Distribution, biology and behaviour of the giant trevally, Caranx ignobilis- a candidate species for mariculture

Fishery and biology of the giant trevally, Caranx ignobilis exploited along the Tuticorin coast of Tamilnadu were monitored during 2001-2006. Fishery occurred round the year with peak landings during April-August. Spawning and recruitment occur almost round the year with peak during November-December. Young ones are abundant in shallow coastal waters and as grows, they move to deeper waters. Growth parameters, L"' and K are estimated respectively as 143.6 cm and 0.69/year and 'to' as -0.0242 year. Estimates show that they grow fast and attain 73, 108, 126 and 134 cm in total length by first, second, third and fourth year respectively. Their weight increment is also fast and attains 5.5 kg, 16.8 kg, 25.9 kg and 33.7 kg respectively during the period. Stock assessment indicated that the stock at present is over exploited and under heavy fishing pressure. Rearing trial in aquarium tank showed that they are compatible to confined rearing conditions. Based on the distribution and biology of the species, their mariculture potential is discussed.

Culture practices of freshwater giant prawn in some selected areas of Mymensingh

A study was conducted to examine the culture practices of freshwater giant prawn, Macrobrachium rosenbergii in some selected areas of Mymensingh. Based on a sample of 100 farmers from three different upazila, namely Phulpur, Gouripur and Ishwargonj in Mymensingh district, 94% of farmers cultured prawn with fish in their pond. Only 6% of farmers cultured prawn, fish and dike crops for higher economic return. The culture period is typically nine months; hatchery produced post-larvae were stocked from May to June and harvested from November to January. Per hectare production of prawn, 375 kg/yr was very low because the farmers followed simple culture method. Most of the farmers made a profit of Tk. 68,403/ha/yr and the major costs incurred were for purchasing prawn seed and feed. The culture of prawn in pond system is technically possible under different conditions though expansion of small-scale prawn farming mainly depends on reduction of production costs. Future targets could be integration of pond prawn culture with other agricultural activities especially dike cropping and rice production in the monsoon.

HACCP based management system for improving quality of freshwater giant prawn, Macrobrachium rosenbergii

The study was conducted on the present status of HACCP based quality management system of golda, Macrobrachium rosenbergii farms in Fulpur region of Mymensingh. Information was collected on general condition of farms, culture systems and post-harvest quality management. In almost all farms, there is no or inadequate infrastructure facilities such as, road access, electric supply, telecommunications, ice, feed storage facility, vehicle for golda transportation, washing and toilet facilities. The problems associated with sanitation and hygiene was: widespread use of cow dung, poultry manure and construction of open toilet within the vicinity of prawn culture pond. Different grades of commercially available and locally prepared feeds were used for golda culture in the pond. Golda post-larvae (PL) of 40-50 days old were stocked with carp species. The price of golda PL ranged from Tk. 1.00 to Tk. 1.25/piece. The pond size varied from 50 decimal (0.2 ha) to 2.5 acre (1.0 ha) with an average depth of 2-2.5 m. The culture period of golda varied from April-May to November-December and survival rate ranged between 75 and 80%. Production of golda varied from 250-500 kg/acre (625-1,250 kg/ha). Harvested golda were transported to city market within 4 h. Two size grading were generally followed during pricing, e.g. Tk. 500 to 550/kg for >100 g size and Tk. 300/kg for <100 g size. The cost-benefit ratio was found to remain around 1:1.25 depending on availability of PL. Water quality parameters such as, water temperature, pH, dissolved oxygen, total alkalinity and chlorophyll a in five golda farms in Fulpur region were monitored. Water temperature ranged from 29°C to 33°C, dissolved oxygen from 2.28 to 4.13 mg/l, pH between 6.65 and 7.94, alkalinity from 44 to 70 mg/l and chlorophyll a concentration from 61.88 to 102.34 µg/l in the five investigated ponds. The Aerobic Plate Count (APC) of the water sample was within the range of 2.0x10^6 - 2.96x10^7 CFU/ml and of soil samples within the range of 6.9x10^6 - 7.73x10^6 CFU/g. Streptococcus sp., Bacillus sp., Escherichia coli, Staphylococcus sp., Pseudomonas sp. and Salmonella sp. were isolated from pond water and sediment. Different feed samples used for golda was analyzed for proximate composition. Moisture content ranged around 14.14-21.22%, crude protein 20.55-44.1%, lipid 4.67-12.54% and ash 9.7-27.69%. The TVB-N values and peroxide values of feeds used as starter, grower and fish meal were found within the acceptable ranges and samples were free from pathogenic organisms. A training was organized for the golda farmers on HACCP, water quality and post-harvest quality management of prawn.

Improved handling and preservation of freshwater giant prawn, Macrobrachium rosenbergii for producing safe and wholesome products

Studies were undertaken to evaluate the quality changes in freshwater giant prawn, Macrobrachium rosenbergii during various storage conditions of handling and preservation and producing safe and quality products. The samples kept in ice immediately after catch with head-on and head-less condition were found to be acceptable for 6 days and 7 days, respectively. Delaying of icing considerably shortened the shelf-life. The pH value increased from 6.36 to 8.0 after 10 days in ice. The initial average TVB-N value of sample increased from below 10 mg/100 g to 25 mg/100 g with the lapse of storage period. The Ca++ ATPase activity in presence of 0.1M KCl slightly decreased at the end of 10 days of ice storage. Immediately after harvest, initial aerobic plate count (APC) was 2.88x10^6 CFU/g which gradually increased to 1.12x10^8 CFU/g after 6 days in ice storage and showed early signs of spoilage. Initial bacterial genera in the prawn iced at 0 hours were comprised of Coryneform (22.21 %), Bacillus (7.40%), Micrococcus (11.11 %), Achromobacter (48.14%), Flavobacterium/Cytophaga (7.40%), Pseudomonas (3.70%) and Aeromonas (3.70%). During ice storage Coryneforms and Bacillus were always dominating along with less prominent ones - Micrococcus, Achromobacter and Flavobacterium. Studies were conducted on the stability of myofibrillar protein of M. rosenbergii under different storage and pH conditions. The influence of a wide range of pH on the remaining Ca++ ATPase activity of M. rosenbergii muscle myofibrils after storage at -20°C for 2 days, at 0°C for 2 days and at 35°C for 30 minutes demonstrated that ATPase activities were lower in acidic and alkaline pH regions and the activity remained relatively high. Mg++ ATPase activities both in presence and absence of Ca++ remained high at neutral pH compared to those of acidic and alkaline region. The solubility of myofibrillar protein decreased gradually both in acidic and alkaline pH regions. The study also examined the bacteriological quality of freshly harvested M. rosenbergii, pond sediment and pond water from four commercial freshwater prawn farms at Fulpur and Tarakanda upazilas in the district of Mymensingh. The study included aerobic plate count (APC), total coliform count, detection, isolation and identification of suspected public health hazard bacteria and their seasonal variation, salt tolerance test, antibiotic sensitivity test of the isolates and washing effect of chlorinated water on the bacterial load in the prawn samples. APC in sediment soil and water of the farm and gill and hepatopancreas of freshly harvested prawns varied considerably among the farms and between summer and winter season. The range of coliform count in water, gill and hepatopancreas ranged between 6 - 2.8x10^2 CFU/ml, 1.2x10^2 - 3.32x10^2 CFU/g and 1.43x10^2 - 3.89 x10^3 CFU/g, respectively. No coliform was detected in pond sediment sample. Suspected health hazard bacteria isolated and identified from pond sediment, water, gill and hepatopancreas included Streptococcus, Bacillus, Escherichia coli, Klebsialla, Salmonella, Staphylococcus, Pseudomonas and Aeromonas. Bacillus, Salmonella and Staphyloccus [sic], and were found to be highly salt tolerant and capable of growing at 10% NaCl. The antibiotic discs with different concentration of antibiotics were used for the sensitivity test. The organisms were found to be most sensitive against Tetracyclin and Gentamycin.

Production of freshwater giant prawn using over-wintered juveniles for enhancement of farm income and reduction of rural poverty in Bangladesh

Freshwater giant prawn, Macrobrachium rosenbergii fry produced during late season can not withstand low temperature thus the prawn culture programme during winter is hampered. To overcome this problem, late season (August-September) prawn juveniles (0.9-6.8 g) were stocked at a density of 1.43 to 3.57/square meter in 350-476 square-meter ponds in Pabna and Mymensingh districts during October 2000 and cultured till May 2001. Monthly average water temperature during the winter months (December-February) varied from 16 to 22 °C and gradually increased to 32 °C in May. The prawn fry showed fast growth rate and attained an average weight of 60-70 g within eight months including three winter months. Growth compensation was observed during summer months. Survival rate was 60-79%. After extrapolation of the present growth rate more than 1,600 kg/ha production can be achieved in better-managed ponds. Extrapolated cost of production was Tk. 268,000 and 200,000 Tk./ha in two best ponds, sale value was Tk. 644,9146 [sic] and 528,466 and gross profit was Tk. 376,000-410,000, suggesting a higher economic feasibility of farming freshwater prawn with over-wintered juveniles.

Preliminary histological study of the ovarian development of the giant tiger prawn, Penaeus monodon

This study was undertaken to determine structural characteristics within the gonads which might serve as an index to age and longevity and furnish information on the frequency of spawning of an individual.

Preliminary study on the internal genital organ of the giant tiger prawn, Penaeus monodon

This report gives information on the anatomy of the internal genital organs of male and female Penaeus monodon.

Report of the MPA Atlas and the interactive online database portal of the Bay of Bengal Large Marine Ecosystem

This report describes the process and details of developing an interactive online database portal for the BOBLME region.The MPA (Marine Protected Area) Atlas website, created by WorldFish was designed to provide public access to the latest information relevant to marine scientists, managers and conservationists. The main features include; BOBLME MPA database;interactive geospatial maps;and information about important habitats such as coral reefs,BOBLME boundaries and bathymetry.