Mahim Bay: a polluted environment of Bombay

Distribution of the marine life in relation to the extent of pollution at and outside Mahim Bay was studied. A poor marine fauna at stations A and B was associated with a relatively high intensity of pollution accompanied by high BOD and nutrients and low DO levels. A distinct deterioration in the marine life and water quality along the northern part of the bay as compared to the southern part was evident. An increasing trend in the marine fauna with decreasing intensity of pollution from inside to outside the bay was noticed.

Breeding of Indian major carps and common carp in semi-arid zone of Haryana under controlled environment

Vast barren lands are lying vacant in the semi-arid zone of India, which can effectively be utilised for fish farming. Experiments conducted in semi-arid conditions at Damdama indicated that it is possible to breed Indian major carps and common carp under controlled conditions of modern carps hatchery CIFE D-80 without depending on rain.

Induced breeding, embryonic and larval development in Heteropneustes fossilis (Bloch) in the agro-climatic conditions of Maharashtra

Heteropneustes fossilis was induced bred for the first time in the agro-climatic conditions of Maharashtra, India. The embryonic development was completed within 16-18h after fertilisation. Head and tail ends were distinguishable after 3h and 11-12 somites were visible after 6-7h. The eggs started hatching after 14h of incubation. Average hatching time was 16-18h at 26 degrees C. In first day old pro-larva, notochord was deflected upwards, eyes were darkly pigmented and alimentary canal appeared. In fourth day old post-larva intestinal coiling could be seen and yolk was absorbed. Aerial respiration started by 8th day. The 10 day old post-larva was free swimming and fed voraciously attaining a length of 20 mm in 30 days.

A simple technique of controlled breeding of carps in semi-arid environment

A semi-arid environment is a major constraint for production of carp seed through hypophysation. At a water temperature above 31 degree C fishes often fail to respond to induced breeding or produce partial or full eggs with fairly less fertilization, leading to their mortality during embryonic development. Field trials with Labee rohita and Cyprinus carpio communis prove that hypophysation followed by stripping and hatching in a water medium with reduced temperature (below 31 degree C) through controlled use of ice-water and water showers can result in 50-60% fertilization of eggs and 50-72% hatching for L. rohita, and 40-90% fertilization and 49-77% hatching for C. carpio communis. Simultaneous breeding experiments of the species in normal water temperature (>31 degree C) showed negative results.

Early and better maturity in carp brood stock with control of environment and feeding

Available of carp breeders in their prim state of maturity is a major constraint in hypophysation. Experiments conducted in a fish farm at Naihati, West Bengal, for two consecutive years, 1983-84 and 1984-85, clearly prove that by manipulation of environmental parameters such as metabolites, dissolved oxygen, running water conditions, as also of stock densities and quality and quantity of feed. Catla catla, Hypophythalmichthys molitrix, Labeo rohita, Cirrhina mrigala and Ctenopharyngodon idella can be made to attain better maturity and spawning stage much earlier than normal i.e. even in summer months and the entire stock spawned during the period from March to September. Percentage of successful breeding, quantities of eggs released and fertilised in relation to the body weight of all the species, were also found to be more in comparison to the brood stock raised through the conventional methods.

Heavy metals pollution in the coastal environment of Karachi

The marine environment near Karachi, particularly the Baba channel, Chari Kundi channel and Manora channel have been found contaminated with industrial effluents discharged by Malir and Lyari rivers, since they carry a high concentration of toxic heavy metals viz. Pb, Zn, Cu and Mn emanating from the industrial area and are received and discharged by the Lyari river. Out of 60 seawater samples collected from the above mentioned areas, Pb was present in 55 samples and Zn in 58 samples. The concentration of Pb was between 0.04 and 59.2ppm and the concentration of Zn was between 0.05 and 1.9ppm. Similarly all the 60 sludge samples collected from Lyari outfall and its adjoining area have been found to contain Pb and Zn in alarmingly high concentratios, which for Pb was between 15.4 and 3209.9ppm while for Zn was between 87 and 111.3ppm. Cu and Mn were also found in all the above samples.

The marked reduction of the Indus river flow downstream from the Kotry barrage: can the mangrove ecosystems of Pakistan survive in the resulting hypersaline environment?

This report deals with the application of knowledge of mangrove ecosystems from around the world to the understanding of the present status of mangroves ecosystems in Pakistan.

Increasing farm income by introducing fish culture in deepwater rice environment

Fish culture in deep-water-rice (DWR) environment using net pen and polder systems was evaluated. In net pen rohu and Thai silver barb were cultured, whereas a 5-species combination (rohu, mrigal, common carp, grass carp and Thai silver barb) were cultured with BR3 rice variety and DWR. Boro-fish production system produced 2.8 t/ha of fish and 7.33 t/ha of rice in polder system with 5-species combinations.

Growth and production of Nile tilapia (Oreochromis niloticus Lin.) in irrigated Boro rice under floodplain environment

The experiment was conducted at BRRI Regional Station, Habiganj during 1994-95 to evaluate the growth and economic performance of Nile tilapia, Oreochromis niloticus, fish reared in the field of irrigated boro rice with different fertilizer levels. Grain yield of rice was not affected by fish culture. It was observed that 50% of recommended fertilizer was enough to produce increased rice yield (8-10 t/ha) at floodplain environment and additional yield was obtained with the increasing fertilizer rates. Results further indicated that O. niloticus could successfully be reared in the field of irrigated boro rice with recommended fertilizer level. Larger size of fingerlings at release had improved recovery percent, body weight gain and higher fish yield. Results also revealed that rice + fish production system produced higher net return than the system with rice alone.

Toxigenic molds on fish feeds-1: impact of climatic change

The present communication is a survey report carried out to assess the incidence of toxic mycoflora on seven types of agriculture products/by products incorporated during fish culture as supplementary dietary items. Samples were obtained from various sources at Darbhanga, Madhubani and Samashtipur districts during summer, winter and monsoon months. Out of the total 1774 samples, only 894 appeared to be fresh visually reflecting average incidence of contamination around 46.6%. However, the apparently fresh samples, when subjected to culture, 26.9% of them were found to be contaminated. Thus, degree of fungal spoilage in feed ingredients in parts of north Bihar appears to be significantly high (73.5%). The present study illustrates the facts with special reference to Aspergillus flavus, A. parasiticus (elaborating aflatoxins) A. ochraceous, Penicilium viradicatuin (elaborating ochratoxins) and A. versicolor (elaborating sterigmatocystin). The other strains already known for their toxigenic potentials that appeared on the present substrates included A. niger, A. fumigatus, A. candidus, P. islandicum, Rhizopus spp. and Mucur spp. Studies indicate that the prevalent climatic factors like temperature and relative humidity facilitate a congenial condition almost all through the year and in particular during summer and monsoon months. But water content of the substrates is a vital factor that further accelerates the pace of mycobial spoilage. A thorough sun-drying of the agricultural commodities before prolonged storage to bring water content below the "low risk limit" may significantly reduce the incidence of molds.