Shifting rice farming to fish culture in some selected areas of Mymensingh, Bangladesh: the process, conflicts and impacts

The evolutionary process of converting low-lying paddy fields into fish farms and its impact on agrarian communities in some selected areas of Mymensingh district were studied. This study was conducted through participatory rural appraisal (PRA) covering 12 villages from each of selected upazillas viz. Fulpur and Haluaghat of Mymensing [sic] district. A total of 12 PRA sessions were conducted where 90 farmers participated during 29 July to 26 August 2004. It is seen that the use of low-lying paddy fields was mostly confined to Broadcast Aman (B. Aman) rice production until 1960s. With the introduction of modern rice farming technology, the farmers started to produce Boro rice in Rabi season and B. Aman rice in Kharif season. With the passage of time, aquaculture technologies have been evolved and the farmers realized that fish farming is more profitable than rice cultivation, and then they started to utilize their paddy fields for alternate rice-fish farming and rice-cum-fish farming. Now a days, aquaculture based crop production system is in practice in more than 25% of the low-lying paddy fields. Conversion of rice fields in to fish ponds has brought up a change in the livelihood patterns of the rural farmers. The areas where the farmers involved themselves in the new production systems were fingerling collection, transportation and marketing of fry and fingerlings. During 1960s to 1970s, a few people used to culture fish in the permanent ponds for their own consumption, the species produced were rohu, catla, mrigal, ghainna, long whiskered catfish, freshwater shark (boal), snake head (shol) etc. Small fishes like climbing perch, stinging catfish, walking catfish, barb, minnows etc. were available in the rice fields during monsoon season. In 1980s to mid 1990s, some rice fields were converted into fish ponds and the people started to produce fish for commercial purposes. When rice-fish farming became profitable, a large number of people started converting their rice fields in to rice-fish culture ponds. Culture of some exotic fishes like silver carp, tilapia, grass carp, silver barb etc. also started in the paddy fields. Higher income from fish farming contributed positively in improving the housing, sanitation and education system in the study areas. It is seen that the medium and medium high lands were only used for alternate rice fish farming. The net income was high in any fish based cropping system that motivated the farmers to introduce fish based cropping system in the low-lying inland areas. As a result, the regional as well as communal income disparities occurred. However, the extraction of ground water became common during the dry period as the water was used for both rice and fish farming. Mass conversion of paddy fields into rice-fish culture ponds caused water logging in the study areas. In most cases, the participated farmers mentioned that they could be easily benefited by producing fish with T. Aman or only fish during the monsoon season. They agreed that this was an impressive technology to them and they could generate employment opportunities throughout the year. Finally, the social, economic and technical problems which are acting as constraints to rapid expansion of fish production system were reported from the interviewee.

Guide to the meso-scale production of the copepod Acartia tonsa

This manual is intended as a guide for the daily production of a few million A. tonsa nauplii for feeding to marine vertebrates and invertebrates. This scale of production is greater than most research would require, but smaller than commercial production, hence the term meso-scale production. This manual will briefly describe the biology of Acartia tonsa Dana that is relevant to culture, the culture methodology for meso-scale production of their eggs and nauplii, the system components utilized in production, and how to construct a few simple tools useful for this scale of production. Commercial production of copepods requires much greater feed production than is described, or the development of an efficient artificial feed, and, therefore, is not the focus of this manual. (PDF conatains 29 pages.)

Culture of tropical sea cucumbers for stock restoration and enhancement

Severe overfishing of sea cucumbers has occurred in most countries of the tropical Indo-Pacific. The release of juveniles is being examined at the ICLARM Coastal Aquaculture Centre in the Solomon islands as a means of restoring and enhancing tropical sea cucumber stocks. Sandfish (Holothuria scabra) are the tropical species that show the best potential for stock enhancement. Sandfish are of high value, widely distributed and relatively easy to culture in simple systemss at a low cost. This paper summarizes information about the culture of H. scabra and compares it to that of the temperate species Stichopus japonicus.

Culture of Moina micrura on various organic waste products

Moina micrura, a cladoceran species, is considered to be one of the best live food organisms for rearing the young larval stages of fish and prawn. Considering the importance of this species in hatchery operations the present study was undertaken to record its fecundity and life span and to culture it using different locally available organic waste products. In indoor culture, a maximum production of 2600 ind/1 and a minimum of 1050 ind/1 were obtained when treated with gram + maize oilcake and "till" oilcake respectively. In outdoor culture, a highest production of 6000 ind/1 was achieved with "Alsi" and "till" oilcakes and a lowest density of 1050 ind/1 with coconut oilcake and raw cattle dung was obtained with an inoculation rate of 5 ind/1.

Culture feasibility of silver barb (Barbodes gonionotus Bleeker) and GIFT with shrimp (Penaeus monodon Feb.) in brackishwater pond

An experiment was conducted to understand the culture feasibility of sliver barb (Barbodes gonionotus) and GIFT (Genetically Improved Farmed Tilapia) with shrimp (Penaeus monodon). There were three different treatment (T) combinations: (T1) shrimp (10,000/ha) and silver barb (10,000/ha), (T2) shrimp (10,000/ha) and GIFT (10,000/ha), and (T3) shrimp (10,000/ha). Shrimp, after 120 days of culture, attained an average weight of 23.77g in T1, followed by T3 (23.70g). The highest average weight was recorded in T2 (24.93g). The specific growth rate (SGR) of shrimp was 6.9%, 6.94% and 6.9% for T1 T2 and T3, respectively. The SGR for the B. gonionotus and GIFT was 2.56% and 4.26%, respectively. The final weight of silver barb was 69.75g and that of GIFT was 161.83g. Survival of shrimp was higher (65.50%) in T2, followed by T3 (59.97%) and T1 (57.03%). Survival rate of silver barb (58.10%) was lower compared to that of GIFT (78.43%). Sporadic and scanty mortality of silver barb with a symptom of blind-red-protruded eye, swollen belly and body lesion was observed. Production of shrimp was higher of 284.05 kg/ha in monoculture, followed 162.47 kg/ha in concurrent culture with silver barb and 136.77 kg/ha culture with GIFT. In spite of similar stocking density of B. gonionotus and GIFT in T1 and T2, respectively, the production of GIFT was higher (1272.95 kg/ha) than that of silver barb ( 402.72kg/ha). Survival, final weight and production rates of shrimp among the treatments were found insignificant while total production of shrimp/fish was found to vary significantly (Pculture of B. gonionotus and shrimp will be less prospective in comparison to culture of GIFT and shrimp in brackish water environment with a salinity range of 9 to 14%o.

Culture experiments on the copepod, Tisbintra elongata MORI, and evaluation of that species as food organism for milkfish larvae

Five types of food were used to culture T. elongata: rice bran, cow dung, bread, cow dung, bread yeast, fermented fish solubles and Spirulina. Bread yeast was found to give the highest densities. An evaluation was also made of the effectivity of rice bran and fermented fish solubles for the outdoor mass culture of T. elongata . A comparative study on the growth and survival rate of milkfish fry (Chanos chanos) fed with T. elongata and Artemia showed there to be no significant differences between the diets.

Culture systems categorized: The fundamentals

The article presents the three basic categories of culture systems: open, semiclosed and closed systems. Open system culture generally refers to fish farming in natural bodies of water such as oceans, bays, estuaries, coastal lagoons, lakes or rivers. Semiclosed systems are those in which the culture water makes one pass through the system and is discharged. These are referred to as flow-through or once-through systems. The raceway falls into this category. Closed systems are those where the water is recondtioned and recirculated to culture units. These are also called the closed recirculating systems.

Influence of Sediment Nutrients on Growth of Emergent Hygrophila

Hygrophila ( Hygrophila polysperma (Roxb.) T. Anderson) is a plants which forms serious aquatic weed problems. Both submerged and emergent growth forms occur. Nutritional studies with a controlled release fertilizer and sediments collected from hygrophila-infested areas were conducted with the emergent growth habit to provide insights into growth of this introduced plant. Plant dry weights for experimental 16- week culture periods with low average temperatures were associated with low amounts of hygrophila biomass as compared to culture periods with high average temperatures. Hygrophila cultured in sand rooting media with the controlled release fertilizer produced as much as 20 times more dry weight than plants cultured in sediments only. First-degree linear regression statistics showed hygrophila dry weights were highly related to ammonia nitrogen, magnesium, sodium, and pH values in the sediments. These findings show the close relationship of the emergent growth habit of hygrophila to sediment nutrients. Analyses for certain sediment characteristics may provide an indication of the potential growth that may be expected for weed infestations of this plant. Hygrophila grows year round in south Florida; however, visual observations of canals and other bodies of water indicate that lower amounts of hygrophila plants occur during the cooler months of year than during the summer season. These findings show the seasonal growth of emergent hygrophila occurs with biomass dependent on both sediment nutrients and temperature.

The potentials for commercial production of fish feeds in Nigeria

Studies in fish feed technology revealed that there is a potential for big time investment into fish feed production and marketing in view of the growing awareness of fish farming in Nigeria. Intensification of aquaculture is one of the primary methods of food (finfish) production which requires technical knowledge and expertise in the formulation and manufacture of adequate feeds for the cultured species. Studies also revealed that all sort of food items were used by fish farmers ranging from animal dung, groundnut cake etc, to culture fish to table size because of non-availability of rightly prepared feeds. Inadequate knowledge of detailed requirements of tropical cultured species was found to pose a hindrance to formulation despite the fact that a lot has been accumulated in terms of biochemical and nutritive values of food sources in Nigeria. The investigation further revealed the challenges posed to researchers in aquaculture, fish nutritionists and fisheries biologists among others to elucidate the complete requirements of local fish species in terms of their protein, lipid and carbohydrate requirements such that their patents could be made available to companies like PFIZER, IBRU etc, and individuals alike to make commercialization of fish feeds a reality

The Status of Queen Conch, Strombus gigas, Research in the Caribbean

Today there are approximately 230 published scientific papers on queen conch, Strombus gigas. Publication on this species began in the 1960's and increased rapidly during the 1980's and 1990's (Fig. 1). The increase in publication after 1980 was associated with three particular areas ofendeavor. First, many articles were published to document the rapid depletion of conch stocks throughout the Caribbean Sea. Second, substantial progress was made in understanding processes related to growth, mortality, and reproduction in queen conch. Third, because of the apparent and widespread decline in conch, several research laboratories, especially in Florida, Puerto Rico, Venezuela, and the Turks and Caicos Islands began experiments related to hatchery production of juvenile conch. The primary intent was to replenish wild stocks by releasing hatchery-reared animals. Today, hatchery production has been relatively well perfected, and the increase in numbers of scientific papers related specifically to culture has slowed. A thorough review of the history of conch mariculture was provided by Creswell (1994), and Davis (1994) summarized the details of larval culture technique.

Monoculture of marine planktonic diatoms and the effects of different media on their growth and survival

Diatoms are the preferred live food of the protozoea stages of prawns. Due to seasonal variations, it is difficult to obtain continuous supply of diatoms and other algae throughout the year. Therefore mass culture of diatoms is necessary. At attempt was made to culture planktonic diatoms and to study the effect of Allen and Nelson media, Simon media, Vitamin B12 and treated sewage water media on their growth and survival. Navicula sp showed better growth in Allen and Nelson media, Coscinodiscus and Chaetoceros grew better in Simon media while Navicula sp and Coscinodiscus sp showed better growth in the combination of Allen and Nelson + Vitamin B12.

Toxigenic molds on fish feeds-1: impact of climatic change

The present communication is a survey report carried out to assess the incidence of toxic mycoflora on seven types of agriculture products/by products incorporated during fish culture as supplementary dietary items. Samples were obtained from various sources at Darbhanga, Madhubani and Samashtipur districts during summer, winter and monsoon months. Out of the total 1774 samples, only 894 appeared to be fresh visually reflecting average incidence of contamination around 46.6%. However, the apparently fresh samples, when subjected to culture, 26.9% of them were found to be contaminated. Thus, degree of fungal spoilage in feed ingredients in parts of north Bihar appears to be significantly high (73.5%). The present study illustrates the facts with special reference to Aspergillus flavus, A. parasiticus (elaborating aflatoxins) A. ochraceous, Penicilium viradicatuin (elaborating ochratoxins) and A. versicolor (elaborating sterigmatocystin). The other strains already known for their toxigenic potentials that appeared on the present substrates included A. niger, A. fumigatus, A. candidus, P. islandicum, Rhizopus spp. and Mucur spp. Studies indicate that the prevalent climatic factors like temperature and relative humidity facilitate a congenial condition almost all through the year and in particular during summer and monsoon months. But water content of the substrates is a vital factor that further accelerates the pace of mycobial spoilage. A thorough sun-drying of the agricultural commodities before prolonged storage to bring water content below the "low risk limit" may significantly reduce the incidence of molds.

Sustainable livelihood approach of prawn production and marketing systems in Mymensingh, Bangladesh

An investigation was carried out in Phulpur upazila, Mymensingh to examine the current production practices of freshwater giant prawn, Macrobrachium rosenbergii and its marketing systems with sustainable livelihood approach. The livelihoods of a considerable number of rural poor are associated with prawn production in Phulpur upazila. Based on a sample of 50 farmers, about 94% farmers were found to culture prawn with fish in their ponds. Only 4% and 2% farmers were found to culture prawn-fish-dike crops and only prawn respectively. Prawn marketing is almost exclusively a preserve of the private sector where the livelihoods of a large number of people are associated with its distribution and marketing systems. The market chain from producers to consumers passes through a number of intermediaries. About 40% of the produced prawns are exported and the rest 60% are sold to local markets. The price of prawn depends on quality, size and weight. The average farm-gate price of prawn varied from Tk. 110 to 160/kg, whereas it's [sic] market price varied from Tk. 150 to 350/kg. Most of the farmers and traders have improved their socio-economic conditions through prawn farming and marketing activities. However, concerns arise about the long-term sustainability of prawn farming and marketing systems due to lack of technical knowledge of prawn farming, poor road and transport facilities, higher transport cost, poor supply of ice, lack of cash and credit facilities. It is therefore essential to provide institutional and organizational support and credit facilities for sustainable prawn production and marketing systems.

Copper-nickel alloys for marine aquacultural engineering

Engineering developments, problems of marine corrosion, fouling and practical innovative applications of copper-nickel alloys in comparison with other materials for marine aquacultural engineering are presented. Coefficient of drag and hydrodynamic force acting on nylon and polyethylene net enclosures have shown a four-fold increase of force in four months at the Cochin harbour due to fouling. Corrosion behaviour of copper-nickel and other copper base alloys are also presented. Effects of copper additions to culture water are reviewed.

Aquaculture potential of ornamental fishes of Uganda

Preliminary studies undertaken to investigate the availability of ornamental fish species in Uganda’s natural water systems, revealed significant abundance of coloured fishes in Uganda’s water systems including the Kyoga and Victoria Lake system. These species are able to breed in captivity and to feed on artificial diets in ponds and glass tanks. The species are attractive and are highly marketable. These observations indicate the potential to culture ornamental fishes as away of diversifying the range of aquaculture species, a means to generate income and to improve livelihoods in Uganda.