Life history of prawns: a review of recent studies with special reference to Indian species

The paper contains a brief review of the studies on the life histories of Indian species of prawns chiefly belonging to the family Penaeidae. References to similar work carried out outside India are furnished where significant variations have been observed. The three main larval stages viz., Nauplius, Protozoea and Zoea (Mysis) and their important characteristics, including modes of locomotion, are described. The post-larval development of one species that has been studied in detail (Metapenaeus dobsoni) is indicated in outline. Some aspects of the bionomics of these prawns, especially breeding and migration, are also briefly dealt with in view of their relevance in their life cycle. An outline of the life histories of some Palaemonid prawns of both fresh water and marine habitats is added at the end and the need for well- planned investigations in regard to species of such economic value as Palaemon carcinus (Macrobrachium rosenbergii) is indicated.

Biodiversity in floodplains with special reference to artificial stocking

A five years investigation on fish biodiversity in connection with artificial stocking was conducted in three south-western floodplains of Bangladesh from 1992 to 1996. The ten top most available and ten rarest fish species were identified. Puntius sp., Channa punctatus, Mystus sp., Anabus testudinius, Ambasis sp., Colisha sp. and Macrobrachium sp. etc. were the most common available species. On the other hand, Mystus aor, Notopterus chitala, Clupisoma garua, Aplocheilus panchax, Ctenophmyngodon idella etc. were the rarest species. However, the most abundant and the rarest fish species behaved differently in different floodplains in different years. Shannon diversity index was used to assess the extent of diversity in different years. The study revealed that the artificial stocking programme, to some extent, influenced the biodiversity in floodplains.

The riverine fisheries of large sized siluroids with special reference to Aorichthys seenghala (Sykes)

The significance of large siluroids in dynamics of riverine fish catch composition pinpointed the need to appraise that i) fisheries; ii) status in riverine fisheries; and iii) factors influencing their fisheries with special reference to Aorichthys seenghala (Sykes). The investigations were carried out in the middle stretch of Ganga river system around Allahabad. The study concluded that although, catch of large siluroids had declined but their share in riverine catch increased. The same was true for A. seenghala. The increase in fishing intensity in A. seenghala breeding grounds was one of the evident indicators of fishing stress on the fish. Strong seasonality was observed in its catch over the year. The wanton killing of breeding population during premonsoon and juveniles during postmonsoon may be attributed for this seasonality and decline in its catch. The fishing stress needs to be diverted through some more lucrative option to save its fisheries. Collection of young ones from the nest, during breeding months and their subsequent culture may be one of the conservation measures. It would also generate additional employment for fishers and defer wanton killing of brood stock.

Standardization of polyphosphate treatment for tiny prawns (Parapenaeopsis stylifera) with special reference to its rehydration capacity and organoleptic quality

In the present study, an attempt was made to explore the benefits of polyphosphate for enhancement of dried prawn (Parapenaeopsis stylifera) quality commercially known as "sode" in Maharashtra coast. Dip treatment in polyphosphate solution at different concentrations (viz., 3, 5, 7 and 10%) was given to pealed and no deveined P. stylifera for different durations (viz., 1, 2, 3, 4 and 5 min). Treated prawns were dried and subjected to rehydration capacity test and organoleptic evaluation. Among the different treatments, rehydration capacity was found to increase with the increased duration and concentration of treatment. Tiny prawns treated with sodium tripolyphosphate solution at the rate of 5% concentration for 5 minutes showed an increase in pH from acidic to alkaline, and had better quality with respect to rehydration capacity and textural attributes as compared to other concentrations and durations of polyphosphate treatment.

A brief report on a survey of the fish and fisheries of the Tana river, with special reference to the probable effects of the proposed barrages

The construction of several barrages in order to develop the hydroelectric and irrigation potential of the Tana river has been proposed and the probable effects of these developments upon the fish and fisheries of the area' has been investigated. Briefly in the highest reaches the sport fishery will be unaffected, in the middle reaches the sparse subsistence fisheries will be only slightly inconvenienced but in the terminal reaches of the river the subsistence and commercial fishing enterprises are expected to be seriously reduced by the progressive re-regulation of river-flow. However each new dam will support a new and productive reservoir fishery and with proper development the annual yield of fish from the Tana basin is expected to increase considerably.

Demersal fishery resources of Sri Lanka and its present level of exploitation with special reference to off-shore and deep-sea waters

Following a brief review of development of demersal fishing off Sri Lanka, the author reviews the fishing grounds of the Wadge Bank, the Pedro Bank, and the Mannar Bank. He reviews the deepwater trawling fisheries particularly in relation to the 1972 survey conducted by the 'Optimist' and also small boat trawling in coastal waters. Lastly he considers handlining for groundfish, which is principally conducted by fishermen operating traditional craft.

Pelagic fishery resources of Sri Lanka and its present level of exploitation with special reference to off-shore and deep-sea waters

Pelagic resources around Sri Lanka may be categorized into three major groups: (1) the small pelagic varieties such as the sprats, halmessa, sardines (salaya, soodaya), and herrings (hurulla). (2) the medium size pelagic species such as the mackerel (kumbala and bolla), barracuda (jeela), seer Spanish mackerel (thora), frigate mackeral (alagoduwa), mackerel tuna (atawalla) and the skipjack (balaya). (3) the large size fishes such as yellow fin tuna (kelawalla), big eye tuna, marlins (koppora and gappara), sail fish (thalapath), sharks (mora) and rays (maduwa). Production levels of exploited resources are noted, and seasonal patterns and annual in their abundance are considered. On the basis of observations and estimations of the existing fisheries, and the results of experimental fishing, figures are presented of the potential yield of those species already exploited. The development of that potential depends on the development of modern techniques of pole and line fishing, application of tuna longline and shark longline, increasing the number of units of drift nets and the introduction of a bait fishery for the longline and pole line fishery. Some features upon which the successes of any venture to exploit such resources are noted, particularly those which relate to the nature of the fishing vessels used.

Processing and marketing of fish with special reference to export of pelagic fish and fish products

The paper describes the world tuna fishery, industry and markets and the trends for its future development. The prospects for developing a tuna export industry in Sri Lanka are discussed. Suggestions are given as to products composition, international co-operation and utilization of available processing facilities. The need for industry and export support is stressed, and it is concluded that preparations for the development should start well in time.

Remote sensing of the oceans from space with special reference to marine resources

A number of ocean science fields have profitted, either directly or indirectly from satellite remote sensing, including physical, biological and geological oceanography. User oriented applications include fishing, shipping, offshore drilling and mining, coastal engineering and coastal hydrology. Following a brief account of the technology involved, areas in oceanography benefitting from satellite information are detailed. Examples are given of satellite data applications to marine resources.

Evaluation of biochemical characteristics of a traditional salt fermented fish product of northeast India with special reference to its flavour components

'Lona ilish', is a traditional salt fermented fish product, widely consumed and very popular in north-east part of India and Bangladesh. It is prepared exclusively from a high fat fish, Hilsa (Tenualosa) ilisha. 'Lona ilish' was prepared in the laboratory following traditional process. After 150 days of fermentation, a better quality 'lona ilish' was obtained. Biochemical characteristics of market sample was estimated and compared with the laboratory prepared one. A variation in biochemical composition was observed. Sensory quality of the final product of laboratory prepared 'lona ilish' was compared with the market sample and found that the laboratory prepared product scored better than the market sample. The moisture (49.89%) and salt (15.48%) of the final product was found to be satisfactory for stability of the 'lona ilish' at ambient temperature. Analysis of volatile compounds of 'lona ilish' was done using GC-MS. It was concluded that, aldehydes, ketones and esters may possibly contribute characteristic aromas to the overall flavour of the salt fermented hilsa.

A record of Probopyrus bithynis (Richardson, 1904) in Macrobrachium rosenbergii (De Man) from coastal Andhra Pradesh, India, with special reference to host-parasite relationship

An incidence of bopyrid isopod infestation was observed in giant freshwater prawn, Macrobrachium rosenbergii (de Man) juveniles (40-60 mm/0.9-1.5 g) in a scampi culture farm in East Godavari district of Andhra Pradesh. The presence of parasite was observed by conspicuous boil like swelling of the branchial chamber where the parasite was found lodged on the gills. The infested gill was highly compressed and necrosed. Only one branchial chamber was infested by the parasite while the other gill was normal. The infested prawns were thin and emaciated and showed retarded growth. The parasite was identified as Probopyrus bithynis (Richardson, 1904) which caused inhibition of ventilation due to its permanent lodging in the branchial chamber and impaired the gaseous exchange by gills. It was also observed that this parasite caused parasitic castration in the infested prawns.