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No Thumbnail AvailableProjectPreliminary studies on the effects of three animal manures on the ecological conditions of pond water and fish growth
Establishment of a Network of Aquaculture Centres in Asia
1983Also available in:
No results found.The use of organic manure in aquaculture is one of the main inputs in the Chinese system of integrated fish farming. Although many scientists in China and elsewhere have done much work on the effects of animal manure on aquaculture production (Chen Qiyu et al, 1982, Buck, 1978. 1979; Schroeder 1978, 1980; McGeacin et al, 1982; Stickney, 1977; Jhingran et al, 1980; Edwards, 1980; Zweig, 1981), little is known of the series of physical, chemical and biological processes which are taking place in a pond after application of manure. The complexity of energy recycling needs further studies. The aim of this study is to determine the independent contribution of three animal manures to changes in the ecological condition of pond water and fish production. The results to be obtained may provide the scientific basis for further research on the use of organic manure in fish culture. -
No Thumbnail AvailableProjectSite selection for aquaculture: biological productivity of water bodies
Establishment of African Regional Aquaculture Centre
1987Also available in:
No results found.Biological productivity as an index of water quality and production potential of cultured organism needs prime consideration for site selection. Productivity in terms of qualitative and quantitative aspects of plankton and benthos are treated separately, in this manual. In the present discussion we shall look first at primary production and then show this influences secondary production in water bodies. We shall explain first certain concepts to elucidate aspects of productivity and then the ene rgy flow in an ecosystem and the importance of this information in aquaculture. Finally we shall briefly refer to the methods of measuring productivity. We have had occasion to look at the various physical and chemical and certain biological characteristics of water bodies and their influence on fish production and aquaculture in particular. I specially refer to the exercise on correlating fish production and dissolved solids (conductivity) and depth of water bodies, using Rider's (Ryder et al ., 1974) morpho-edaphic index, MEI, (Handerson & Wellcome, 1974). It is quite obvious that there is a strong correlation between fish production and the amount of dissolved solids (inversely correlated with depth of the water body), in fresh waters except generally at the extreme high level. This has to be so because fish production is based on the productivity of water which is again, correlated directly with the amount of available nutrients and minerals, most often reflected by the dissolved solid content. Before we enter into a discussion on productivity, it would be helpful to look at the concepts of the ecosystem, habitat and ecological niche, and food cycle in water bodies, including food chain and trophic structure. These terms are of specific interest to aquaculture and productivity in general and therefore deserve some consideration. -
No Thumbnail AvailableProjectSocio-economic and marketing constraints to the development of aquaculture and utilisation of small water bodies in Zimbabwe 1989
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No results found.A questionnaire survey was administered in Murehwa and Masvingo Districts and 160 fish farming households (FFH) and 80 non-fish farming households (NFFH) were interviewed. Of those FFH interviewed, 25 were female-headed and 28 NFFH interviewed were female-headed. The study found that the potential for aquaculture development was relatively higher in wetter areas like NRs II and III, but because NRs IV and V are relatively dry and a large number of dams have been built there, they are, however, suited to the exploitation of these fisheries. Fish farming households were generally the wealthier households in the community. FFHs had more land and labour, produced more field and horticultural crops than NFFHs. Integration of fish farming within the farming systems was more likely among farmers with irrigated garden plots than those without; so that concentrating the extension message on this target audience could increase AGRITEX's impact. The majority of NFFH were aware of fish farmi ng in all NRs implying that the extension project had a significant impact in the pilot zones. Although they were aware of fish farming, they did not have suitable land for siting a pond and failed to hire enough labour to construct the pond. The proportion of female-headed FFH was relatively high in wetter areas (NR II) but lower in NRs III and IV. Although the average proportion of female-headed FFH was fairly standard, the absolute sample size was too low to permit rigorous examination of s ocio-economic differences among different gender groups. Wives in male-headed households were responsible for day-to-day pond management but the decisions of their husbands dominated. Fish farming was considered a sideline activity which required little management.
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