61 research outputs found

    लिपोपयूसिन पर्यावरण प्रदूषन का जौव सूचक

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    On the occurrence of Parapenaeopsis stylifera in the stake net catches at Cochin bar mouth

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    The stake net fishery study at the Cochin bar mouth revealed good quantities of the species have been noticed in the catches in certain months and the significant species is reported in this study.P. stylifera was contributed to 1.2, 1.4, 5.2 and 20.6% of the total penaeid prawn catches in February, May, June respectively during the year September, 1987. The percentage composition during 1988 in the months of February, July and September was 1.5, 0.4 and 31.3 respectively.Occurrence of P. stylifera which does in the stake net catches near the Cochin bar mouth during the monsoon and post-monsoon periods is interesting from the point of view of the local movement of the species and requires further studies based on intensive sampling

    Seasonal fishery for Parapenaeopsis stylifera with comments on its possible recruitment along the coasts of Trivandrum, Kanyakumari and Thirunelveli Districts, South India

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    Though the prawn, Parapenaeopsis stylifera does not contribute much to'" the fishery along the south-east coast of India, its abrupt seasonal appearance during July~November along the coasts of Thirunelveli, Kanyakumari and Trivandrum, which amounted to about 1,614 t during 1981-86 seasons, is of great interest from the point of view of its biology and behaviour. Of the two major trawling grounds off Thirunelveli. Manappad Madai sustains a good seasonal fishery for the species, the landing in 1978 being 163 t. However. fishery to the north of Manappad along the south-east coast is of lesser magnitude and does not show any seasonal pattern of occurrence. It is interesting to note that in comparison with the fishery for the species at Neendakara in the south-west coast, the fishery off Manappad shows higher size-frequency distribution with more mature specimens and the peak season occurs in the months of October-November. These facts possibly indicate the movement of the species towards south from Neendakara and to further north upto Manappad, round the Cape Comorin as recorded in the case of Penaeus indicus

    Histological and morphological changes associated with ovarian development of speckeled shrimp Metapenaeus monoceros (Fabricius, 1798) conservation and management

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    Histological techniques and gonadosomatic index (GSI) were applied to validate macroscopic classification of ovaries in Metapenaeus monoceros. The five ovarian maturity stages based on gross morphology were correlated with those based on histomorphology viz., pre-vitellogenic, early vitellogenic, late vitellogenic, vitellogenic and spent. Mean values of GSI increased from 0.353 (immature ovary) to 6.98 (fully mature), thus recording a 20-fold increase. Pre-vitellogenic ovary contained primary oogonial cells, secondary oogonial cells and pre-vitellogenic oocytes. Early vitellogenic stage was characterized by the dominance of perinucleolar oocytes. Folliculogenesis commenced during this stage. Late vitellogenic and vitellogenic ovaries were characterized by rough granular cytoplasm which was fully eosinophilic due to accumulation of yolk and the mean ova diameters during these stages were 170 μm and 230 μm respectively. Cortical rods, which are characteristic features of fully mature oocytes of penaeid shrimp were not encountered during the present study in any of the oocyte development stage

    Effect of sublethal copper on growth efficiency of the shrimp Metapenaeus dobsoni (Miere)

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    In this investigation, an attempt is made to elucidate the effect of copper sublethal concentrations, on the energy conversion and growth efficiency of a commercially important Penaeid shrimp Metapenaeus dobsoni (Miere
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