Robin Welcomme - Academia.edu (original) (raw)
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Papers by Robin Welcomme
The designations employed and the presentation of material in this information product do not imp... more The designations employed and the presentation of material in this information product do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations concerning the legal or development status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.
Nature, 1962
No. 4823 April 7, 1962 NATURE 107 ray. All five species, which lack retia, exhibit very low oxyge... more No. 4823 April 7, 1962 NATURE 107 ray. All five species, which lack retia, exhibit very low oxygen tensions at the retina, less than 30 mm. mercury. The observed correlation between the measured oxygen tension and the extent to which the choroid rete mirabile is developed suggests that the rete plays an essential part in establishing the large oxygen tension at the retina. Two instances of transport of oxygen gas against a large concentration difference are now known. In each instance a rete mirabile is presumed to be the seat of transport, the gas gland or pigment epithelium playing an unknown but subsidiary part. The interesting question to be resolved is whether oxygen transport is a general property of cells magnified to easily measurable proportions by the rete mirabile acting as a counter-current multiplier 16 , or is some special property of the rete-gland complex. One of us (J. B. W.
The aquatic ecosystem work of the Challenge Program (CP) on Water and Food will seek to develop a... more The aquatic ecosystem work of the Challenge Program (CP) on Water and Food will seek to develop and apply systems of management that sustain and, where possible, enhance the benefits to people from these systems as an integral part of approaches to improving water productivity at the basin level. It will do so through analysis, development and dissemination of tools and methodologies that will foster effective governance of aquatic ecosystems and their resources. This will be done through development, application and dissemination of tools that will provide quality information on the value and water requirements of these ecosystems and ways to enhance their productivity, and by strengthening the capacity to use these tools and techniques. To help ensure that this process begins by focusing on clear priorities, the present paper examines issues of governance, valuation, productivity and flow requirements and sets out the research questions that require immediate attention.
In Molden, David (Ed.). Water for food, water for life: a Comprehensive Assessment of Water Manag... more In Molden, David (Ed.). Water for food, water for life: a Comprehensive Assessment of Water Management in Agriculture. London, UK: Earthscan; Colombo, Sri Lanka: International Water Management Institute (IWMI)
Lake Victoria is Africa's single most important source of inland fishery production. After it was... more Lake Victoria is Africa's single most important source of inland fishery production. After it was initially fished down in the first half of the 20th century, Lake Victoria became home to a series of introduced food fishes, culminating in the eventual demographic dominance of the Nile perch, Lates niloticus. Simultaneously with the changes in fish stocks, Lake Victoria experienced dramatic changes in its ecology. The lakefishery during most of the 20th century was a multispecies fishery resting on a diverse lake ecosystem, in which native food fishes were targeted. The lake ended the century with a much more productive fishery, but one in which three species-two of them introduced-made up the majority of the catch. Although many fish stocks in Lake Victoria had declined before the expansion of the Nile perch population, a dramatic increase in the population size of Nile perch in the 1980s roughly coincided with the drastic decline or disappearance of many indigenous species. Now, two decades after the rise of Nile perch in Lake Victoria, this species has shown signs of being overfished, and some of the native species that were in retreat-or even thought extinct-are now reemerging. Data on the resurgence of the indigenous species suggest that heavy fishing of Nile perch may enhance biodiversity; this has spawned renewed interest in management options that promote both fishery sustainability and biodiversity conservation.
Fisheries Management, 2000
The designations employed and the presentation of material in this information product do not imp... more The designations employed and the presentation of material in this information product do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations concerning the legal or development status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.
Nature, 1962
No. 4823 April 7, 1962 NATURE 107 ray. All five species, which lack retia, exhibit very low oxyge... more No. 4823 April 7, 1962 NATURE 107 ray. All five species, which lack retia, exhibit very low oxygen tensions at the retina, less than 30 mm. mercury. The observed correlation between the measured oxygen tension and the extent to which the choroid rete mirabile is developed suggests that the rete plays an essential part in establishing the large oxygen tension at the retina. Two instances of transport of oxygen gas against a large concentration difference are now known. In each instance a rete mirabile is presumed to be the seat of transport, the gas gland or pigment epithelium playing an unknown but subsidiary part. The interesting question to be resolved is whether oxygen transport is a general property of cells magnified to easily measurable proportions by the rete mirabile acting as a counter-current multiplier 16 , or is some special property of the rete-gland complex. One of us (J. B. W.
The aquatic ecosystem work of the Challenge Program (CP) on Water and Food will seek to develop a... more The aquatic ecosystem work of the Challenge Program (CP) on Water and Food will seek to develop and apply systems of management that sustain and, where possible, enhance the benefits to people from these systems as an integral part of approaches to improving water productivity at the basin level. It will do so through analysis, development and dissemination of tools and methodologies that will foster effective governance of aquatic ecosystems and their resources. This will be done through development, application and dissemination of tools that will provide quality information on the value and water requirements of these ecosystems and ways to enhance their productivity, and by strengthening the capacity to use these tools and techniques. To help ensure that this process begins by focusing on clear priorities, the present paper examines issues of governance, valuation, productivity and flow requirements and sets out the research questions that require immediate attention.
In Molden, David (Ed.). Water for food, water for life: a Comprehensive Assessment of Water Manag... more In Molden, David (Ed.). Water for food, water for life: a Comprehensive Assessment of Water Management in Agriculture. London, UK: Earthscan; Colombo, Sri Lanka: International Water Management Institute (IWMI)
Lake Victoria is Africa's single most important source of inland fishery production. After it was... more Lake Victoria is Africa's single most important source of inland fishery production. After it was initially fished down in the first half of the 20th century, Lake Victoria became home to a series of introduced food fishes, culminating in the eventual demographic dominance of the Nile perch, Lates niloticus. Simultaneously with the changes in fish stocks, Lake Victoria experienced dramatic changes in its ecology. The lakefishery during most of the 20th century was a multispecies fishery resting on a diverse lake ecosystem, in which native food fishes were targeted. The lake ended the century with a much more productive fishery, but one in which three species-two of them introduced-made up the majority of the catch. Although many fish stocks in Lake Victoria had declined before the expansion of the Nile perch population, a dramatic increase in the population size of Nile perch in the 1980s roughly coincided with the drastic decline or disappearance of many indigenous species. Now, two decades after the rise of Nile perch in Lake Victoria, this species has shown signs of being overfished, and some of the native species that were in retreat-or even thought extinct-are now reemerging. Data on the resurgence of the indigenous species suggest that heavy fishing of Nile perch may enhance biodiversity; this has spawned renewed interest in management options that promote both fishery sustainability and biodiversity conservation.
Fisheries Management, 2000