Molecular approach in disease diagnostics and species identification

  • Comparison of PCR and dot blot diagnostic techniques for detection of white spot syndrome virus (WSSV) was made on different tissues of infected P.monodon including eye stalk, eye stalk with eye, gills, cuticle, pleopod, periopods, uropods and telson. The limitation of PCR due to inhibiting factors present in tissues could be overcome with the use of dot blot which gave positive reaction from the DNA extracted from eye stalk including the eye but yielded no amplification by PCR.
  • Structural protein genes of WSSV have been amplified and cloning of the amplified genes is in progress for expression of recombinant proteins for immunodiagnostics.
  • As an approach towards species identification of penaeids, molecular characterization of mitochondrial genes has been carried out from F.indicus, F.penicillatus and F. merguiensis.
  • Expression of RNA dependent RNA polymerase (RdRp) recombinant protein of Macrobrachium rosenbergii nodavirus (MrNV) was achieved for use in immunodiagnostics for virus detection.

Area development and impact assessment

  • Based on LISS III satellite data, the potential area identified for development of brackishwater aquaculture in Krishna district of Andhra Pradesh was estimated to 12,854 ha.  The major land use classes identified were agriculture, aquaculture, mangroves, fallow land, salt pans, settlements and water bodies.
  • Delineation of aquaculture farms using image processing techniques yielded best results with high resolution data. In case of low resolution data, image processing coupled with manual supervision and digitization were found suitable for the delineation of aquaculture farms.
  • Analysis of land use map of Muthupet mangroves and surroundings prepared from satellite data of IRS IC LISS III for the years 1988 and 2005 revealed that in the 75,215 ha of study area, aquaculture development had not been due to conversion of mangrove land.
  • Using IRS LISS III data, the existing land use pattern in and around Punnakayal mangroves of Tamil Nadu was mapped to assess the present status of mangroves and the accuracy assessment was carried out using GPS.  The traditional farms of north 24 Parganas district, West Bengal have also been mapped.
  • Mapping of land use pattern during pre aquaculture and present scenario was carried out in the Corringa mangrove region to assess the impact of aquaculture.
  • The impact of shrimp farming in nine micro watersheds with total extent of 244 was initiated and the boundary of the study area has been imported to visual MODFLOW software for calibration with the data from PWD. The study is ongoing.

Maturation and seed production

  • Successful domestication of kuruma shrimp Marsupenaeus japonicus was achieved under captivity by closing the life cycle within the hatchery and produced up to F6 generation.
  • Obtained viable spawning from natural matured tiger shrimp Penaeus monodon and banana shrimp Fenneropenaeus merguiensis in ponds.  Natural maturation of banana shrimp was also achieved under controlled conditions in the hatchery.
  • Studied the male reproductive biology of P. monodon and F. indicus with a view to maintain reproductive viability under captive condition in the hatchery. The study revealed that sperm quality remained uniform during inter molt and pre molt period and it could be maintained by periodical removal of spermatophore. Continuous captive rearing result in deterioration of sperm quality.
  • Polychaetes are an essential component of the maturation feed for shrimps.  Experimental culture of the tropical marine polychaete Perineries nuntia yielded 300g biomass in four months. Culture of estuarine polychaete Marphysa gravelyi was initiated and in five months of culture in FRP tank the larvae attained the size of 4-12 cm/0.14-1.1 g.
  • Successfully reared larvae of Scylla tranquebarica and S. serrata from first zoea to first crab stage under captive condition and based on the training provided, a private entrepreneur has set up a private mudcrab hatchery.

Agricultural knowledge management unit (AKMU)

  • Monoculture of kuruma shrimp M. japonicus was conducted  in a farmer’s pond at Sirkazhi, Nagapattinam Dist., Tamil Nadu and a production of 1018 kg/ha in 113 days was acheived.  The shrimps attained an average size of 12.5g with a survival rate of 83%.
  • Immunostimulant developed from heat killed bacterial consortia was extensively tested in farmers’ ponds with the clear indication of improved growth and survival.
  • Survey on the use of chemicals and drugs in shrimp farming in Tamil Nadu and Andhra Pradesh was conducted which indicated that the shrimp farmers spend about 7-10% of the total cost of production on chemicals. They are being used without clear understanding of their efficiency and mode of action. Antibiotics are not used in the survey area.
  • By adopting improved traditional culture techniques, P.monodon production in the range of 2.0 to 2.4 t/ha/crop was achieved from tide-fed ponds at Kakdwip.
  • Standardised biosecured zero water exchange farming technology of tiger shrimp P. monodon with consistent production of 3.0 t / ha with more than 80% survival was achieved. Compared to control, the gain in terms of production, survival and FCR were 7.95%, 6.96% and 10.24%, respectively.
  • Under public-private-partnership, culture of banana shrimp F. merguiensis was undertaken in Gujarat and in 160 days, the shrimps attained average size of  27g and registered 80% survival with 903 kg/ha production.
  • Culture of F. merguiensis during low saline post monsoon period at Kakdwip yielded production of 380-525 kg/ha in five months with average final size of 22g.

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