1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Abundance and distribution of the nonconventional deep-sea finfish resources off the south-west coast of India (lat.7-10N)(Department of Fishery Biology, College of Fisheries, Panangad, 2005) Sajeevan, M K; Rajasekharan Nair, JItem Influence of a putative male pheromone on ovarian maturation and ovulation in the freshwater prawn Macrobacterium rosenbergii (de man, 1879)(Department of Fishery Hydrography, College of Fisheries, Panangad, 2005) Smitha Ramakant Gawade; Jose, T MDiscovery of a male primer sex pheromone with a specific stimulatory effect on ovarian maturation and ovulation in the small sized freshwater shrimp Paratya compressa and the prawns Macrobrachium kistnensis and M. idella is considered very significant. In this context, it was the objective of the present study to investigate this aspect in the commercially important giant freshwater prawn Macrobrachium rosenbergii (de Man 1879). Two sets of experiments were carried out using sexually mature females and blue claw males collected from wild. The first experiment (to study the effect of male deprivation on ovarian maturation) had two groups of females. Group I had isolated females (without males) and group II had females cohabiting with males. Ovarian maturation was monitored daily for 60 days. Maturity stages and the number of berried females were noted and average spawning frequency calculated. There was no difference in the percentage of berried females and average spawning frequency between the two groups and hence no evidence for blocked ovarian maturation in isolated females due to the lack of a male factor. The second experiment was done to delineate the role of visual and/or chemical cues on ovarian maturation in M. rosenbergii. Specially designed glass aquaria were used which had three compartments for three groups of females. Group I females were isolated and received only visual signals and no chemical cues from the males. Group II females were cohabiting with males. Group III females were also isolated from males but received only chemical cues from males through a common water circulation. The same parameters as in the first experiment were monitored for 60 days and no significant difference found between the three groups. Histological study also showed normal maturation. The conclusion is that there is no evidence for an ovary stimulating pheromone in M rosenbergii thus adding one more feature to the distinctiveness of this species.Item Infestation of isopode parasites on prawns of the genus Macrobrachium Bate (Palaemonidae) of Cochin region(Department of Fishery Biology, College of Fisheries, Panangad, 2004) Regina Jasmine, M; Jayachandran, K VThe major objective of the research work is to study the taxonomy, species diversity, host specificity, intensity of infestation, length - weight relationship and reproductive biology of bopyrid parasite infesting the genus Macrobrachium Bate, 1868 of the Cochin region. Collections were taken from 3 stations Perumbavoor (Periyar River) and Panangad (Vembanad lake) for a period of 13 months (July 2002 to July 2003) and Champakkara (Vembanad lake) for a period of one year (October 2003 to September 2004). The study revealed that of the five species of Macrobrachium inhabiting water bodies of Cochin region, only two species were found infested with bopyrids. Macrobrachium idella was infested with Palaegyge alcocki whereas M. scabriculum with a new variety, P. alcocki var. novo cochinensis. This shows that bopyrid infestation is species specific. Diagnostic characters of both the parasite species are given in the text. Regarding the intensity of infestation, prawns from the Perumbavoor region of Periyar River had maximum infestation in comparison with other regions (Panangad and Champakkara). The infestation during different months also revealed the same trend. It indicates that infestation is more at the freshwater region than at the estuarine region. Relationships between length and weight of infested M. idella, P. alcocki separated from the host, total length of host and parasite, total length of male and female parasite, carapace length of the host and total length of male as well as female parasite are all statistically significant. . The study has brought out the ways of association of male and female parasites as well as attachment of female parasite to the host. Mature female parasite has been distinguished from the immature. Fecundity studies revealed that the number of eggs produced by the parasite ranges from 8148 (1 cm total length, 0.9 cm total width, 0.12 g total weight) to 29,683 (1.2 cm total length, 1.0 cm total width, 0.168 g total weight). Number of ova per milligram body weight ranged from 67.9 to 185.518 (126.709 average). Relationships between fecundity and total length, total weight, total width and total weight of brood of the parasite are all significant. The chapter on reproductive biology reveals important observations on marsupial brooding, ovulation, embryonic development and incubation, hatching and epicaridea stage of P. alcocki. The last chapter is on the effect of parasitism on the host. Here the aggressive behaviour of infested host, parasitic castration, degeneration of gills and secondary infections are dealt with in some detail.Item Role of putative male pheromoneiIn the ovarin maturation of the fresh water prawn Macrobrachium Idella (Hilgendorf)(Department of Fishery Biology, College of Fisheries, Panangad, 2001) Patil Chandrakant Sitaram; Jose, T MSex pheromones are reported to be present in many crustaceans which mostly have releaser effect on sexual behaviour. The discovery of a male (primer) pheromone with stimulatory effect on ovarian maturation and ovulation has added an important external factor to the basic mechanisms regulating reproduction in fresh water prawns. But studies in these lines are very few in the economically important species of Macrobrachium. Knowledge about this male pheromone will be useful to help or potentiate reproduction and/or extend the breeding period of freshwater prawns, which are of great aquacuItural importance. The present study was carried out in the slender nver prawn, Macrobrachium idella. Seven ovarian maturity stages have been distinguished here. Histological studies of the maturing oocytes helped to understand the changes taking place during oocyte growth and maturation through the progressive maturity stages. Yolk vesicles start appearing in the cytoplasm of oocyte in maturity stage II which is the beginning of vitellogeneis (vitellogenesis I). In stage IV, yolk platelet synthesis starts and 'a peripheral layer of yolk platelets appear in this stage. Later these yolk platelets completely fill the ooplasm through stages V and VI when the ova increase in size enormously. Gonado- somatic index (ovarian index) of different maturity stages was determined and was found useful to differentiate especially the late maturity stages. Ova diameter studies along with the other observations showed a clear picture of protracted multiple spawning in this species with batches of ova undergoing maturation and ovulation in successive maturation cycles. When the females were reared in isolated condition, their ovarian growth was found to be arrested at early stage IV. This restriction of ovarian maturation was found mostly in the second maturation (gonadal) cycle after isolation. But those isolated females which had a common water circulation with males showed normal ovarian maturation and ovulation. Therefore, it can be concluded that a male pheromone exists in this species which is essential for normal ovarian growth and maturation. Another experiment was conducted to find out the tissue source of this putative male pheromone. When these isolated females were exposed to extracts of testis, vas deferens or muscle, both testis and vas deferens extracts were found to stimulate the ovarian maturation and ovulation in isolated females, while the muscle extract (control) was ineffective. This shows that in M idella, the male pheromone is produced by testis and vas deferens or it is produced by testis and transported to vas deferens. Further experiment showed that charcoal extraction destroys the pheromonal activity in testis and vas deferens extract while boiling has no such effect which indicates that the ovary stimulating pehromone in M idella may be a steroidal molecule as reported in some fishes.