Aquaculture as we know it at the beginning of the 21st century is a consolidation of more or less... more Aquaculture as we know it at the beginning of the 21st century is a consolidation of more or less independent experiences. Carvings indicate that the Egyptians were cultivating fish at least 2,500 years ago. The Chinese claim to have been growing fish for centuries. The Romans had fishponds (piscinae). In the 14th century, the emperor Charles IV ordered all towns to build fish ponds to produce food, enhance the local environment and protect watersheds. Paleolithic Hawaiian Islanders isolated embayments for rearing fish in the sea. Whatever the original objective of these aquaculture initiatives was, from each evolved a set of concepts that, until quite recently, strongly influenced how aquaculture interacted with local society and the environment. One could argue that modern, global aquaculture arose from these different local traditions only in the second half of the 20th century. Scientific evaluation of the integrated agriculture-aquaculture systems that had evolved in China bega...
Two commercial caged fish farms, located in the Asuogyaman district of the Eastern Region of Ghan... more Two commercial caged fish farms, located in the Asuogyaman district of the Eastern Region of Ghana, were assessed for their social and economic impacts on rural communities around their locations. Three groups of people; farm managers, farm workers and farmed fish traders were interviewed by the authors using semi-structured questionnaires to obtain data. Identified benefits to the local communities included increased employment opportunities, improved nutrition and health through enhanced availability of fish and improved infrastructure through, for example, construction of vehicular access roads to communities that would not have occurred but for the existence of the fish farm. Benefits to workers of fish farms and their families were in the form of regular incomes, bonuses, possibility of loans and contribution to social security funds by employers (Farms), which also entitled the workers to an old age pension, invalidity pension, survivors' lump sum payment to families of th...
The current, highly centralized approach to fisheries management seems to be incapable of coping ... more The current, highly centralized approach to fisheries management seems to be incapable of coping with escalating resource depletion and environmental degradation. Co-management has been identified as an alternative. This paper compares various approaches to fisheries management and discusses their performance in relation to the nature of the fishery. It is concluded that in African fisheries, stringent institutional arrangements, poor human, technical and financial resources, and a limited time frame often thwart co-management approaches. However, with the right conditions and prerequisites, comanagement can be successful in improving compliance with regulations and maintaining or enhancing the quality of the resource. The paper brings out the issues that require further research.
ABSTRACT Freshwaters contribute 15 percent of the world’s reported fish catch, or about 10.1 mill... more ABSTRACT Freshwaters contribute 15 percent of the world’s reported fish catch, or about 10.1 million tonnes in 2006, most of which comes from tropical systems. The true contribution of tropical inland fisheries is likely to be higher, as less than half of the inland capture production is actually reported. While reservoir fisheries are already an essential component of this production, the potential of most of them may even exceed their current catch levels. Opportunities exist to increase productivity, provided that environmentally and socially sustainable management systems can be adopted. To realize this untapped potential, it is necessary to improve understanding of the processes influencing reservoir productivity in such a way as to involve both biological principles and stakeholder participation, as each reservoir has different properties and different research and management institutions. Seen in isolation, catch and productivity data of individual reservoirs may be difficult to interpret. The present technical paper attempts to address this issue by reviewing the knowledge accumulated in reservoirs in some very different tropical river basins: the Indus and Ganges/Brahmaputra Basin in India, the Nile River Basin in Eastern Africa and the Volta River Basin in West Africa. In particular, it focuses on many of the reservoirs of northern India and Pakistan in the Indus and Ganges systems, Lake Nasser in the Nile River and Lake Volta in the Volta River. Information collated from grey and published literature on the three basins is synthesized and standardized with reference to wider knowledge and up-to-date information on tropical reservoir fisheries. A considerable quantity of data and information were collected on many aspects of the systems of the three reservoirs, including hydrological, biophysical and limnological features, primary production, and fish and fisheries data. This information was condensed and synthesized with the aim of providing a baseline against which the ecological changes that have taken place since impoundment can be described and analysed. Efforts are made to explain changes in fish catch in relation to climatic variations, ecological succession and fishing effort. The review shows that biological data and information are generally available. However, as is also common elsewhere, all three cases suffer from the general tendency to isolate and compartmentalize research into separate disciplines. Usually, there is very limited cross-disciplinary flow of information or recognition of how results of various disciplines can contribute to a more comprehensive understanding of the behaviour of fish populations, human communities and ecosystems and the productive activities that depend on them. This uniform tendency severely hampered the identification of relevant management actions. A more pragmatic and holistic understanding of reservoir ecosystems is needed in order to guide the choice of indicators and the development of monitoring systems that can inform management of changes in reservoir productivity and, hence, the potential catch. The next step would be to devise a hierarchy of indicators describing the different ecological and economic processes influencing fisheries catches and to organize monitoring systems around those indicators. Only by combining information across sectoral disciplines will it be possible to reach a better understanding of the processes that drive fish stocks, fisheries and reservoir productivity.
ABSTRACT Freshwaters contribute 15 percent of the world’s reported fish catch, or about 10.1 mill... more ABSTRACT Freshwaters contribute 15 percent of the world’s reported fish catch, or about 10.1 million tonnes in 2006, most of which comes from tropical systems. The true contribution of tropical inland fisheries is likely to be higher, as less than half of the inland capture production is actually reported. While reservoir fisheries are already an essential component of this production, the potential of most of them may even exceed their current catch levels. Opportunities exist to increase productivity, provided that environmentally and socially sustainable management systems can be adopted. To realize this untapped potential, it is necessary to improve understanding of the processes influencing reservoir productivity in such a way as to involve both biological principles and stakeholder participation, as each reservoir has different properties and different research and management institutions. Seen in isolation, catch and productivity data of individual reservoirs may be difficult to interpret. The present technical paper attempts to address this issue by reviewing the knowledge accumulated in reservoirs in some very different tropical river basins: the Indus and Ganges/Brahmaputra Basin in India, the Nile River Basin in Eastern Africa and the Volta River Basin in West Africa. In particular, it focuses on many of the reservoirs of northern India and Pakistan in the Indus and Ganges systems, Lake Nasser in the Nile River and Lake Volta in the Volta River. Information collated from grey and published literature on the three basins is synthesized and standardized with reference to wider knowledge and up-to-date information on tropical reservoir fisheries. A considerable quantity of data and information were collected on many aspects of the systems of the three reservoirs, including hydrological, biophysical and limnological features, primary production, and fish and fisheries data. This information was condensed and synthesized with the aim of providing a baseline against which the ecological changes that have taken place since impoundment can be described and analysed. Efforts are made to explain changes in fish catch in relation to climatic variations, ecological succession and fishing effort. The review shows that biological data and information are generally available. However, as is also common elsewhere, all three cases suffer from the general tendency to isolate and compartmentalize research into separate disciplines. Usually, there is very limited cross-disciplinary flow of information or recognition of how results of various disciplines can contribute to a more comprehensive understanding of the behaviour of fish populations, human communities and ecosystems and the productive activities that depend on them. This uniform tendency severely hampered the identification of relevant management actions. A more pragmatic and holistic understanding of reservoir ecosystems is needed in order to guide the choice of indicators and the development of monitoring systems that can inform management of changes in reservoir productivity and, hence, the potential catch. The next step would be to devise a hierarchy of indicators describing the different ecological and economic processes influencing fisheries catches and to organize monitoring systems around those indicators. Only by combining information across sectoral disciplines will it be possible to reach a better understanding of the processes that drive fish stocks, fisheries and reservoir productivity.
Concentrations of faecal bacteria and heavy metals (Cr, Cd, Hg, Pb and Zn) were measured in fish,... more Concentrations of faecal bacteria and heavy metals (Cr, Cd, Hg, Pb and Zn) were measured in fish, mud and water from two urban lakes in Yaoundé, Cameroon. The mean densities of faecal coliforms (FC) and faecal streptococ ci (FS) in water were 6 160 ± 8 493CFU 100ml and 387 ± 320CFU 100ml, respectively, in Lac Central, and 8 376
Aquaculture as we know it at the beginning of the 21st century is a consolidation of more or less... more Aquaculture as we know it at the beginning of the 21st century is a consolidation of more or less independent experiences. Carvings indicate that the Egyptians were cultivating fish at least 2,500 years ago. The Chinese claim to have been growing fish for centuries. The Romans had fishponds (piscinae). In the 14th century, the emperor Charles IV ordered all towns to build fish ponds to produce food, enhance the local environment and protect watersheds. Paleolithic Hawaiian Islanders isolated embayments for rearing fish in the sea. Whatever the original objective of these aquaculture initiatives was, from each evolved a set of concepts that, until quite recently, strongly influenced how aquaculture interacted with local society and the environment. One could argue that modern, global aquaculture arose from these different local traditions only in the second half of the 20th century. Scientific evaluation of the integrated agriculture-aquaculture systems that had evolved in China bega...
Two commercial caged fish farms, located in the Asuogyaman district of the Eastern Region of Ghan... more Two commercial caged fish farms, located in the Asuogyaman district of the Eastern Region of Ghana, were assessed for their social and economic impacts on rural communities around their locations. Three groups of people; farm managers, farm workers and farmed fish traders were interviewed by the authors using semi-structured questionnaires to obtain data. Identified benefits to the local communities included increased employment opportunities, improved nutrition and health through enhanced availability of fish and improved infrastructure through, for example, construction of vehicular access roads to communities that would not have occurred but for the existence of the fish farm. Benefits to workers of fish farms and their families were in the form of regular incomes, bonuses, possibility of loans and contribution to social security funds by employers (Farms), which also entitled the workers to an old age pension, invalidity pension, survivors' lump sum payment to families of th...
The current, highly centralized approach to fisheries management seems to be incapable of coping ... more The current, highly centralized approach to fisheries management seems to be incapable of coping with escalating resource depletion and environmental degradation. Co-management has been identified as an alternative. This paper compares various approaches to fisheries management and discusses their performance in relation to the nature of the fishery. It is concluded that in African fisheries, stringent institutional arrangements, poor human, technical and financial resources, and a limited time frame often thwart co-management approaches. However, with the right conditions and prerequisites, comanagement can be successful in improving compliance with regulations and maintaining or enhancing the quality of the resource. The paper brings out the issues that require further research.
ABSTRACT Freshwaters contribute 15 percent of the world’s reported fish catch, or about 10.1 mill... more ABSTRACT Freshwaters contribute 15 percent of the world’s reported fish catch, or about 10.1 million tonnes in 2006, most of which comes from tropical systems. The true contribution of tropical inland fisheries is likely to be higher, as less than half of the inland capture production is actually reported. While reservoir fisheries are already an essential component of this production, the potential of most of them may even exceed their current catch levels. Opportunities exist to increase productivity, provided that environmentally and socially sustainable management systems can be adopted. To realize this untapped potential, it is necessary to improve understanding of the processes influencing reservoir productivity in such a way as to involve both biological principles and stakeholder participation, as each reservoir has different properties and different research and management institutions. Seen in isolation, catch and productivity data of individual reservoirs may be difficult to interpret. The present technical paper attempts to address this issue by reviewing the knowledge accumulated in reservoirs in some very different tropical river basins: the Indus and Ganges/Brahmaputra Basin in India, the Nile River Basin in Eastern Africa and the Volta River Basin in West Africa. In particular, it focuses on many of the reservoirs of northern India and Pakistan in the Indus and Ganges systems, Lake Nasser in the Nile River and Lake Volta in the Volta River. Information collated from grey and published literature on the three basins is synthesized and standardized with reference to wider knowledge and up-to-date information on tropical reservoir fisheries. A considerable quantity of data and information were collected on many aspects of the systems of the three reservoirs, including hydrological, biophysical and limnological features, primary production, and fish and fisheries data. This information was condensed and synthesized with the aim of providing a baseline against which the ecological changes that have taken place since impoundment can be described and analysed. Efforts are made to explain changes in fish catch in relation to climatic variations, ecological succession and fishing effort. The review shows that biological data and information are generally available. However, as is also common elsewhere, all three cases suffer from the general tendency to isolate and compartmentalize research into separate disciplines. Usually, there is very limited cross-disciplinary flow of information or recognition of how results of various disciplines can contribute to a more comprehensive understanding of the behaviour of fish populations, human communities and ecosystems and the productive activities that depend on them. This uniform tendency severely hampered the identification of relevant management actions. A more pragmatic and holistic understanding of reservoir ecosystems is needed in order to guide the choice of indicators and the development of monitoring systems that can inform management of changes in reservoir productivity and, hence, the potential catch. The next step would be to devise a hierarchy of indicators describing the different ecological and economic processes influencing fisheries catches and to organize monitoring systems around those indicators. Only by combining information across sectoral disciplines will it be possible to reach a better understanding of the processes that drive fish stocks, fisheries and reservoir productivity.
ABSTRACT Freshwaters contribute 15 percent of the world’s reported fish catch, or about 10.1 mill... more ABSTRACT Freshwaters contribute 15 percent of the world’s reported fish catch, or about 10.1 million tonnes in 2006, most of which comes from tropical systems. The true contribution of tropical inland fisheries is likely to be higher, as less than half of the inland capture production is actually reported. While reservoir fisheries are already an essential component of this production, the potential of most of them may even exceed their current catch levels. Opportunities exist to increase productivity, provided that environmentally and socially sustainable management systems can be adopted. To realize this untapped potential, it is necessary to improve understanding of the processes influencing reservoir productivity in such a way as to involve both biological principles and stakeholder participation, as each reservoir has different properties and different research and management institutions. Seen in isolation, catch and productivity data of individual reservoirs may be difficult to interpret. The present technical paper attempts to address this issue by reviewing the knowledge accumulated in reservoirs in some very different tropical river basins: the Indus and Ganges/Brahmaputra Basin in India, the Nile River Basin in Eastern Africa and the Volta River Basin in West Africa. In particular, it focuses on many of the reservoirs of northern India and Pakistan in the Indus and Ganges systems, Lake Nasser in the Nile River and Lake Volta in the Volta River. Information collated from grey and published literature on the three basins is synthesized and standardized with reference to wider knowledge and up-to-date information on tropical reservoir fisheries. A considerable quantity of data and information were collected on many aspects of the systems of the three reservoirs, including hydrological, biophysical and limnological features, primary production, and fish and fisheries data. This information was condensed and synthesized with the aim of providing a baseline against which the ecological changes that have taken place since impoundment can be described and analysed. Efforts are made to explain changes in fish catch in relation to climatic variations, ecological succession and fishing effort. The review shows that biological data and information are generally available. However, as is also common elsewhere, all three cases suffer from the general tendency to isolate and compartmentalize research into separate disciplines. Usually, there is very limited cross-disciplinary flow of information or recognition of how results of various disciplines can contribute to a more comprehensive understanding of the behaviour of fish populations, human communities and ecosystems and the productive activities that depend on them. This uniform tendency severely hampered the identification of relevant management actions. A more pragmatic and holistic understanding of reservoir ecosystems is needed in order to guide the choice of indicators and the development of monitoring systems that can inform management of changes in reservoir productivity and, hence, the potential catch. The next step would be to devise a hierarchy of indicators describing the different ecological and economic processes influencing fisheries catches and to organize monitoring systems around those indicators. Only by combining information across sectoral disciplines will it be possible to reach a better understanding of the processes that drive fish stocks, fisheries and reservoir productivity.
Concentrations of faecal bacteria and heavy metals (Cr, Cd, Hg, Pb and Zn) were measured in fish,... more Concentrations of faecal bacteria and heavy metals (Cr, Cd, Hg, Pb and Zn) were measured in fish, mud and water from two urban lakes in Yaoundé, Cameroon. The mean densities of faecal coliforms (FC) and faecal streptococ ci (FS) in water were 6 160 ± 8 493CFU 100ml and 387 ± 320CFU 100ml, respectively, in Lac Central, and 8 376
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