Studies on the status of pollution in certain estuarine areas in Kakinada

The BOD levels and saprotrophication of 2 stations in an estuarine habitat at Kakinada India, was studied during one full tidal cycle. Both the stations were found to be heavily polluted by sewage with BOD values ranging between 10.8 and 12.8 ppm at the commercial canal (station 1) and between 4.8 and 8.8 ppm at the mangrove creek (station 2). Tides did not seem to have much influence on the dilution of the pollutants. Based on planktonic indicator species observed and saprobity index which worked out to be 2.75, both the sampling areas are considered as heavily polluted alpha-mesosaprobic zones.

Management of waterlogged areas, island and coastal saline soils using fish based mixed farming system

Problems in India regarding the management of various coastal saline soil and waterlogged environments are discussed in detail, considering in particular the potential application of mixed fish farming systems. Various operational and cost requirements of such systems are examined.

Nature of the rain spectrum at a low latitude coastal station

The internal structure of rain falls in terms of rain rate during various instances of time can be determined by measuring rain amounts received during very short intervals of time. A system that can record the intensity of rain fall at every minute has been used for this study.

Deepwater prawns and lobsters off the Kerala coast

Majority of the prawn catch of the Kerala coast comes from the inshore regions within the 10 fathom line. A bottom deposit formed of fine mud rich in humus is found to be the ideal condition for the penaeid prawns. Similarly the lobster is observed in large numbers at localised areas very near the coast in the crevices of rocks. Though it has been observed that prawns and lobsters exist in deep water as well under different conditions, our knowledge about these forms along the Indian coasts is very scanty, being restricted to the works of Spence Bate, Alcock, De Man and Ramadan. Recently, during the cruises of the University Research Vessel Conch off the Kerala Coast (1958-1963) two species of deep water prawns and one species of lobster were collected from depths 100 - 180 fathoms. Of these, Penaeopsis philippi is found in large numbers occupying an almost continuous bed extending from Anjengo to Mangalore, while P. rectacutus has a restricted appearance between Cochin and Calicut. However, some sort of year to year variation has also been observed regarding the abundance of the species at various stations. Peurulus sewelli has a more restricted distribution, the maximum number being found between Puvar and Cochin. Attempt has been made to correlate the occurrence of the species with the hydrological conditions at the bottom and the nature of the substratum. It is observed that Peurulus sewelli occupies a more or less hard bed formed of sand with shell fragments or stones and small percentage of silt, the bottom temperature at the stations varying from 11°C to l4°C. P. sewelli is a more or less permanent inhabitant of the edge of the continental shell off the Kerala Coast worthy of attention for detailed investigation with a view to explore the possibilities of commercial exploitation.

Limnology of Chanda beel

A limno-biological investigation was conducted in Chanda beel over a period of 8 months from June ‘95 to January ‘96. The floodplain showed temporal spatial and vertical variation in physico-chemical as well as biological conditions. During study period, physico-chemical parameters were within the suitable range for fish culture. Plankton population was higher in true beel areas. Both phytoplankton and zooplankton showed direct relationship among themselves. Presence of several indication plankton genera showed that the floodplain was eutrophic in nature.

A case study on the impact of industrial effluent disposal on the fishery of Amba River estuary, Maharashtra

The impact of waste discharge on fishery resources is a matter of great concern. The accepted norm in all environmental impact assessment studies is to avoid areas of high fishery potential while locating a marine outfall. Contemplating on this aspect a case study was conducted in the Amba River estuary before and after the establishment of a petrochemical complex at Nagothane. The treated wastewater from this complex is released through a subsurface outfall after adopting effective control measures for marine disposal of waste. Experimental trawling was done at five locations covering a distance of 30 km during 1990 to 1991. The catch rate within the estuary varied from 0.6 to 255 kg/h (av 24 kg/h). The trend indicated considerable decrease in fishery potential from the mouth of the estuary (av 64 kg/h) to the upstream location (av 11 kg/h). A total of 49 species of fishes, 16 species of prawns, 7 species of crabs and 1 species of lobster were identified from the collections. Number of species gradually increased from the interior segment at Dharamtar (8) to the outer area near Revas (18). A comparison of the quantitative and qualitative nature of the post outfall and pre outfall data revealed only marginal difference. The study indicates that if necessary precautions are taken to render the waste harmless the marine ecology will hardly be affected.

Brackish-water fishery resources

Ceylon has about 300,000 acres of coastal brackish-water areas of which about 100,000 acres constitute shallow lagoons, tidal flats, mangrove swamps and saline marshes, and the rest deeper lagoons and estuaries. While the former represent a vast potential resource with regard to fish farming, the latter are the sites of important fisheries. W. H. Schuster (1951) estimated the average natural production of Ceylon’s brackish waters to be less than 20 lbs. per acre per annum. Since then estimates have been made by the author for a rich lagoon, the Negombo lagoon, a poorly productive lagoon, the Ratgama lake (Dodanduwa) and studies are in progress of some of the other lagoons. The natural production of the Ratgama lake was estimated in 1959 to be 18.5 lbs. per acre per annum while that of Negombo lagoon was estimated in 1960 to be 65 lbs. per acre per annum. It is reasonable to estimate the average production of Ceylon's brackish-waters to be 25 lbs. per acre per annum. Thus the total production is about 3,350 tons per annum. Considering the fact that the island's present total production is 90,000 tons per annum, the brackish-waters contribute 3.7% of it. Schuster (1951) further states that the natural production in the brackish-waters of other countries is around 80 lbs. per acre per annum. In order to increase our average natural production to this value it would seem necessary to consider the nature, biology and fish resources of the brackish-waters and draw some conclusions with regard to their proper exploitation.

Wadge Bank trawl fishery studies. Pt. 3. Nature and composition of the resident population

The demersal stock of the Wadge Bank is known to be made up of two major groups, namely the resident and migrant stocks (Sivalingam 1966b). It is necessary to analyse the two groups separately in order to correctly interpret the changes in relative abundance of the demersal fish stocks of the Bank. The object of this paper is to present the nature of the resident stock and discuss its changes in composition from 1945 to 1960. That of the migrant population will be presented later. The significance of this analysis has been discussed earlier (Sivalingam 1966a).

A preliminary report on Chanos fry surveys carried out in the brackish water areas of Mannar, Puttalam and Negombo

This paper records the results of the Chanos fry surveys carried out in Mannar, Puttalam and Negombo lagoon areas since 1967, and gives a summary of the earlier surveys. The maximum amount of Chanos fry was obtained from Mannar area during April and May. All three areas have their main commercial fry season in April and May with a second commercially negligible season in October–November. The quantity of fry collected has been utilized to evaluate the potential fry production figures. Mannar 400,000,000 fry/annum. Puttalam 200,000,000 fry/annum. It would be extremely difficult to estimate the number of eggs laid, the larvae hatched and the fry available each year along the coastal areas of Ceylon. It is necessary to obtain biological, meteorological and oceanographical data so as to provide a basis for the prediction and estimation of fry populations in the coastal waters of Ceylon. The suggested ideal season for commercial catches of Chanos fry is April–May with operations to be carried out simultaneously all along the west coast.

Marine protected areas and small-scale fisheries in South Africa: promoting governance, participation, equity and benefit sharing

This monograph studies the progress achieved by conservation partners in South Africa on the implementation of the Convention on Biological Diversity (CBD) Programme Element Two components of governance, participation, equity and benefit sharing, from the perspective of small-scale fishing communities. It explores the strategies and mechanisms used by different authorities to create the conditions whereby local communities can benefit from marine protected areas (MPAs), of which South Africa has gazetted 24, highlighting examples of best practice. The monograph will be useful for researchers, scientists, fishworker organizations, environmentalists and anyone interested in the protection of marine biodiversity and the promotion of sustainable fisheries management.