Aquacrops of Darbhanga District in north Bihar and their commercial significance

Darbhanga district in North Bihar is characterised by thick alluvial soil, moderately good rainfall, high humidity, ample sunshine and numerous water resources in the form of perennial rivers, tributaries, streams, lakes, ponds, pools and puddles. The aquacrops of this district include several species of commercially important fishes, aquatic cash crops such as makhana (Euryale ferox), singhara (Trapa spp.), lotus, lilly, Khubi etc. and molluscs. This paper highlights the commercial significance of these aquacrops and offers suggestions for their sustained development.

Prospects of integration of aquaculture with animal husbandry and land crop culture in Tripura State

Tripura is a densely populated small state with meagre water resources. 47.51% of the population is constituted by socio-economically backward, illiterate, orthodox, tribal and scheduled castes. Some of them are nomad and a majority of the rest of the population is refugees from Bangladesh, but almost 100% is fish eater. Settlement of tribes in villages, provision of nutritious food and employment therefore calls for proper utilization of every resource they have. The State is poor in water resources but recently has created 21,636.23 ha of new water area. Tripura is rich in pig population, besides poultry birds. Paddy is the main crop cultivated in arable lands. An integration of livestock raising and land based agriculture with pisciculture practices around mini barrages will help in solving the problems to a great extent. The paper is an attempt to outline the prospects of integration of aquaculture with animal husbandry and land based crop culture in Tripura State.

Vertical distribution of molluscs in the intertidal area in and around Mumbai, India

Vertical distribution of intertidal molluscs in and around Mumbai had been studied. Each species has an upper and lower limit of distribution along the vertical intertidal gradient and are concentrated at particular levels or zones where they find optimum living conditions. Zonation of the intertidal area with reference to molluscs at rocky shores of TIFR, Bandstand and NCPA has similarities. However, there is no similarity in zonation among rocky, sandy and muddy shores. Rocky intertidal zones are more diverse and dense in terms of molluscs. The mid and lower littoral zones have rich diversity. The upper littoral zone at some sites, especially Girgaon chowpatty is totally devoid of molluscs due to anthropogenic activities. Gafrarium divaricatum, Nerita oryzarum, N. polita and Neritina crepidularia have established themselves in all three marked zones, indicating their power to adjust with the wide fluctuations in surrounding environmental conditions.

Ecophysiological response of Nerita oryzarum (Recluz), a gastropod, to variations in temperature, pH and salinity

During ecophysiological investigations on an intertidal gastropod, Nerita oryzarum (Recluz), of Mumbai shore, various biochemical changes could be recorded. Glycogen and lipid contents of N. oryzarum were found to decrease, whereas, water content increased with decreasing salinity. The rate of oxygen consumption declined with the decrease in salinity and also in highly acidic (pH 2) as well as highly alkaline (pH 10) sea water. The observed variations in the rate of oxygen consumption and changes in biochemical composition in the animal with changes in salinity, pH and temperature are probably the process of physiological and biochemical adjustments to the fluctuating environmental conditions in the intertidal region.

The marine linefish resources of Moçambique (status, development and future research)

Marine line-fishing is seen to be of major importance to the social well-being and economy of many coastal people of Mozambique. Aspects of the artisanal and semi-industrial fisheries of Mozambique are described and a recent significant increase in effort is noted. Landings are seen to comprise a high proportion of vulnerable, endemic species, several of which are shared with neighbouring South Africa. Trends in CPUE, sex ratios and yield per recruit suggest that future landings may decline if conservative management is not introduced. Strategies for data collection and biological research on key species are proposed.

Migration of fishermen and its impacts on fisheries management on Lake Victoria, Uganda

The purpose of the study was to investigate migratory movements of fishermen on lake victoria.To identify the cuases of fishrmen migration with a view to establishing the paterns of migration;determining season of migration and assessing the impacts of migration on fisheries management and development.

Status of water hyacinth infestation and control in River Kagera

During a regional workshop held in Mukono, Uganda (May 2001) by scientists and technocrats from Kenya, Tanzania and Uganda, working on water hyacinth management under the Lake Victoria Environmental Management Project (LVEMP), it was resolved that a survey of River Kagera be made to study the status of water hyacinth infestation and biological control in the river. Reports at the Mukono Workshop indicated that although Tanzania and Uganda had made serious effort to introduced biological control weevils (Neochefina eichhorniae and Neochetina brucht) on the weed in River Kagera, the level of establishment of biological control in the river was doubtful. Large quantities of water hyacinth biomass drifted down River Kagera into Lake Victoria daily. Similar reports of apparent inability of biological control weevils to fully establish and have effect on water hyacinth in River Nile, especially the Upper Victoria Nile, were also made by Uganda, and large quantities of weed biomass continuously drifted down the Upper Victoria Nile into Lake Kyoga. This was in spite of the successful control of the weed in Lake Victoria between 1998 and 2000

Study of the rocky intertidal communities of central and northern California: Years III and IV

The study objectives are to describe seasonal and successional variation in rocky intertidal community structure; determine the response of rocky intertidal communities to natural and human-induced disturbances and correlate these responses with successional, seasonal, and latitudinal variation; and correlate life history information and oil toxicity data with data from this and other relevant studies. The Year III and IV report is for the third (1987) and fourth (1988) years of a five-year field experimental study investigating two biological assemblages, the Mytilus assemblage and the Endocladia/Mastocarpus papillatus assemblage, that are being studied at six sites along the California coast. Volume I includes the report, Appendix A, and Appendix B. Volume II includes Appendix C. Volume III includes Appendix D. Volume IV includes Appendix E and Appendix F. Volume V includes Appendix G, Appendix H, and Appendix I.

Genotoxic effect of nickel chloride and zinc sulphate on fish Hypophthalmichthys molitrix

The present investigation is to assess the genotoxic potential of nickel chloride and zinc sulphate on gill cells of silver carp Hypophthalmichthys molitrix. Fishes were exposed in sublethal concentration of nickel chloride 5. 7 mg/1 and zinc sulphate 6.8 mg/1, and sampled at 10, 20 and 30 days. Nickel chloride and zinc sulphate treated fishes exhibited an apparent increase in the aberration frequency and a decrease in the mitotic index as compared to control. Acentric fragment, chromatid break, endoreduplication, chromatid gap, centromeric fusion, ploidy, sticky plate, dicentric chromosome, clumping and partial sticky plates were some of the abnormalities observed. The chromosomal aberrations in the treated fishes were significant compared to control.

Dynamics of parasite population and its histopathological and histophysiological effects in the stomach of a freshwater fish

The caryophyllaeid cestode Lytocestoides fossilis infects the freshwater catfish Heteropneustes fossilis. The study was conducted for two consecutive years (2004-06) to record the bio-statistical data of the parasite. The incidence, intensity, density and index of infection of the parasite have been recorded. The infection was more during June to September, moderate during February to May and low during October to January. The parasite brought about severe histopathological changes in the stomach of infected fish. The changes observed in the stomach of fish included structural damage of the villi, inflammation, and fibrosis associated with hyperplasia and metaplasia. The hypertrophy of mucous layer led to vacuolation and necrosis. Histochemical changes were noticed with enhanced carbohydrate, protein and lipid contents. The enhanced substrate content in the infected organ might be due to the disfunctioning of the digestive tract, which results in the accumulation of various metabolites. Mucus secretion was triggered as a protective interaction against parasitic invasion. The parasitic infection affects the general metabolic state of the host and as the result, the fish becomes sluggish and moribund.

Studies on the age and growth of Labeo calbasu (Hamilton) with an exploitation pattern from the Ganga River system, Uttar Pradesh (India)

Samples were collected to study the age and growth of Labeo calbasu (Hamilton) from the river Ghaghra (Guptarghat centre, Faizabad). The scales of L. calbasu have been used for age and growth studies in present paper. Study of the marginal rings on the scales of L. calbasu indicates their annual nature. The fish attained growth in 1st 18.7 cm, 2nd 27.8 cm, 3rd 35.7 cm, 4th 41.8 cm, 5th 46.9 cm, 6th 54.9 cm and 7th 57.4 cm years of the life. The growth rate was observed 18.7, 9.1, 7.9, 6.7, 5.1, 8.0 and 2.5 cm for 1st to 7th age classes respectively. The age groups 1+ to 4+ constituted 91.17% of the total exploited population and 8.83% of remaining age groups (5+ to 7+). The maximum exploited population was observed in 2+ age group with 33.68%. Overall exploitation pattern was systematic and a good indicator for heavy recruitment.

Fat and water contents of the muscle and gonad of Otolithus argenteus in relation to gonad growth

Fat and water contents of the muscles and gonads in relation to gonad growth in Otolithus argentes from Karwar are reported. Water content showed an inverse relationship to lipid in both the sexes. Variation in somatic body weight was found associated with the fluctuations in lipid contents.

Spiny lobsters and their fishing techniques

Scores of publications on spiny lobsters and their fishing techniques are available from various parts of the world. A variety of fishing gears which vary in design and operation are employed for exploiting lobsters. A review of the work carried out on spiny lobsters with special reference to their distribution, fishing gear, fishing methods, baits and crafts in India, Sri Lanka, United States, Australia, South Africa, United Kingdom, Ireland and Portugal based on selected literature are considered and discussed.

Development of lobster traps: preliminary experiments with three new designs of rectangular, Australian pot and ink-well traps

Result of experimental lobster fishing with three new designs, namely rectangular, Australian pot and ink-well traps at Muttam, Kadiapatnam, Colachal, Enayam and Vizhinjam, south-west coast of India during 1979-80 are reported. Preliminary studies show that Australian pot and rectangular traps as more efficient to the ink-well type.

On the arrival time, waiting time to unload, unloading time and waiting time for departure for purse seiners at Mangalore landing centre

Fifty four purse-seine boats at Mangalore landing centre were observed during different stages of unloading fish catch. It was found that a boat takes 75% of the berthing time to unload an average quantity of 2.4 tons of fish. Further, unloading period and catch were found to be directly related where it was estimated that 5 to 7 minutes are spent in unloading about half a ton of fish to a nearby tempo by employing 9 ± 2 laborers.