Enteropathogenic E. coli and other coliforms in marine fish

One hundred and twenty six samples of marine fish (96 from landing centre and 30 from retail market) and swabs from deck surfaces of 34 fishing boats were examined for coliforms including enteropathogenic E. Coli. Forty out of 96 fish samples from landing centre, 24 out of 30 from retail market and 11 out of 34 fishing boats revealed coliforms. On further tests, 5, 7 and 4 coliform isolates from the three groups respectively were found to be E. coli. Two of the E. coli. isolated, one from sciaenids and one from cat fish, were found to be enteropathogenic serotypes 055 and 0111. Enteropathogenic serotypes of E. coli are reported from sciaenids and cat fish for the first time in this country.

Activation mechanism of pre-phenoloxidase in lobster and shrimp

Phenoloxidase in shrimp and lobster is shown to exist in latent form which could be activated by trypsin and by an endogenous enzyme with tryptic activity. On Sephadex G-100 gel, three isoenzymes, differing in molecular weights, were isolated from naturally activated lobster shell extracts. Mechanism of activation of ptephenoloxidase involving limited proteolysis by the activating enzyme to form isoenzymes has been proposed.

Some biochemical constituents and the calorific values of different regions of the body musculature of pond murrel Channa punctatus Bloch

A study of the distribution of some chemical constituents in the musculature of Channa punctatus Bloch showed it to be fairly heterogeneous. The increase in the levels of protein, fat, ash, total carbohydrates, glycogen, RNA, DNA and cholesterol towards the posterior region of the fillet was the result of increase in the number of cells per unit weight of the sample and in the concentration of myocommata. The distribution of water in the musculature was inversely related to that of the fat. The concentration of protein appeared to be associated with the RNA level. The posterior region of the fillet exhibited more calorific value than the anterior region.

Selectivity of gill nets for Hilsa toli and Pampus argentus

Fishing conducted off Saurashtra coast during 1971-74 with 27 units of nylon gill nets using 210/2/3, 210/3/3 and 210/4/3 twines with 51, 57 and 63 mm bar mesh and 0.70, 0 60 and 0.50 hanging coefficients have helped in standardizing an optimum gear for exploitation of commercial size group of Hilsa toli and Pampus argenteus. Gill nets of 210/2/3 with 51 mm bar mesh and 0.60 hanging coefficient for Hilsa toli and 210/2/3 with 63 mm bar and 0.60 hanging coefficient for Pampus argenteus are recommended for the commercial exploitation of these two species of fishes.

Portable electronic warp load meter

A portable type warp load meter has been developed for the use in fishing trawlers. The instrument enables to monitor the warp load in fishing trawlers accurately and easily without disturbing the routine fishing operations. The instrument can be used in several other places like cranes, bollard tests for marine engines, dry docks etc. especially when the operation has to be conducted easily without disturbing the load system. The information displayed in micro ammeter in the range 0 to 1000 kg can be fed to continuous recorders for detailed analysis and permanent records.

Evolution of suitable trawl nets for medium size trawlers - 1: Comparative fishing efficiency between 32 m bulged belly, long wing and four panel trawls

Comparative studies of the efficiency of 32 m bulged belly, long wing and four panel trawls have shown that the bulged belly trawl to be superior to the other nets in catching bottom fishes and column fishes. 40% of the bottom fishes and 48% of the column fishes were caught by the bulged belly trawl. However, for prawn catch, the long wing trawl appears to be better as it landed 52% of the total prawn catch of the three nets. Bulged belly trawl was found to be next only to long wing trawl in this respect.

In situ temperature and salinity meter

Development of a portable self-contained electronic meter for on the spot determination of temperature and salinity is described. Instant and remote measurements of temperature and salinity of sea and estuarine waters in the range of 25-30°C and 30-35°C for temperature with an accuracy ± 0.05°C and 0-37‰ and 31-37‰ for salinity with an accuracy of ± 0.2‰ and ± 0.05‰ respectively are possible with the instrument. The temperature compensations of the salinity measurements are done manually with the help of temperature charts. The temperature and salinity measurements can be fed to continuous recorders.

Lipid breakdown in oil sardine (Sardinella longiceps) during frozen storage

The problem of hydrolysis of lipids and consequent accumulation of free fatty acids and development of rancidity due to oxidation of the lipids are major problems in frozen storage of oil sardine (Sardinella longiceps). The course of the phospholipid breakdown, production of free fatty acids and the changes taking place in the major unsaturated fatty acids during frozen storage are described in this paper. The rate of free fatty acid production is faster in the fish, with the higher fat content. Unlike in lean fish, the neutral lipids are found to contribute substantially to the free fatty acid production. The fatty acids most affected during storage are C sub(20:5) and C sub(22:6). The polyene indices were found to decrease during storage. These effects are more pronounced in the fish with the higher fat content.

Nutritional quality of some food fish

The proximate compositions and amino acid make-up of silver jew fish (Johnius argentatus), Indian halibut (Psettodes erumei), grey mullet (Mugil cephalus) and pearl spot (Etroplus suratensis) are reported. Calorific values of these fishes have been calculated from their proximate compositions and their amino acid make-up compared with the available data for beef and egg. From the study, pearl spot is adjudged to be the most nutritive among the fishes studied, followed by Indian halibut, grey mullet and silver jew fish.

Investigations on long distance transportation of fish. 4. A comparative study of the performance of expanded polystyrene slabs and multi-layer gunny (jute) fabric as insulants

A comparative study of the insulation efficiencies of expanded polystyrene slabs and multi-layer gunny fabric in long distance transportation of fresh iced fish was made. Used plywood boxes (second hand tea chests) were employed as containers and the experiments conducted between Kakinada and Calcutta. All the three insulants tried, namely, 25.4 mm thick expanded polystyrene slab, four and two layer gunny (jute) fabric, all sealed in 150 gauge polythene sheets, showed comparable insulation efficiencies, considering total bacterial counts, organoleptic qualities and TMA and TVN values of the transported fish as parameters.

Parallel twin-body trawl for shrimps, its design and efficiency

Comparative studies with a new 17 m parallel twin-body trawl and a 17 m bulged belly trawl conducted off Cochin during 1974-77 are reported. The parallel twin body trawl showed an increase of 28% in catch over that of bulged belly with a break up of 39.9% and 23.1 % for prawns and fishes respectively. The increase in catch is attributed to the extra wide mouth opening (26.6 %) of the parallel twin-body trawl. Parallel twin-body trawl had 8.96% lesser resistance which resulted in lower utilization of horse power.

Studies on equilibrium moisture content of canned prawn with particular reference to drained weight

Drained weight of canned prawn depends on moisture content of blanched meat and equilibrium moisture (EM) content of processed meat. The greater the difference between the two values the more is the fluctuation in drained weight. EM is a fixed value with particular reference to the species of prawn, which has been justified mathematically and by material balance of can contents before and after processing.

Pesticide induced physiological and behavioural changes in an estuarine teleost Therapon jarbua (Forsk)

Static bioassays were conducted with pesticides like PP'-DDT, Dimethoate (Rogor) and Carbaryl (Sevin) to determine the median lethal concentrations (LC sub(50)) on an estuarine teleost Therapon jarbua (Forsk). The respiration rates of fishes exposed to pesticides, as well as those of controls were determined. Respiration abnormalities were noticed in treated fishes. The metabolic rates are generally higher in treated fishes than in the controls. The behaviour of fishes exposed to LC sub(25) (96h) concentrations of pesticides is discussed. Estuarine fishes appear to be more sensitive and susceptible to pesticides than fresh water fishes. The pesticides affect the locomotory and swimming behaviour of fishes. Loss in weight of fishes exposed to LC sub(50) (96 h) concentration of pesticides was also estimated. The present report gives a comprehensive account of the toxic nature of these pesticides to fishes.

Distribution pattern of some biochemical constituents in muscle of the common cat fish, Heteropneustes fossilis (Bloch)

The quantitative distribution pattern of fat, moisture, protein and ash has been studied in the muscle of the various zones corresponding to the dorsal and ventral regions of the body of a common cat fish, H. fossilis (Bloch). The ventral part of the body showed more accumulation of fat and ash than the dorsal part, while this dorso-ventral gradation was not marked in the case of protein content. All the four constituents also showed an increase from the anterior to the posterior zones, both in the ventral as well as dorsal regions of the body. The distribution of moisture followed an almost opposite pattern, indicating an inverse relationship with fat and ash contents.