Seasonal variability in penaeid prawn larval abundance in the Mandovi and Zuari estuaries, Goa

Seasonal variations in the occurrence and abundance of penaeid prawn larvae in the Mandovi and Zuari estuaries of Goa were studied. Larvae and post-larvae of commercially important species viz. Metapenaeus dobsoni (Miers), M.affinis (H. Milne Edwards). M. Monoceros (Fabricius), Penaeus merguiensis de Man and Parapenaeopsis stylifera (H. Milne Edwards) were recorded in that order of abundance. Protozoea and mysis stages were dominant in surface zooplankton collections while the post-larvae were more in the bottom samples. Based on larval density, M. dobsoni appeared to be a continuous breeder. The active spawning periods in other species were during the late post-monsoon and pre-monsoon seasons varying with the species. Peak recruitment of post-larvae in the estuaries was observed mostly during southwest monsoon months (June to September). Penaeid prawn larval ingression was more in the Zuari estuary compared to the Mandovi estuary. Their numerical abundance gradually decreased towards the upstream areas. The feasibility of large scale collection of penaeid prawn larvae for aquaculture is indicated.

A new record of two penaeid species from Goa coast

Adults of Penaeus japonicus (Bate) and juveniles of P. canaliculatus (Olivier) were recorded for the first time from the coastal and estuarine regions of Goa respectively. Their presence in Goa waters suggests that both the species have a wide distribution along the west coast of India. The available data from the neighboring states suggest that both the species are distributed in deeper waters and are caught during or immediately after the southwest monsoon. Hence, it may be possible to tap these valuable resources from Goa waters if the fishing operation is extended to depths beyond those presently fished and fishing is carried out during the SW monsoon season.

Performance of paddy-cum-prawn culture in rainfed low land ecosystem of Sunderbans

Performance of both paddy (Var. NC 492) and prawn Penaeus monodon were assessed for two years during wet-season in rainfed lowland ecosystem with a view to study the economic viability of paddy-cum-prawn culture in the coastal saline zone of West Bengal. Both mono and dual culture of paddy and prawn were tried in the study. Fingerlings of prawn (α 35,000 haˉ¹) of 10-15 mm size were reared for about three and half months with and without fish feed. It was observed that addition of fish feed resulted in higher (57.7%) production of prawn (2.65 mg/haˉ¹) but not rice. Such increase in prawn production was 1.6 times higher when no feed was provided and 1.4 times higher when grown as sole crop. However, paddy, whether grown as mono or mixed culture, did not differ in yield significantly. In dual culture, the benefit - cost ratio was higher (6.83) when prawn was grown with feed and it was maximum (36.0) when grown without feed as sole crop. The study, therefore, indicates that paddy-cum-prawn culture under low land ecosystem of the coastal saline zone is enterprising particularly for small and marginal farmers who fear to take risk of growing prawn alone at the cost of paddy.

A record production from an integrated farming system utilising sewage enriched water

The results of experiments conducted on a pond dyke (655m²) in the Wastewater Aquaculture Division of the Central Institute of Freshwater Aquaculture, Rahara, during 1992-93 for maximising production through optimum utilisation of resources are communicated. Round the year intensive cultivation of okra (Abelmoschus esculentus), amaranth (Amaranthus gangeticus and A. viridus), water-bind weed (Ipomea aquatica), Indian spinach (Basella rubra), radish (Raphanus sativum), amaranth (Amaranthus viridis), cauliflower (Brassica oleracia var. votrytis), cabbage (Brassica oleracia var. capitota) and papaya (Carica papaya) was undertaken using the treated sewage water from fish ponds for irrigation. The pond dyke yielded 5,626.5 kg vegetable which worked out to 85.9 tons per ha per year. Multiple cropping with these vegetables excluding papaya on a 460 m² dyke recorded a production of 4,926.5 kg at the rate of 107.1t per ha/yr. An improved yearly net return of about 35% over investment could be achieved through the selection of highly productive and pest resistant vegetable crops of longer duration for integration into the system. Introduction of this type of integrated farming would enhance the overall productivity and returns from farming.

State of the stocks of shallow water prawns at Sofala Bank

In 1977 a preliminary assessment of the shallow water prawn (Penaeus indicus ) stocks at Sofala Bank (Mozambique) was made (Ulltang et al., 1980). Using additional data from 1977-1982, the first assessment was updated in 1980 (Ulltang, 1980) and in 1983 (Ulltang et al., 1983). The present report includes a detailed description of data and explanations of the methods used in the last assessment. Data from 1983, which were not available during the last assessment, are also included.

Relatorio do cruzeiro realizado no Banco de Sofala pelo arrastao Muleve em Julho-Agosto/1979

In July-August 1979 a first survey of Sofala Bank was carried out with shallow water prawn resources as the main objective. Some preliminary conclusions on the circulation in the Sofala Bank and the influence of the Zambezi River in this area were drawn. Analysis of catch rates and distribution of the different prawn species resulted in the division of Sofala Bank in 6 areas. Particular importance is given to the species Penaeus indicus and Metapenaeus monoceros which constitute 70-90% of catches in depths less than 25 m. The greatest concentrations of P. indicus are found very close to the shore, principally in an area north of Quelimane and another south of Angoche. At the time of the survey 40% of females of this species were in late maturing stages. The species M. monoceros is most abundant in depths greater than 15 m, with concentrations south of Zambezi River and in small areas near Pebane and Angoche.

Distribuçāo e biologia das espécies de camarāo de águas pouco profundas

This study investigates the life cycle of the two major commercial species of prawns in Mozambique - Penaeus indicus and Metapenaeus monoceros - and their prime nursery microhabitats in the mangrove swamps.

Alternativas de gestāo da pescaria de camarāo de águas pouco profundas

The shallow-water shrimps represent the most economical resource in Mozambique. Therefore, annual surveys have been carried out to investigate the state of the stock, the fishing methods for a better analyses catch/effort statistics. Resource assessment was conducted on principal species - Metapenaeus monoceros and Penaeus indicus - to estimate levels of abundance and distribution in the Sofala Bank.

Análise dos efeitos da introduçāo de medidas de gestāo na pescaria de camarāo do Banco de Sofala

Biological effects of management measures introduced in the shrimp fishery from 1985 to 1990 are analysed as well as the results from simulation of different closed seasons. Observed changes in recruitment, total catch, biomass and average individual weight during 1985 to 1990 for Penaeus indicus and Hetapenaeus Monoceros are also analysed. Further studies on a stock-recruitment relationship are important due to decline of recruitment levels in this period. A three-month closed season starting in January is recommended, without increases in the monthly fishing effort. The TAC shall be fixed according to the recruitment level each year.

Relatório do cruzeiro realizado no Banco de Sofala pelo navio "Pantikapey" de 7/23 - Junho de 1981: camarāo de superficíe

This report of the cruise along the Sofala Bank (Mozambique) describes the catch composition and catch distributions of the shallow water shrimp. Biological data are given for Penaeus indicus and Metapenaeus monoceros which represent 77% of the total catch.

A report on a survey with the r/v "Ernst Haeckel" in July-August 1980: shallow-water shrimp and by-catch, oceanography

A survey of the Sofala Bank (Mozambique) was conducted to: estimate the abundance of shallow-water shrimp in the area between 16 degree 20'S and 20 degree 20'S, from 5 to 100 meters; estimate the shallow-water shrimp species composition and distribution pattern of main species. Collect biological data of the main species, Penaeus indicus and Metapenaeus monoceros; study the shrimp by-catch, species composition and biological data collection of the most abundant species of commercial value; and collect environmental data to clarify the shelf circulation on the Sofala Bank and the main oceanic features in the regions 15 degree S to 18 degree S and south of 22 degree S.

Relatório do cruzeiro realizado no Banco de Sofala no barco "Meleia" em Agosto de 1981: camarāo de águas pouco profundas

The geographic and bathymetric distribution of the shrimps Penaeus indicus, Metapenaeus monoceros, P. japonicus and P. monodon along the coast of Mozambique are given. Biological data of the main species P. indicus and M. monoceros are presented.

Camparaçāo entre os cruzeiros de investigaçāo realizados no Banco de Sofala pelo navio SRTM "Sebastopolsky rybak" em Setembro-Outubro e Novembro-Dezembro de 1982: camarao de [águas pouco profundas]

During the last 4 months of 1982, two research cruises had been carried out at the Sofala Bank by the SRTM "Sevastopolsky Rybak". The authors analyze and compare data on biological characteristics, sexual maturity and localization of Penaeus indicus and Metapenaeus monoceros.

Relatório do cruzeiro realizado no Banco de Sofala pelo navio SRTM "Sebastopolsky rybak" de Novembro a Dezembro de 1982: camarāo de águas pouco profundas

From November 18th to December 17th 1982, the SRTM "Sebastopolsky Rybak" carried out research cruises on the Sofala Bank in the area between 16°20'S and parallel 19°40'S. The authors analyze data collected on biological characteristics, sexual maturity and localization of Penaeus indicus, Metapenaeus monoceros, Penaeus japonicus, Penaeus monodon and Penaeus latisulcatus.

Water quality parameters of coastal shrimp farms from southwest and southeast regions of Bangladesh

The impacts of shrimp farming on water quality and effluent loading of shrimp farms in southwest (Khulna) and southeast (Cox's Bazar) regions of Bangladesh was investigated during March-August and August-October season, respectively. Water salinity fluctuated from 3.0 to 15.0 ppt in the southwest, whereas it was between 2.5 to 20.0 ppt. in southeast region. Total ammonia nitrogen as recorded in most farms of Cox's Bazar region was higher (0. 1160.438 mg/L) than the recommended level of shrimp farming. Mean values of total ammonia nitrogen and total nitrogen at the outlet of shrimp farms were higher than those of inlet in both regions. Mean values of phosphate phosphorus and total phosphorus at outlet were lower than inlet except in harvest time of Penaeus monodon. Total suspended solids were deposited on the bottom of shrimp farms in both regions, which resulted in higher concentration in inlets than outlets in both regions.