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Subject: Fisheries × Author: KAU × End date: 2005 × Start date: 2005 × Type: Thesis × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    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; KAU; Rajasekharan Nair, J
    Most of the conventional fishery resources of the continental shelves of the Indian EEZ are either optimally exploited or over exploited. Exploitation of the unexploited nonconventional finfishes will be a solution to meet the growing demand for fish in the country. The present study based on the exploratory fishing data of M.F.V. Matsya Varshini during the period of February 2004 to April 2005 indicates the presence of nonconventional finfish resources along the deeper waters (100-500 m) off the south west coast of India (70-100N lat.). 97 species belonging to 16 orders, 51 families, and 78 genera recorded during the study points to the rich diversity of nonconventional finfishes in the study area. Nonconventional finfishes formed 72% of the trawl catches obtained during the period under study. Distribution pattern and abundance of the nine species/species-groups are presented and discussed. Area-wise 70-80N lat. (200-500 m depth zone) has been found to be more productive and the abundance has shown a decreasing trend towards the northern latitudes. Results of the study confirm that bathymetric difference is the key factor for the distribution and abundance of deep-sea finfishes. Depth wise, the 200-300 m zone has been found to be more productive with a relative abundance of 1829.7 kg.h-1 of deep-sea finfishes. Trichiurus auriga with a relative abundance of 146.78 kg.h-1 dominated among finfishes, followed by Psenopsis cyanea with an average relative abundance of 144.38 kg.h-1. Existence of seasonal variation and difference of habits of the nonconventional finfishes have been observed during the study. Results of the length frequency studies carried out for seven important nonconventional finfish species are discussed. A standing stock of 98442.17 tonnes estimated for the nonconventional finfishes from the study area makes them a potential resource for commercial exploitation. Biomasses of the 9 species/species-groups of nonconventional finfishes estimated separately are also presented. Need of an organized survey of nonconventional deep sea finfishes covering the entire Indian EEZ by using different types of gears has been highlighted.
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    ThesisItemOpen Access
    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; KAU; Jose, T M
    Discovery 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.