Prawn fishing by M.F.V. Jheenga in Bombay waters

The design and construction of the motor fishing vessel Jheenga of the Deep Sea Fishing Station of the Government of India, Bombay, the areas covered and the gear used by her in 1959-63 are described. The prawn catches in relation to the total catches, and their catch rates in different months in area 18-72 in Bombay region which was fished continuously during the five years period have been studied with a view to ascertaining their seasonal abundance. The results indicate the availability of the prawns in the region for the major part of the year from March to October-November. High catches with high catch rates forming high percentage of their abundance in total catches are obtained in July to October.

Trends in development in the prawn fishing technique in India: a review

The paper provides some background information about the developments in the prawn fishing technique. The important indigenous gear for prawns are the filtering type nets like the stake nets, boat seines and beach seines with bag. The only indigenous net, which can be compared in design with the modern bottom trawling gear, is the "Thuri Valai" of the Madras Coast. Prawns have also been reported from the catches of gill nets and cast nets. Dredges and beam trawls are simplest among the dragged gear. Even though several earlier attempts were made with the beam trawl, in 1959 season a detailed experiment was made to study the fishing features of this gear. The subsequent experiments conducted were for comparison with otter trawl, towing of 2 beam trawls one behind the other and the use of tickler chain. The initial experiments with otter trawls were mainly directed towards operational aspects. The experiments were to evaluate the effectiveness of fully mechanised and partially mechanised operation, the effect of extra buoyancy of floats and the use of tickler chain. Subsequent developments had been on the structure and design of prawn trawling gear. Effect of long wings and sweeps were tested. Catches of nylon and cotton nets were compared. The sizes of meshes of the cod-end have also been increased.

A survey of the microbiological quality of commercial frozen prawn products

The paper presents the results of a bacteriological survey carried out on 2,917 samples of frozen prawn, 55 samples of raw material, 35 samples of water, 4 samples of ice and 42 samples of various equipment used for processing. The survey covered a period of three years (1960-63) and comprised of samples collected from five of the leading processing factories in Cochin. Frozen products tested consisted of headless (marine and fresh water), peeled and deveined and cooked frozen samples. Statistical analysis of the data shows that there is no significant variation between samples and between factories with respect to product quality. The standard plate count varied between 1.0x10(4 superscript) and 1.0x10(6 superscript) per gram for headless and between 1.0x10(4 superscript) and 1.0x10(7 superscript) for peeled and deveined and cooked frozen samples. Majority of the samples had bacterial load well within the limits prescribed for such products.

Investigation on sanitational aspects (microbiological) of prawn processing factories

Absence of regular cleaning has been found to result in heavy bacterial loads on the surfaces of utensils and other equipment used in prawn processing factories and peeling centers. Instance of high faecal contamination is also sometimes met with. Detailed investigations have shown that a cleaning schedule comprising of treatment of these surface with a detergent followed by application of an effective disinfectant like sodium hypochlorite would prevent such bacterial build up.

Preliminary studies on blanching of prawn

The paper represents results on the studies undertaken to find out the causes of irregular drained weight conditions in commercial canned prawn samples. The tendency of cooked prawn to attain the equilibrium moisture content (72-74% in M. affinis and M. dobsoni) when in contact with brine has been found to be mainly responsible for the loss and gaine in drained weight. Underblanching results in loss of moistures from the meat during processing. It has been found that under standard blanching conditions, which is independent of initial moisture content, salt concentration of the blanch liquor and the temperature of sterilisation, the fluctuation in the drained weight could be avoided.

Cholesterol from prawn-head waste

A process is described for the isolation of Cholesterol from the fat obtained from prawn head-waste. Cholesterol of about 94% percent purity is obtained. The final yield on the basis of fat is about 2%.

Occurrence of a deeper red colour in prawn pulp prepared from iced-prawns

In commerce, great importance is given to the color of the dry prawn pulp in its quality evaluation. The possible correlation between this color factor to the iced or not iced condition of the raw prawn used, is investigated. The study reveals that as the icing period of the raw material increases the color of the finished product proportionately intensifies to a bright red compared to light brownish yellow or orange color of the product from the not iced prawn, and at the same time the other characteristics like flavor and taste deteriorates as the time of icing advances. This finding tends to show that the color factor does not reflect the true quality of prawn pulp. Based on chemical data it is suggested that "browning" due to Maillard reaction may have an important role in this color phenomena.

A study on the quality of prawns during processing in prawn-freezing factories

A study on the occurrence of defective pieces of prawns at three different stages of processing of headless shell on and peeled and deveined varieties was undertaken, each in one freezing factory. The average percentages of the defective prawns together with the standard deviation observed over a period of one year at the three stages are mentioned. Correlation is indicated between the occurrence of the defective pieces at the pre-freezing stage and those of earlier stages.

Experiments in constituting a taste panel for canned and frozen prawn products

With a view to constituting a taste panel in the laboratory for detecting the flavor changes in canned and frozen prawn, three methods of panel selection (scalar scoring method, range and deviation method and triangular method) were tried. Out of the three, triangular method was found to be suitable for panel formation in canned and frozen prawn. Using this method a panel of six members was formed for detecting flavor changes in the two products.

Factors controlling drained weight in canned prawn

The paper gives an account of factors controlling the drained weight in canned prawn. The most important among them are concentration of brine used for blanching and blanching time which are found to be fixed and specific for different sizes of prawn irrespective of the quality of the material used. Other factors such as, acidity of brine used for filling the can, volume of brine, time of sterilization and time of cooling the blanched meat are also to some extent found responsible for fluctuations in drained weight.

Seasonal fluctuation in the distribution of eggs and larvae of flat fishes (Pleuronectiformes - Pisces) in the Cochin backwater

Attempts have been made to correlate the abundance of eggs and larvae of flat fishes belonging to families Cynoglossidae and Soleidae with the hydrographical parameters of the environment, particularly the salinity. The eggs and larvae were found to occur in the Cochin backwater during the pre-monsoon period but not during the south west monsoon period. During the south west monsoon period larvae belonging to very early stages were found at the marine end (Fairway Buoy). The continued or prolonged existence of very low salinity appears to restrict the distribution of flat fish larvae. In the post-monsoon period also the eggs and larvae were not found in regions of very low salinity. Larvae of Cynoglossus puncticeps (Richardson), C. brevis Gunther, C. cynoglossus (Ham. Buch), C. lida (Bleeker) and Solea heinii Steindachner were obtained in the collection taken from the estuary. From the data it is seen that each species has specific spawning period.

A study on damage caused to crustacean and finfish larvae during collection of Penaeus monodon (Fab.) postlarvae in the estuaries of Barguna, Bangladesh

A year round investigation in the estuaries of Barguna district revealed that for each Penaeus monodon postlarvae (PL), about 37 larvae of other shrimp species, 12 finfishes and 10 macrozooplankters are destroyed during the process of shrimp seed collection. Although abundance of P. monodon PL was not recorded throughout the year, a significant number of other shrimp spp., fin fishes including macrozooplankters are being damaged by the shrimp seed collectors. This indiscriminate destruction of aquatic organisms during P. monodon PL collection is serious threat to aquatic biodiversity.

Rearing of Clarias batrachus (Lin.) larvae with formulated diets

An experiment was carried out for a period of 20 days using 7-day old Clarias batrachus larvae of initial total length of 7.4 ± 0.49 mm and weight of 2.9 ± 0.83 mg. Three artificial diets were used for the study having three replication of each. Among these, diet-I was formulated using 20% fish meal (FM), 30% powdered milk and 30% boiled egg yolk (BEY), diet-II using 27% FM, 20% Baker’s yeast (BY), 30% BEY and 3% agar and diet-III using 20% FM, 20% BY and 45% whole egg. The larvae fed on diets-II and III showed significantly (P<0.05) better length and weight gain than those of the larvae fed on diet-I. The larvae fed on diet- III showed the best survival rate (70%). However, the condition factor of the larvae fed on diet I was significantly better than those of the larvae fed on other two diets. The results of the study showed that C. batrachus larvae could be successfully reared with diet containing 45% whole egg, 20% yeast and 20% fish meal.

Rearing of catfish (Clarias batrachus Lin.) larvae with live and prepared feeds

Provision or live feed (Tubificid worms) attributed significantly better weight gain in the five days old Clarias batrachus larvae when reared for another 28 days compared to those fed mixed feed (live and artificial) and artificial feed only. Larvae fed mixed feed showed significantly better weight gain compared to those fed only artificial feed and the survival rate was similar to those fed only live feed. Both the weight gain and survival rate were the lowest for the larvae reared only on artificial feed.