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  • 1
    Digitale Medien
    Digitale Medien
    Optimum food particle size in relation to body size of common carp, Cyprinus carpio L., fry (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Aquaculture research 23 (1992), S. 0 
    Details
    ISSN: 1365-2109
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract. An investigation was conducted under laboratory conditions to determine the optimum food particle size of an inert diet for common carp fry ranging in size from 15 to 466mg body weight and 13 to 31 mm total length (TL). Speed of consumption of a standard quantity of food was used as a measurement of feeding preference/efficiency for different particle size ranges. It was observed that for carp of this size range preferred food particle size increases with fish size. On the basis of ingestion time and feeding behaviour, food particle sizes in the ranges 125-300μm. 300-500μm, 300-790μm and 500-1000μm diameter were found to be most appropriate for carp fry weighing 15-23mg(TL 13-18), 46-97 mg(TL 17-22), 105-209 mg (TL 20-25) and 210-466mg (TL 24-31) respectively. This study also demonstrated that for carp fry of these size ranges the mean preferred food particle sizes are about 02-04 that of mouth size. Based on this relationship, general recommendations are made on the optimum food particle sizes for different size classes of carp fry reared under hatchery and nursery conditions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2109.1992.tb00774.x
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  • 2
    Digitale Medien
    Digitale Medien
    Improving spawning synchrony in the Nile tilapia, Oreochromis niloticus (L.) (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Aquaculture research 24 (1993), S. 0 
    Details
    ISSN: 1365-2109
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract. The development stage and number of seed (eggs and fry) removed from individual incubating Oreochromis niloticus (L.) broodfish at 10-day interharvest intervals (IHI) was compared with the harvest of free-swimming fry from undisturbed fish held in a tank within the same system. Spawning synchrony and productivity were compared for (1) total exchange of females for ‘conditioned’ females after each harvest, (2) exchange of only spawned females, and (3) return of females back into the spawning tank. Improved synchrony and seed production were positively related to removal of eggs and fry from incubating females and could have important implications for broodstock management in commercial hatcheries. Allowing fish to remain undisturbed in clear water tanks may lead to inhibition of spawning activity related to the formation of hierarchies. Individual weight loss by females during incubation was correlated with stage of seed harvested and thus with timing of spawning during the interharvest interval.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2109.1993.tb00563.x
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  • 3
    Digitale Medien
    Digitale Medien
    Broodstock management and the potential to improve the exploitation of mangrove crabs, Scylla serrata (Forskål), through pond fattening in Ranong, Thailand (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Aquaculture research 24 (1993), S. 0 
    Details
    ISSN: 1365-2109
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Mangrove crabs, Scylla serrata (Forskål), represent one of the main economic resources in the Ranong mangrove ecosystem on the Andaman Sea cost of southern Thailand. However, there is a serious problem of overfishing which has caused fishermen increasingly to sell undersized crabs to meet market demand and maintain their income levels. The crab population and fishing activities were studied to assess the scope for better management of the fishery, especially protection of female broodstock, and the feasibility of using young crabs for aquaculture. Berried crabs examined were always larger than 10·0cm (carapace width), with the great majority of females maturing in the size range 10·0–11·5cm. Gonosomatic index values peak in September, within a main egg carrying and spawning period from July to December. Protecting female crabs from fishing pressure during this season, plus limits on the harvesting of crabs less than 10cm, or using them for fattening in ponds, could lead to better utilization of this resource. Crab farming in Ranong is constrained by climatic factors, the presence of acid-sulphate soils and lack of technical knowledge among the local fishermen. An attempt initially to culture crabs from Ranong under more favourable conditions at Surat Thani showed limited success. Nonetheless, there is a considerable price differential between wild and pond-fattened crabs to encourage further interest in crab farming in Ranong.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2109.1993.tb00549.x
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  • 4
    Digitale Medien
    Digitale Medien
    Aquaculture and the environment: the supply of and demand for environmental goods and services by Asian aquaculture and the implications for sustainability (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Aquaculture research 28 (1997), S. 0 
    Details
    ISSN: 1365-2109
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: The present paper explores the relationships between aquaculture and the environment In Asia, focusing on the demands for environmental goods and services among different sectors. Aquaculture in the region accounts for 88% of global production by weight and 80% by value. Nevertheless, environmental problems are increasingly apparent and the higher the demands for environmental goods and services, the more negative the impacts. Against a background of rapid social, economic and political change, the paper considers how the sustainability of the industry is best assured. An integrated view of resource use, in which aquaculture is but one activity, is necessary for sustainable development. The roles of planning, education, research and environmental management schemes are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-2109.1997.00944.x
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  • 5
    Digitale Medien
    Digitale Medien
    Effect of chloride concentration on the acute toxicity of nitrite to common carp, Cyprinus carpio L., fry (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Aquaculture research 17 (1986), S. 0 
    Details
    ISSN: 1365-2109
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract. Duplicate static bioassays were conducted for 168 h each to determine the median lelhal concentration (LC50) of nitrite (NO−2) for common carp, Cyprinus carpio L., fry at five different chloride (Cl−) levels. The acute toxicity of nilrite ceased towards the end of 96 h at all levels of chloride concentration. There was a highly significant positive correlation between the chloride concentration tested and the 96-h LC50. The 96-h LC50 values are 2·55, 5·77, 14·41 27·26 and 48·70 mgl−1 NO−2-N at chloride concentration of 1·0. 5·0, 10·5, 27·3 and 45·0 mgl−1 Cl− respectively. The linear relationship between chloride concentration and 96-h LC50 is best described by the equation: y= 1·03x+ 1·49 (r=+ 0·996; d.f. = 3;P 〈0·001), where y= 96 h LC50 of NO−2-N and x= concentration of Cl−. A NO−2-N to Cl− ratio of about 1:1·5–3·0 prevented complete mortality over the 168-h experimental period. A NO−2-N to Cl− ratio of 1:5 is recommended for protection of carp fry against nilrite mortality in fish farms.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2109.1986.tb00082.x
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  • 6
    Digitale Medien
    Digitale Medien
    Hormonal sex reversal of wild-spawned tilapia in India (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 26 (1985), S. 0 
    Details
    ISSN: 1095-8649
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: The effectiveness of methyltestosterone (MT) for sex reversal and growth promotion in Oreochromis mossambicus was studied in culture experiments in India. Wild-spawned fry were treated with 30 μg MT g−1 diet for 30 or 60 days at two feeding levels (initially 20% or 10% of body weight daily). The fish were grown on for 66–96 days after the hormone treatment period in fertilized cement ponds without supplementary feeding. Tilapia treated with MT for 60 days attained an average weight of 29.0 g compared to 18.8 g for untreated fish reared under similar conditions. The percentage of males among the untreated tilapia was 58%, MT treatment for 30 days significantly increased this percentage at the higher feeding level (79% male), but not at the lower feeding level (51%). More than 90% of the tilapia in both 60 day MT treatment groups were male; 3% of all the fish reared showed an intersex condition. The experiments demonstrated that the anabolic and sex reversal effects of MT on tilapia are proportional to the duration of treatment and quantity of hormone administered. The possible application of monosex tilapia culture in tropical countries is noted.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1095-8649.1985.tb04245.x
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  • 7
    Digitale Medien
    Digitale Medien
    Multivariate analysis of the mud crab Scylla serrata (Brachyura: Portunidae) from four locations in Southeast Asia (1997)
    Springer
    Marine biology 128 (1997), S. 55-62 
    Details
    ISSN: 1432-1793
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The large, edible mud crab Scylla serrata (Forskål) exhibits different phenotypes which are recognised by the fishermen of Southeast Asia and are given local names such as “white”, “green”, “red” or “black” crabs on the basis of their colouration. A preliminary study using multivariate techniques was undertaken in order to examine the degree of dissimilarity between the different morphs of commercially fished stocks of S. serrata. Twenty-two morphometric and 20 meristic characters were measured on male crabs from four locations in three countries in Southeast Asia, including Surat Thani in Thailand where “black” and “white” morphs exist sympatrically. Canonical variate analysis (CVA) on the morphometric data discriminated three groups with no chain-linking. Surat Thani “white” crabs and those from south Vietnam were phenotypically similar and formed one distinct group; a second group contained crabs from Ranong (Thailand) and Sarawak which were phenotypically “black”; the third group contained “black” crabs from Surat Thani. CVA on meristic data confirmed two groupings, but implied that the Surat Thani “black” morph may only be a variant of the Surat Thani/Vietnam “white” form, rather than a third species. These findings are discussed in relation to the ecology, fishery management and aquaculture potenial of S. serrata.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002270050068
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