Structure and seasonal dynamics of the juvenile brown shrimp, Metapenaeus monoceros in the Sundarbans mangrove waters, Bangladesh

The density and temporal distribution of the postlarvae and juveniles of Metapenaeus monoceros in the Sundarbans water were assessed for two years, along with the environmental factors. There is significant monthly variation in the abundance of M. monoceros (P<0.05) with the species most common during the post-monsoon season. The relationship between the water parameters and population structure of M. monoceros is discussed

Investigation on white spot syndrome virus (WSSV) in Penaeus monodon brood, nauplii, post larvae and cultured shrimp in Cox’s Bazar, Bangladesh by using nested PCR techniques

Investigations were carried out between April 2014 to June 2016 for detecting white spot syndrome virus (WSV) in tiger shrimp, Penaeus monodon broods, nauplii, post larvae and cultured shrimp by using nested PCR techniques. The presence viral DNA was observed in shrimp culture farms in Cox’s Bazar. Of 558 grow out shrimp samples tested, 239 (42.83%) were found to be positive for WSSV by PCR assay. Of 91 post larvae collected in adjacent river and canal, 41 (45.05%) were infected with WSSV and 70 juvenile shrimps collected, 45 (64%) of the samples were positive for WSSV infection. Selected shrimp hatcheries in the region also showed continual occurrence of WSSV infection and 149 nauplii were tested, 39(26.17%) were positive for WSSV by PCR assay. In hatcheries, 248 nos. P. monodon broods collected, 125(50.40%) were found positive for WSSB. The average WSSV infection in brood shrimps were increased as 32%, 34% and 69% for the years 2014, 2015 and 2016, respectively. P. monodon broods collected from the deep sea zone, WSSV prevalence was 57% in summer (May), falling to 0% during winter month (November). Many of the brooders and juveniles did not exhibit any external symptoms of WSSV infection, however, following PCR amplification with WSSV detection primers clear products were revealed, indicating the presence of latent infection. Thus, effective prevention and control measures are urgently needed to control the spread of the WSSV disease in the shrimp industry. Diagnostic PCR can be applied to screen for carrier brood stock and shrimp larvae used for shrimp culture

Feasibility of seaweed culture in Inani and Bakkhali coast of Cox’s Bazar, Bangladesh

The study was analyzed physico-chemical parameters of seaweed culture sites and culture feasibility for a seaweed (Hypnea sp.) in Bakkhali and Inani of Cox‟s Bazar coast, Bangladesh. The results obtained by the water salinity, temperature, transparency, pH and DO are very much suitable for seaweed cultivation. The water and soil nutrients of Saint Martin and Bakkhali were also comparable, indicated the suitability of seaweed culture. Seaweed Hypnea sp. was cultured in Bakkhali and Inani along with Saint Martin using 4m x 4m coir rope net attached to bamboo pole for a period of two months in winter. Maximum daily growth rate of 3.21±0.01%/day at 60th day from Saint Martin and minimum daily growth rate of 0.41±0.11%/day at 15th day from Inani was observed. Significantly higher biomass of seaweeds (11.05±0.10 kg fresh wt./m2) yielded in Saint Martin than Bakkhali (p<0.001) and Inani (p<0.001). Bakkhali and Inani could be suitable areas of seaweed culture added a new dimension to mariculture prospect of Bangladesh

Composition and seasonal dynamics of postlarval and juvenile fishes in the Sundarbans mangrove waters, Bangladesh

206-215The composition and temporal distribution of the postlarval and juvenile fishes in five river systems of Sundarbans mangrove water with different salinities were studied. Monthly or fortnightly day time sampling was conducted with a rectangular drag net. Thirty seven species of fish belonging to 27 families were recorded during the 2 years study. Panchax melastigma, Liza parsia, L. tade and Gobiidae were the most abundant fish species/taxa. In the Sundarbans, species diversity and abundance gradually decreased from the freshwater zone to the saline zone. The highest monthly density of 13 species was observed in the Passur river during November. Liza spp. was the most abundant juvenile catch constituting 29.32%, followed by a small fish P. melastigma (20.13%) and Gobiidae (12.98%). No significant variation in abundance of fish species was observed with lunar cycle, although the annual peak was recorded in winter. Fish abundances varied significantly (p<0.05) among months and rivers. Water temperature and salinity were correlated with the most abundant species

Quality aspects of fish silage and fish meal from marine trash fish

158-161For promoting better utilization of by-catches from existing trawI operation in Bay of Bengal, potential of fish silage was evaluated as fish feed ingredient against fish meal. The biochemical composition of raw silage and dried silage is quite similar to commercial fish meal but marked differences are observed in case of laboratory made fish meat The most wanted protein contents were 14%, 52.9% and 64% for silage, dried silage and laboratory made fish meal respectively. After 90 days of storage, only minor changes were detected in the chemical composition. On the other hand, total bacterial count of these product were initially 1.6 x 10(2) cfu/g, 3 x 10(4) cfu/g and 1.7 x 10(5) cfu/g which after 90 days of storage showed 1.5 x 10(4) Cfu/g 2.9 x 10(6) cfu/g and 1.7 x 10(7) cfu/g for silage, dried silage and fish meal respectively. Total yield and production cost also indicate fish silage as a potential fish feed ingredient

<smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="country-region"><smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="place"> Decomposition and seasonal changes in nutrient constituents in mangrove litter of Sundarbans mangrove, Bangladesh </smarttagtype></smarttagtype>

130-135Decomposition of Heritiera fomes, Xylocarpus mekungensis, Bruguiera gymnorhiza and Avicennia officinalis leaf and non-leaf litter was studied using litter bag in Sundarbans reserve forest. During 45 days decomposition experiment both in field and lab, 43-78% weight loss of fresh mass was recorded. Proximate and micro-nutrient concentrations were similar among different classes of leaf and non-leaf litter. Concentrations of nutrient constituents were higher during the monsoon, and winter showed the highest level of heavy metal concentrations in mangrove litter of Sundarbans. Decomposition of mangrove litter resulted in a decrease in lipid content, and increased the metal concentrations, than fresh one

Nutritional composition, yield and consumer response to a semi-fermented fish product prepared from underutilized fish species of the Bngladesh coastline

73-76Nutritional composition, yield and consumers' acceptability of a ground semi-fermented fish product prepared from the underutilized fish species of the Bay of Bengal have been studied. The product was prepared by a traditional semifermentation method, identical for the preparation of "Sheedal shutki", and was subsequently dried in oven, ground, packed in polyethylene bags and stored in ambient condition. Quality in terms of nutritional composition was found comparable to other fish products of Bangladesh. Comparative study on the acceptability of the new product, traditional Sheedal shutki from both Puntius sp. and miscellaneous sea fish species show that the new product is equally acceptable. The taste and flavour of the product was judged to be identical with those of the traditional Sheedal shutki from Puntius sp. and superior to the Sheedal shutki from underutilized sea fish species.Yield study indicated that commercial production can be attempted if the raw fish is available at a cheap price. Overall results of the study show that the product can be easy to handle, transport and store, and can easily be incorporated with the cereal based diet

Assessing recent gradual upsurge of marine captured Hilsa stock (Tenualosa ilisha) in Bangladesh

The anadromous Hilsa shad (Tenualosa ilisha) fishery is the prime single species fishery of Bangladesh that driven by open access system which was selected for this study. Key purpose of this study was to assess the MSY (Maximum Sustainable Yield) in order to review the effectivity of the ongoing management policy of this fishery. For this reason, time series maritime or downstream catch-effort data of the Bay of Bengal were assembled from the Department of Fisheries, Bangladesh. MSY, CPUE and other population parameters were estimated through Surplus Production Models (SPMs) using computer software packages of CEDA, ASPIC and TropFishR. Assessed biological reference points of MSY from the best fitted CEDA package was 282,100 t (R2 = 0.822) for the normal assumptions of the Schaefer and Pella-Tomlinson models. MSY values from the ASPIC packages (324,100 t and 263,500 t; for Fox and Schaefer model) and Schaefer model from TropFishR (345,486t) were larger than the catch in 2017 (278,948 t). The values of F ratio (F/FMSY) for all SPMs were found less than 1 and B ratio (B/BMSY) were greater than 1 that clearly indicate the gradual upsurge of the Hilsa stock. Based on the above findings of BRPs, it also proves the effectivity of the current “Hilsa fishery management action plan” by the authorities. Keywords: Tenualosa ilisha, SPM (surplus production model), CEDA (catch and effort data analysis), ASPIC (A surplus production model incorporate covariates), TropFish

Evaluation of production performance and profitability of hybrid red tilapia and genetically improved farmed tilapia (GIFT) strains in the carbon/nitrogen controlled periphyton-based (C/N- CP) on-farm prawn culture system in Bangladesh

Performance of hybrid red tilapia (Mutant, Oreochromis niloticus × Oreochromis mossambicus) and GIFT tilapia strain (Oreochromis niloticus) in C/N-CP prawn (Macrobrachium rosenbergii) farming system was evaluated at the farmers' pond at Bailor union under Trishal upazilla of Mymensingh district, Bangladesh. The on-farm trial had two treatments: TR and TG (named according to the tilapia strains) with three replications. Six rectangular ponds of varying sizes (400–880 m2) were used for this experiment. Hybrid red and GIFT tilapia stains were stocked with prawn at the stocking densities of 1 tilapia fingerlings (either red or GIFT strain) and 3 prawn juveniles m-2 in both treatments. Bamboo side shoot were posted vertically as periphyton substrate. This resulted in an additional substrate surface area of 1067 m2 for periphyton development equaling 147% of the pond surface area. Considering the body weight of freshwater prawn only, feeding rates were 10% of body weight at the beginning of the study (up to 30 days), and feeding application was gradually reduced to 3% in the last month assuming 80% survival. The abundance of total benthos and periphyton as well as total periphytic biomass were significantly higher (P < 0.05) in TR than TG treatment and they were also differed significantly (P < 0.05) among different months with a decreasing trends (exception to some extent) over the experimental period. The individual harvesting weight, individual weight gain, specific growth rate, Food Conversion Ratio (FCR), survival (%), gross and net yields of prawn were similar in two treatments. In contrast, the GIFT tilapia strain showed a higher (P < 0.05) individual harvesting weight, individual weight gain, specific growth rate ((SGR, % bw d-1), survival, gross and net yields (1935 and 1825 kg ha-1, respectively) combined gross and net yields (2952 and 2784 kg ha-1, respectively), and economic return (3755 US$ with BCR 0.82) than the hybrid Red tilapia