Papers by Amararatne Yakupitiyage
SIL Proceedings, 1922-2010, 2002
Asia-Pacific Journal of Rural Development, 2009
Socioeconomic study was conducted in the target fishermen community in Maharashtra, India. The su... more Socioeconomic study was conducted in the target fishermen community in Maharashtra, India. The survey revealed that lack of proper drying technology was reflected by weighted mean index. Fishermen strongly felt the need for improvement in the current drying practice as there is high demand for the dried fish products. It was found that the dried Indian mackerel (Rastrelliger kanagurta) from local market showed highest moisture, salt and water activity in the samples. The variation of biochemical contents and bacterial counts increased significantly (P<0.05) after 43 days of storage period. The fishermen are keen to introduce solar-biomass hybrid dryer, which will improve dry fish quality.
International Journal of Food and Fermentation Technology, 2015
Drying of mackerel was conducted using solar biomass hybrid tunnel dryer (S-BHTD) and open sun dr... more Drying of mackerel was conducted using solar biomass hybrid tunnel dryer (S-BHTD) and open sun drying (OSD) at air temperatures 32.4-57.7 degreeC, relative humidity of 23.9-85.8% and air flow rate 0.20-0.6 ms-1. Solar radiation ranged between 287-898 Wm-2 during the experimentation. During the night time, drying was carried out by combusting biomass. The fresh mackerel dried in experimental dryer and in open sun drying achieved the final moisture content < 17% (w.b.). The drying time required in S-BHTD was 21 h. The overall drying efficiency of the solar-biomass hybrid tunnel dryer was estimated to be about 5.42 during fish drying. S-BHTD significantly influenced the biochemical properties of dried mackerel. Mackerel dried by using S-BHTD showed very high corresponding coefficients of determination, where all R2 were greater than 0.85, except histamine value. In experimental dryer, microbial growth was not found except TPC (< 30 cfu/g) which was within the acceptable limit. Contour plots of dried mackerel in S-BHTD dryers also showed that for all the sensory attributes examined, panelists preferred more the fish dried with S-BHTD than OSD. The optimum points for all sensory attributes of dried mackerel evaluated at temperatures ranged from 45-55 degreeC for 20-30 h. Biochemical, microbial analysis and sensory evaluation showed that the dried mackerel remained acceptable after 120 days of storage at ambient temperature. The data showed that the drying in S-BHTD resulted in high quality dried mackerel. The study suggests that the experimental dryer could be used successfully to produce high quality dry fish.
An experiment was conducted to evaluate the possibility of using inorganic fertilizer triple supe... more 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 supplementa...
Macrobrachium rosenbergii is one of the most important and economically farmed prawn species in T... more Macrobrachium rosenbergii is one of the most important and economically farmed prawn species in Thailand. The major farming areas are situated in the central Thailand, especially southwest of the ChaoPhaya River Basin. One of the major constraints for culturing this species is white tail disease (WTD), which caused by Macrobrachium rosenbergii nodavirus (MrNV).Occurrence of this disease in several countries such as Taiwan, French West Indies, China and India has been reported. We are interested in exploring the incidence of MrNV infection in giant freshwater prawn farms in the central Thailand. Method & Materials: A PCR test kit, titled Ezee-Gene MrNV RT-nested PCR (MrNV test kit), was developed to detect MrNV infections in freshwater prawns (Thai partial patent number 0803000211). This test kit has the ability to differentiate the level of MrNV infection i.e. severe, moderate and light infection, which is indicated by the number of bands on gel electrophoresis. A total of 131 prawns were randomly collected from hatcheries and ponds in central Thailand from September 2007 to July 2008 and checked for the MrNV infection using the above test kit. Results & Conclusion: Forty-nine samples (37.40%) were MrNV positive. This included 8 broodstock samples and 15 post-larvae that showed a light MrNV infection, whereas 26 juvenile samples had severe MrNV infection. There were no gross signs associated with WTD in both post-larvae and broodstock with light MrNV infection. However, only a few post-larvae with MrNV infection survive in grow out ponds.This study confirmed the incidence of MrNV disease outbreaks in the freshwater prawn farms in central Thailand. The information obtained from this study will be used to develop a quarantine method and to disseminate information on suitable farm management practices to farmers.
Polish Journal of Environmental Studies
Heterogeneous individual growth and cannibalism are major impediments to farming giant freshwater... more Heterogeneous individual growth and cannibalism are major impediments to farming giant freshwater prawn (GFP), Macrobrachium rosenbergii, and growing GFP individually in compartment farming units could eliminate both hindrances. This study conducted two pioneering trials to evaluate a newly designed indoor compartmental grow-out system for GFP. The first trial was designed to investigate the potential use of three commercial microbial supplements (two Bacillus spp. and one photosynthetic bacteria) for water treatment. The results of ammonium removal efficiency showed that the bacterial supplements with Bacillus spp. had the highest ammonia removal efficiency of 91.73% and 90.57%, respectively, compared to the commercial photosynthetic bacteria (86.69%). The second trial evaluated the effect of four water flow rates at 1, 2, 3, and 4 L/min on the growth performance of GFP juveniles. The mean weight gain of the prawns grown in the compartments subjected to the flow rates of 1 L/min and 2 L/min (11.57±0.2 g. and 11.46±0.5 g) was significantly higher than the prawns grown in compartments where the water flow rate was set at 3 L/min and 4 L/min (9.91±0.55 g and 9.65±0.45 g). These results suggest that administration of Bacillus strain in the rearing water and optimal flow velocity confer beneficial effects in vertical compartment culture of GFP.
management systems in Bangladesh to introduce cage culture for resource-poor fisheries
Can Tho University Journal of Science, 2016
Phytate is the main storage form of phosphorus (P) in many plants, but phytate-bound P is not ava... more Phytate is the main storage form of phosphorus (P) in many plants, but phytate-bound P is not available to monogastric or agastric fish animals. Phytase, an enzyme specific to hydrolyze indigestible phytate, has been increasingly used in fish feed during the past two decades, mainly in response to heightened concerns over P pollution to the aquatic environment. Since global phosphate reserves are not renewable, phytate-P as an alternative and economical P source can be effectively converted to available-P by phytase. The capability of this enzyme to enhance bioavailability of P and reduce P load is well documented. Phytase supplementation also leads to improved availability of other minerals and trace elements. Nevertheless, there is still no consistent conclusion that phytase could enhance protein and energy utilization. Studies in amino acid digestibility after phytase supplement are mutative and the underlying mechanisms have not been fully understood. Because phytase is very sensitive to pH and temperature, the utilization of phytase in fish feed is still on its first stage compared with that of in poultry and swine feed. A wide variety of phytases were discovered and characterized in order to find the optimum enzyme which is stable in application, resistant against high temperatures, dust-free, and easy to handle. Initial steps to produce phytase in transgenic plants and fish animals are also undertaken. In this review, the authors focus on comparing properties of phytase from different sources, examining the effects of phytase on P utilization and aquatic environment pollution, meanwhile providing commercial potentiality and impact factors of phytase utilization in fish feed.
Journal of Lake Sciences, 1999
Fisheries Management and Ecology, 2000
A total of 5488 ha of oxbow lakes in Bangladesh has recently gained importance as a potential fis... more A total of 5488 ha of oxbow lakes in Bangladesh has recently gained importance as a potential fishery resource. The growing need to utilize this resource to a fuller potential requires consideration of cage culture by resource-poor fishing communities as a compliment to existing stock enhancement programmes. In the present study, the existing management systems of eight lakes are reviewed. Water quality was analysed with reference to the largest lake, i.e. Lake Baluhar. During the present study, > 100 cm transparency indicated the suitability of a lake for cage culture. Other water quality parameters, especially dissolved oxygen, ammonia and nitrite concentrations, also indicated suitability for cage culture. Non-fisheries activities, such as the use of agricultural pesticides in the lake catchment and jute retting in its basin, were identified as the most harmful to fish by the majority of the fishermen. An integrated pest management programme using rice±fish based rearing systems in the lake catchment is recommended. It is further recommended that a unified management system should replace the existing dispersed systems under different management bodies. k e y w o r d s : Bangladesh, cage aquaculture, lake management, oxbow lake.
Aquaculture International, 2007
One hundred and two brackish water shrimp farms in Shyamnagar Upazila of Satkhira District, Bangl... more One hundred and two brackish water shrimp farms in Shyamnagar Upazila of Satkhira District, Bangladesh, were surveyed to study their costs and returns. Key data were collected, using a questionnaire survey from January to August 2002. Profitability of operations was affected by fluctuating yields and prices due to diseases, and generated economic risk. The average total cost of production per hectare was 63,437.57 Bangladeshi taka (tk) (US$1,084.40/ha). The farmers achieved a variable yield of black tiger shrimp (Penaeus monodon), ranging from 7.48 kg/ha to 455.03 kg/ha, with a mean yield of 146.39 kg/ha, through multi-stock and multi-harvest methods. The gross and net incomes per hectare were tk49,999.87 (US$854.69) and tk40,307.04 (US$689.01), respectively. Of the total biomass, 44% came from P. monodon, while the rest (23% and 33%) came from other shrimp and finfish respectively. The return to total cost of P. monodon was a negative profit (tk0.78).
Bacterial infection in aquaculture is mainly controlled by the use of antibiotics. However, indis... more Bacterial infection in aquaculture is mainly controlled by the use of antibiotics. However, indiscriminate use of antibiotics is undesirable, as this often leads to the development of drug resistance and therefore to a reduction in the efficacy of drugs. There is urgent need to look for cheaper and more environmentally friendly alternative approaches to improve the immune system of fish than can act as stimulators to control diseases for sustainable aquaculture. In this study, bioactive extracts from five herbs were extracted using aqueous, chloroform and ethanol as solvents. Antimicrobial activity of aqueous extracts of Aegle marmelos, Emblica officinalis & Moringa oleifera, chloroform and ethanol extracts of Azadirachta indica & Toona sinensis were assessed against S. agalactiae Biotype 2 by using disk diffusion assay. The minimum inhibitory concentrations (MIC) of the herbs were determined by using well diffusion method. Aqueous extract of M. oleifera leaves resulted highest anti...
Aquaculture Research, 2021
The Asian seabass Lates calcarifer mostly familiar as barramundi or seabass is a commercially imp... more The Asian seabass Lates calcarifer mostly familiar as barramundi or seabass is a commercially important species. Asian seabass is naturally distributed in the Indo-west Pacific region and cultured from the Persian Gulf, Arabian Gulf, southeast Asia and Australia (FAO, 2020). Asian seabass is extremely carnivorous and can tolerate high salinity variations (Rimmer and Russell, 1998). High fecundity, captive breeding and rapid growth rate make this species a suitable candidate for aquaculture (de Jesus-Ayson &amp; Ayson, 2014; Venkatachalam et al., 2018). The ability to tolerate crowding, high turbidity, varying salinities and temperature makes it a relatively hardy species (Boonyaratpalin, 1997; Yue
Australasian Journal of Ecotoxicology, Jul 1, 2004
A preliminary ecological risk assessment approach was used to determine the potential ecological ... more A preliminary ecological risk assessment approach was used to determine the potential ecological consequences of pesticide use for aquatic systems in Thailand. Using a two-tiered approach, data from participatory community appraisals and household surveys were employed to assess exposure risk. Two sites representing monocrop (tangerine) and mixed-crop (vegetables and fruit) systems were studied. In the first tier the Predicted Environmental Concentration (PEC) is based on an 'extreme worst case'loading scenario. ...
Aquaculture Nutrition
All-female giant freshwater prawn Macrobrachium rosenbergii has a significant growth limitation d... more All-female giant freshwater prawn Macrobrachium rosenbergii has a significant growth limitation due to its early sexual maturity. A 60-day trial was carried out to determine the effect of beta-agonist, ractopamine hydrochloride (RAC), on the growth performance, body composition, and gonadal maturation of all-female prawns. Prawn juveniles ( 4.39 ± 0.40 g initial weight) were stocked at 10 prawns/m2 in 15 plastic tanks (1000 liters each) in a completely randomized design with four treatments and a control (0, 5, 10, 15, and 20 mg/kg) in triplicate. The significantly ( p < 0.05 ) highest values of final weight, weight gain, daily weight gain, and specific growth rate (SGR) were observed in the female prawns fed with the diet containing 10 mg/kg RAC, while the lowest values were found in the control tank. Similarly, survival rate, feed conversion rate (FCR), and condition factors were observed among all treatments, which were significantly better than the control (0 mg/kg). Signifi...
ZBW - Leibniz Information Centre for Economics, 2015
Aquaculture Research, 2022
management systems in Bangladesh to introduce cage culture for resource-poor fisheries
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Papers by Amararatne Yakupitiyage