Economics of pond fish culture in some selected areas of Bangladesh

A simple costs and return analysis was done to determine the profitability of pond fish culture in three selected thanas namely Nertakona Sadar, Purbadhala and Kendua under Netrakona district. Cobb-douglas production function model was used to estimate the contribution of key variables to the production process of pond fish culture. It was found that cost of pond fish production was Tk. 10,103/ha/yr and the per hectare fish yield was 943 kgl/yr and the average gross and net return were Tk. 49,515 and Tk. 39,412 respectively. It was found that medium and small farms had the higher yield because of efficient use of production inputs compared to large farms. It was also observed that ownership of pond, number of species and human labour had negative impact on pond fish output, while depth of pond water, farm size, fish seed, fertilizer and artificial feed had significant positive effects on pond fish output.

Laboratory culture of Moina with organic ana inorganic fertilizers

An experiment was conducted in the laboratory condition to determine the effect of organic (poultry drop, cow dung and mustard oil cake) and inorganic fertilizer (urea) on production, reproduction rate and maturation time of Moina species. Production rate was also determined in both aerated and non-aerated system in plastic containers with carrying capacity of 2.5-liter each. Total production was significantly higher in both aerated (2475 individuals/2.5 l water) and non-aerated (3253 individuals/2.5 l water) containers using poultry manure compared to other fertilizers. Moreover, the reproduction rate and maturation time in poultry drops showed distinct efficacy in Moina species. Reproduction rate of 11 individuals was the maximal while lowest maturation time was found 78 hours. Reproduction and maturation were induced surprisingly in test tube where the aeration system was absent.

Culture potentials of mola (Amblypharyngodon mola ), chela (Chela cachius) and punti (Puntius sophore) under monoculture system

To assess the production potentials of small indigenous fish species (SIS) in semi-intensive monoculture system, an experiment was carried out with Amblypharyngadan mala, Chela cachius and Puntius sophore. Three treatments each with three replications were tested with mola, chela and punti individually and the stocking density of each species was 100,000/ha. Organic fertilizer was applied to the ponds at the rate of 1,000 kg/ha at fortnightly and rice bran was supplemented daily at 3% of the total fish biomass. Partial harvesting was made after three months of stocking. Gross production of 805±52.94, 1,120±41.62 and 509±48.81 kg/ha, respectively for mola, chela and punti over a period of six months were obtained. The yield of punti was found to vary significantly (P < 0.05) from that of mola and chela.

Economics of pond fish culture under BRAC supervision in Mymensingh, Bangladesh

This study examines the relative profitability of pond aquaculture (polyculture and monoculture of silver barb) under BRAC supervision in Trishal Upazila, Mymensingh district in Bangladesh. The results of the study showed that polyculture was economically more rewarding than monoculture, though both the farming activities were profitable. Production function analysis proved that inputs such as fingerlings, fertilizer, feed and manure had positive impact on output. Human labor and insecticides were over used. The coefficients had expected signs and were found to be very significant.

Effects of iso-nitrogenous and iso-phosphorus fertilizers as nutrient sources on carp polyculture in Bangladesh

A 120 day long experiment was conducted to find out the effects of cow manure with urea and triple super phosphate (CUT), poultry manure with urea and triple super phosphate (PUT) and cow manure with poultry manure (CP) having similar quantities of nitrogen and phosphorus on pond productivity and fish yield. The stocking fish were rohu (Labeo rohita), catla ( Catla catla) and mrigal ( Cirrhinus mrigala) in each treatment pond at the rate of 10000/ha. All ponds were fertilized fortnightly at the rate of 4000 kg/ha cow manure with 62 kg/ha urea and 65 kg/ha TSP, 2700 kg/ha poultry manure with 62 kg/ha urea and 16 kg/ha TSP, and 4000kg/ha cow manure with 2700 kg/ha poultry manure for the treatment CUT, PUT and CP respectively. Each treatment contained an iso-nitrogen and iso-phosphorus of 56 kg and 46 kg respectively. Though the physico-chemical parameters were more or less similar in all ponds, the chlorophyll-a content and abundance of total plankton were significantly higher (P< 0.05) in the ponds receiving the fertilizer treatment of PUT than those of other treatments. Final growth as well as per unit production of fish of treatment PUT (1773 kg/ha) was significantly higher (P< 0.05) than that of treatment CP (1528 kg/ha) followed by that of treatment CUT (1336 kg/ha). The over all results showed that poultry manure with urea and triple super phosphate proved to be superior to cow manure with urea and triple super phosphate, and poultry manure with cow manure, even when nitrogen and phosphorus content was similar, in carp polyculture system under prevailing conditions.

Alternative phosphorus sources for formulated fish feed

An experiment was conducted to evaluate the possibility of using inorganic fertilizer triple super phosphate (TSP), inorganic fertilizer 16:20 (a 16:20 grade fertilizer contains 16 percent N and 20 percent P20 5), rice-bran and duck-manure as phosphorus sources in formulated fish feed for Nile tilapia ( Oreochromis niloticus). Experiment was conducted for a period of 2 months in net-cages suspended in fertilized earthen ponds and all male sex-reversed Nile tilapia (9.39- 10.37 g) were used in the experiment. Seven treatments including one non-feed treatment were used in this experiment. Treatment 1 (non-feed), treatment 2 (-P) where fish fed with phosphorus non-supplemented diet acted as control 1 and treatment 3, 4, 5, 6 and 7 where fish fed with 3% di-calcium phosphate (DCP), 3% triple supper phosphate (TSP), 7% 16:20 inorganic fertilizer, 30% rice-bran and 30% duck-manure supplemented diet, respectively. Results showed that the TSP and 16:20 grade inorganic fertilizer supplementation in diets as phosphorus sources were equivalent to DCP (Di-calcium phosphate) supplementation in terms of growth performance, feed utilization efficiency and final body composition of Nile tilapia. Ricebran and duck-manure were not found as good phosphorus sources.

Input-output relationship and economics of pangas monoculture and carp-pangas polyculture in two districts of Bangladesh

An attempt was made to study the input-output relationships and economics of pangas monoculture and carp-pangas polyculture in Bangladesh. By analyzing the data collected from 50 pangas farms and 55 carp-pangas farms, the study has investigated the production systems of two technologies and the effects of fingerling stocking and applications of feed and fertilizer on fisheries income. The data were collected from the fishermen of Trishal and Bhaluka of Mymensingh district, and Kahaloo and Adamdighee of Bogra district during 2001-02. For pangas monoculture, the stocking density was 31,561 per ha while it was 55,017 per ha in carp-pangas polyculture. Most of the farmers used urea, TSP and lime before stocking. Rice and wheat bran happened to be the most common feed ingredients for both types of culture in general. Other important ingredients used were mustard oil-cakes, rice polish, wheat flour, fish meal, bone meal, soybean meal and poultry litter. In terms of quantities, rice bran and wheat bran dominated the farmers list. Rice and wheat bran together constituted about 60% of all studied feeds. Feed cost constituted 59.13% of total costs for pangas monoculture and 67.44% for carp-pangas polyculture. Per ha productions of pangas and carp-pangas in a single culture cycle were 15,508 kg and 19,745 kg, respectively. Per ha gross profits were estimated to be Tk 310,311 and Tk 464,418 for pangas monoculture and carp-pangas polyculture, respectively. Net profit appeared to be Tk 264,216 per ha for pangas monoculture and Tk 416,509 per ha for carp-pangas polyculture. The BCRs calculated were 1.46 and 1.68 for monoculture and polyculture, respectively. The break-even costs per kg of fish were estimated at Tk 36.93 for pangas and Tk 30.93 for mixed species which was much lower than the prices the producers received. Break-even productions were estimated at 10,702 kg per ha for pangas monoculture and 11,784 kg per ha for carp-pangas polyculture. Fingerling and feed cost, and pond size significantly explained the variation of income from pangas monoculture. These factors have significantly influenced the income from the crop. Functional analysis shows that 1% increase in the feed cost might increase 0.51% of pangas income and 0.41% in carp-pangas income. No other inputs had shown this much of responses to increasing income from a fish.

A study on rural women's empowerment through participation in aquaculture

The study was undertaken to understand the rural women's (i) extent of participation in some selected aquaculture practices and (ii) extent of empowerment through participation in aquaculture program. Data were collected from 200 selected rural women of two districts - Sherpur and Kishoreganj. Each of the families where the selected rural women who were involved in aquaculture under the supervision of two partner NGOs of DSAP, namely- Foundation for Human Development (FHD) and Center for Rural and Environmental Development (CRED). Both conventional and participatory methods of data collection were employed where structured questionnaire and Focus Group Discussion (FGD) were used as the tools. The data collection procedure took five-months spanning from September 2004 to January 2005. Appropriate scales were developed and used in order to determine the focus variables of the study, while most analyses regarding women empowerment were done using 'before' and 'after' method. Empowerment of women was measured by five dimensions such as decision making ability, spending ability, social participation, cosmopoliteness, access to assets and resources. The ten selected aquaculture practices were: fish feeding, eradication of aquatic vegetation from fish pond, disease detection, application of fertilizer, liming, harvesting of fry and fish, fish stock management, pond excavation, use of insecticides, and sale of fry and fish. The study also aimed at determining some selected characteristics of rural women and determining relationship between their extent of empowerment and the selected characteristics. The characteristics of rural women included: age, personal education, average family education, family size, family farm size, area under aquaculture, extension media exposure, training exposure, knowledge in aquaculture, and family income. The findings revealed an overall low level of participation by rural women in aquaculture activities. However, significant level of improvement was identified regarding overall status of empowerment during the course of participation in aquaculture program under DSAP.

Preliminary biological evaluation of some formulated feeds for P. monodon

Rice bran is widely used by fish farmers as supplementary feed while soybean cake is used both as feed and as fertilizer in fishponds. Both fish meal and shrimp head have been found acceptable as feed ingredients. However, not much is known of the acceptability and efficiency of a mixture of these ingredients as feed for Penaeus monodon larvae. Ninety 127-day old P. monodon were measured for length and weight and were randomly divided into nine aquaria each containing 20 liters of water. These were fed 'lampirong' for two months previous to the study. There were three replications for each treatment. Length, weight, and survival rates were used to compare the efficiency of the diets. Weighed amounts of pellets equivalent to 100% of the body weight were fed during the first three days and reduced to 50% thereafter. A stopwatch was used to determine the length of time that elapsed before the shrimps would approach the pellet. Ten shrimps approximately 4 months in age were placed in 10 liters of water in a 25-liter aquarium. Two grams of each pellet type were placed simultaneously on opposite sides of the aquarium. The time that elapsed from the moment the pellets sunk to the bottom up to the time that any one shrimp approached the pellets was recorded. The group fed the imported pellets gained the most. Those fed FP-2s-77 elongated faster than those fed FP-1s-77. Survival rate of those fed FP-2s-77 was 37% while those fed imported pellets was 73%. Both 1s and 2s pellets disintegrated in water easily but the imported pellets were stable even after six hours in water. The attractability test for the pellets showed that the prawns were more readily attracted to the pellets 1s and 2s than to the imported pellets.

Mass culture of marine diatom Skeletonema costatum (Greville) Cleve collected from the Bay of Bengal

The growth of Skeletonema costatum in two artificial nutrient media was studied using various culture vessels. Skeletonema costatum was collected from the Cox's Bazar coast around the Bay of Bengal. Different growths stages i.e. lag phase, exponential phase, prestationary phase, stationary and death phase were observed during the culture period. The number of cells increased during the active division period and decreased after the beginning of the prestationary phase. The average densities of S. costatum in primary and secondary cultures were 0.55 x 10 super(6) cells mlˉ¹ and 0.93x10 super(6) cells mlˉ¹, respectively. In mass culture of S. costatum two, types of media were used. Highest cells densities of S. costatum cement tank culture were recorded 1.23x10 super(6) cell mlˉ¹ and 0.78x10 super(6) cells mlˉ¹ in their respective f/4 medium and commercial fertilizer medium. In the cement tanks culture fertilizer medium was found to be the best medium for mass culture of S. costatum in respect of production efficiency and culture stability.

Modifications in bangus culture

The article presents the milkfish aquaculture techniques in the Philippines modified from the traditional method. These are modular method and silo method, methods on eliminating snails, fertilizer-water replenishment scheme, supplemental feeding and the stunting of fingerlings are also presented.

AQD recommends semi-intensive milkfish culture

Details are given of a system for semi-intensive milkfish (Chanos chanos) vulture recommended by the SEAFDEC Aquaculture Department, under the following headings: 1) Pond preparation; 2) Pest (snails) control; 3) Pest (tilapia and other fish) control; 4) Fertilizer application; 5) Stocking density in nursery ponds; 6) Stocking density in grow-out ponds; and, 7) Water management.

A laboratory study on risk assessment of microcystin-RR in cropland

The persistence time and risk of microcystin-RR (MC-RR) in cropland via irrigation were investigated under laboratory conditions. In order to evaluate the efficiency of the potential adsorption and biodegradation of MC-RR in cropland and the persistence time of MC-RR for crop irrigation, high performance liquid chromatography (HPLC) was used to quantify the amount of MC-RR in solutions. Our study indicated that MC-RR could be adsorbed and biodegraded in cropland soils. MC-RR at 6.5 mg/L could be completely degraded within 6 days with a lag phase of 1 - 2 days. In the presence of humic acid, the same amount of MC-RR could be degraded within 4 days without a lag phase. Accordingly, the persistence time of MC-RR in cropland soils should be about 6 days. This result also suggested the beneficial effects of the organic fertilizer utilization for the biodegradation of MC-RR in cropland soils. Our studies also demonstrated that MC-RR at low concentration (< 10 mu g/L) could accelerate the growth of plants, while high concentration of MC-RR (> 100 mu g/L) significantly inhibited the growth of plants. High sensitivity of the sprouting stage plants to MC-RR treatments as well as the strong inhibitory effects resulting from prolonged irrigation further indicated that this MC-RR growth-inhibition may vary with the duration of irrigation and life stage of the plants. (c) 2007 Published by Elsevier Ltd.

Sorption, degradation and mobility of microcystins in Chinese agriculture soils: Risk assessment for groundwater protection

In the present paper, sorption, persistence, and leaching behavior of three microcystin variants in Chinese agriculture soils were examined. Based on this study, the values of capacity factor and slope for three MCs variants in three soils ranged from 0.69 to 6.00, and 1.01 to 1.54, respectively. The adsorption of MCs in the soils decreased in the following order: RR > Dha(7) LR > LR. Furthermore, for each MC variant in the three soils, the adsorption rate in the soils decreased in the following order: soil A > soil C > soil B. The calculated half-time ranged between 7.9 and 17.8 days for MC-RR, 6.0-17.1 days for MC-LR, and 7.1-10.2 days for MC-Dha(7) LR. Results from leaching experiments demonstrated that recoveries of toxins in leachates ranged from 0-16.7% for RR, 73.2-88.9% for LR, and 8.9-73.1% for Dha 7 LR. The GUS value ranged from 1.48 to 2.06 for RR, 1.82-2.88 for LR, and 1.76-2.09 for Dha(7) LR. Results demonstrated the use of cyanobacterial collections as plant fertilizer is likely to be unsafe in soils. (c) 2006 Elsevier Ltd. All rights reserved.

STUDIES ON THE PURIFICATION AND RECLAMATION OF WASTE-WATER FROM A MEDIUM-SIZED CITY BY AN INTEGRATED BIOLOGICAL POND SYSTEM

The feasibility of an inexpensive wastewater treatment system is evaluated in this study. An integrated biological pond system was operated for more than 3 years to purify the wastewater from a medium-sized city, Central China. The experiment was conducted in 3 phases with different treatment combinations for testing their purification efficiencies. The pond system was divided into 3 functional regions: influent purification, effluent upgrading and multi-utilization. These regions were further divided into several zones and subzones. Various kinds of aquatic organisms, including macrophytes, algae, microorganisms and zooplankton, were effectively cooperating in the wastewater treatment in this system. The system attained high reductions of BOD5, COD, TSS, TN, TP and other pollutants. The purification efficiencies of this system were higher than those of most traditional oxidation ponds or ordinary macrophyte ponds. The mutagenic effect and numbers of bacteria and viruses declined significantly during the process of purification. After the wastewater flowed through the upgrading zone, the concentrations of pollutants and algae evidently decreased. Plant harvesting did not yield dramatic effects on reductions of the main pollutants, though it did significantly affect the biomass productivity of the macrophytes. The effluent from this system could be utilized in irrigation and aquaculture. Some aquatic products were harvested from this system and some biomass was utilized for food, fertilizer, fodder and some other uses. The wastewater was reclaimed for various purposes.