchery abalone, Haliotis midae, to support a commercial ranching venture in the Eastern Cape Province of South Africa was investigated. A baseline stock assessment and analysis of historical fishery data provided compelling evidence of significant declines in the abalone stock, attributed to uncontrolled illegal fishing over the last 20 years at the study site. A ranching pilot study was undertaken where small-scale replicated seeding experiments were set up which quantified the effect of seed size, density and habitat on survival and growth of hatchery-reared abalone. Thirty-six experimental plots were seeded with 8400 abalone spread evenly over two broad habitats. Mean retrievals of seeded abalone were 17% ranging from 4 - 42% after a minimum of eight months at large. Release density and large-scale habitat had no significant effect on seed survival, but smaller seed size (40.0 ±3.7mm shell length) achieved higher (F1, 22 = 4.64, p = 0.042) retrievals than larger seed size (53 ±3.7mm). Growth rates were an average of 30% higher in the shallow sites compared deeper sites (t1, 1091 = -2.79, p = 0.005). There was seasonal component in growth with a 0.55 ± 0.04 mm per month higher rate in summer than during winter (t1, 1091 = -12.45, p < 0.001). Abalone seed releases were also conducted on a larger scale, which focused on the economic potential for commercial-scale ranching. Over 160 sites were seeded with 1.4 million hatchery reared abalone or 30 metric tonnes. Seventeen sites underwent long-term monitoring of survival with repeated sampling events on sites over a period of up to 666 days. Nine of these sites were seeded with 140800 small abalone (29 – 40 mm), three sites with 25100 medium abalone (30 – 46 mm) and five sites with 14700 large abalone (60 – 84 mm). There was a significant difference in survival between the seed sizes (F4,6329 = 304.3, P < 0.001). The Generalized Linear Mixed Model (GLMM) calculation estimated the instantaneous apparent mortality rate for small, medium and large abalone at 1.19 yr-1 , -0.9 yr-1 and -0.67 yr-1 , which equated to a survival rate of 21%, 28% and 36% per year respectively. The weighted mortality rate calculated according to the seed size differential mortality and the number of seed released for those sizes was 1 yr-1 or 25% survival. In conjunction with a conservative somatic growth rate of 1.2mm.m-1 and plausible emigration rates, a range of biomass harvesting estimates were obtained. Movement and mortality were investigated using video analysis which showed that hatchery seed had the ability to move considerably once released onto natural reefs and confirmed that mortality immediately following releases was due to the heavy predation pressure as confirmed by shell collections. This project has demonstrated that potential exists for ranching in South Africa and highlights critical factors that need to be addressed if ranching is to be an economically viable operation.
- Full Text:
- Authors: Witte, Warren
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/45695 , vital:25532
- Description: The potential for restocking depleted natural reefs with hatchery abalone, Haliotis midae, to support a commercial ranching venture in the Eastern Cape Province of South Africa was investigated. A baseline stock assessment and analysis of historical fishery data provided compelling evidence of significant declines in the abalone stock, attributed to uncontrolled illegal fishing over the last 20 years at the study site. A ranching pilot study was undertaken where small-scale replicated seeding experiments were set up which quantified the effect of seed size, density and habitat on survival and growth of hatchery-reared abalone. Thirty-six experimental plots were seeded with 8400 abalone spread evenly over two broad habitats. Mean retrievals of seeded abalone were 17% ranging from 4 - 42% after a minimum of eight months at large. Release density and large-scale habitat had no significant effect on seed survival, but smaller seed size (40.0 ±3.7mm shell length) achieved higher (F1, 22 = 4.64, p = 0.042) retrievals than larger seed size (53 ±3.7mm). Growth rates were an average of 30% higher in the shallow sites compared deeper sites (t1, 1091 = -2.79, p = 0.005). There was seasonal component in growth with a 0.55 ± 0.04 mm per month higher rate in summer than during winter (t1, 1091 = -12.45, p < 0.001). Abalone seed releases were also conducted on a larger scale, which focused on the economic potential for commercial-scale ranching. Over 160 sites were seeded with 1.4 million hatchery reared abalone or 30 metric tonnes. Seventeen sites underwent long-term monitoring of survival with repeated sampling events on sites over a period of up to 666 days. Nine of these sites were seeded with 140800 small abalone (29 – 40 mm), three sites with 25100 medium abalone (30 – 46 mm) and five sites with 14700 large abalone (60 – 84 mm). There was a significant difference in survival between the seed sizes (F4,6329 = 304.3, P < 0.001). The Generalized Linear Mixed Model (GLMM) calculation estimated the instantaneous apparent mortality rate for small, medium and large abalone at 1.19 yr-1 , -0.9 yr-1 and -0.67 yr-1 , which equated to a survival rate of 21%, 28% and 36% per year respectively. The weighted mortality rate calculated according to the seed size differential mortality and the number of seed released for those sizes was 1 yr-1 or 25% survival. In conjunction with a conservative somatic growth rate of 1.2mm.m-1 and plausible emigration rates, a range of biomass harvesting estimates were obtained. Movement and mortality were investigated using video analysis which showed that hatchery seed had the ability to move considerably once released onto natural reefs and confirmed that mortality immediately following releases was due to the heavy predation pressure as confirmed by shell collections. This project has demonstrated that potential exists for ranching in South Africa and highlights critical factors that need to be addressed if ranching is to be an economically viable operation.
- Full Text:
Beyond War, Violence, and Suffering: Everyday Life in the Honde Valley Borderland Communities during Zimbabwe’s Liberation War and the RENAMO Insurgency, c.1960-2016
- Authors: Nyachega, Nicholas
- Date: 2017
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/7023 , vital:21210
- Description: This thesis examines the history of the Honde Valley area, in Mutasa District, along the Zimbabwe-Mozambique border. It uses two historic developments: the Zimbabwe liberation war and RENAMO insurgency to explore daily life and mundane experiences of the borderland communities, mainly from the late 1970s to 2016. Because earlier historians of these two historic developments have been much interested in studying the aspects of violence and suffering, this study extends the focus of analysis to the mundane experiences. I argue that in borderland areas, there are other wartime aspects of life worth investigating other than violence and suffering. In doing so, the thesis deploys the notions of conviviality and the everyday to understand the daily experiences of the Honde Valley communities during the disruptions caused to everyday life by these wars. Admittedly, twentieth century wars in Zimbabwe and Mozambique transformed the area that had previously remained at the fringes of colonial power from 1890-1950, into a new and bitterly contested ‘sharp end’ of the war. Nonetheless, peoples’ experiences during these wars cannot be understood merely in relation to violence and suffering. Furthermore, I argue that although some families were forcibly moved into liberation war “Protected Villages ”, they innovatively designed new mechanisms and alternative lifestyles in response to the state’s routinised control. The thesis concludes that beyond the confines of war-induced violence and suffering, Honde Valley communities used their borderland location to evade the pressures of war and continued with life.
- Full Text:
- Authors: Nyachega, Nicholas
- Date: 2017
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/7023 , vital:21210
- Description: This thesis examines the history of the Honde Valley area, in Mutasa District, along the Zimbabwe-Mozambique border. It uses two historic developments: the Zimbabwe liberation war and RENAMO insurgency to explore daily life and mundane experiences of the borderland communities, mainly from the late 1970s to 2016. Because earlier historians of these two historic developments have been much interested in studying the aspects of violence and suffering, this study extends the focus of analysis to the mundane experiences. I argue that in borderland areas, there are other wartime aspects of life worth investigating other than violence and suffering. In doing so, the thesis deploys the notions of conviviality and the everyday to understand the daily experiences of the Honde Valley communities during the disruptions caused to everyday life by these wars. Admittedly, twentieth century wars in Zimbabwe and Mozambique transformed the area that had previously remained at the fringes of colonial power from 1890-1950, into a new and bitterly contested ‘sharp end’ of the war. Nonetheless, peoples’ experiences during these wars cannot be understood merely in relation to violence and suffering. Furthermore, I argue that although some families were forcibly moved into liberation war “Protected Villages ”, they innovatively designed new mechanisms and alternative lifestyles in response to the state’s routinised control. The thesis concludes that beyond the confines of war-induced violence and suffering, Honde Valley communities used their borderland location to evade the pressures of war and continued with life.
- Full Text:
Help or hindrance? a critical analysis of the agreement on sanitary and phytosanitary measures, and its effects on developing countries
- Authors: Waterworth, Tayla
- Date: 2017
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: http://hdl.handle.net/10962/7090 , vital:21216
- Description: WHILE it is accepted that the category of "developing country" is a broad one, it can nevertheless be acknowledged that the countries which fall within this categorisation share several common features. Such common features include their lack of financial resources and scientific capacity, and their reliance on trade in primary agricultural goods. The Agreement on Sanitary and Phytosanitary Measures was originally created to regulate trade in primary agricultural goods, and so its provisions are of great significance to developing countries. In its Preamble the Agreement acknowledges both the unique circumstances of developing countries and its desire to assist them in entering into and expanding within the international trading markets. As part of this endeavour, several provisions were included in the Agreement which purport to protect and provide for the interests of developing countries. In its inception, its Preamble, and the very nature of its content, the Agreement shows a desire to assist developing countries wherever possible. Unfortunately, a close analysis of the provisions of the Agreement shows that this desire has not been fulfilled. Many of the provisions of the Agreement are heavily skewed toward the interests of importing Members, often at the expense of developing Members - particularly those that export primary agricultural goods. Even the provisions of the Agreement which purport to provide protection and special and differential treatment specifically for developing countries frequently fall short, either as a result of ambiguous phrasing or poor textual interpretation by the dispute settlement bodies of the World Trade Organization. As a result, there exists a potential within the Agreement to have a significant detrimental impact on the international trading opportunities of exporting developing countries. In this thesis I analyse the provisions of the Agreement to determine where, why and how they are likely to have, or are having, a detrimental impact on developing countries (particularly exporting developing countries). After identifying these problems I examine and discuss several potential solutions and how they may be implemented to minimise - or even remove - the negative impact on developing countries and their international trading markets.
- Full Text:
- Authors: Waterworth, Tayla
- Date: 2017
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: http://hdl.handle.net/10962/7090 , vital:21216
- Description: WHILE it is accepted that the category of "developing country" is a broad one, it can nevertheless be acknowledged that the countries which fall within this categorisation share several common features. Such common features include their lack of financial resources and scientific capacity, and their reliance on trade in primary agricultural goods. The Agreement on Sanitary and Phytosanitary Measures was originally created to regulate trade in primary agricultural goods, and so its provisions are of great significance to developing countries. In its Preamble the Agreement acknowledges both the unique circumstances of developing countries and its desire to assist them in entering into and expanding within the international trading markets. As part of this endeavour, several provisions were included in the Agreement which purport to protect and provide for the interests of developing countries. In its inception, its Preamble, and the very nature of its content, the Agreement shows a desire to assist developing countries wherever possible. Unfortunately, a close analysis of the provisions of the Agreement shows that this desire has not been fulfilled. Many of the provisions of the Agreement are heavily skewed toward the interests of importing Members, often at the expense of developing Members - particularly those that export primary agricultural goods. Even the provisions of the Agreement which purport to provide protection and special and differential treatment specifically for developing countries frequently fall short, either as a result of ambiguous phrasing or poor textual interpretation by the dispute settlement bodies of the World Trade Organization. As a result, there exists a potential within the Agreement to have a significant detrimental impact on the international trading opportunities of exporting developing countries. In this thesis I analyse the provisions of the Agreement to determine where, why and how they are likely to have, or are having, a detrimental impact on developing countries (particularly exporting developing countries). After identifying these problems I examine and discuss several potential solutions and how they may be implemented to minimise - or even remove - the negative impact on developing countries and their international trading markets.
- Full Text:
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