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%.

On the comparative efficiency of conventional and bulged belly fish trawls

To ensure a greater vertical opening while under tow, a trawl net with a bulged belly was made and compared with a conventional design under actual fishing conditions. It was found that the new design landed 31.8% more fish. Since the percentage lateral spread was relatively less for the bulged belly net, it was inferred that this net had higher head line height, while under operation and this was further substantiated by a greater catch of off—bottom fishes. Further, half the quantity of twine can be saved by changing the conventional trawl to that of bulged belly type.

Studies on phenolase enzymes in prawns. Pt. 1. The distribution and physical properties of phenolases in Penaeid prawns

The distribution of phenolases in certain species of Penaeid prawns has been studied. Attempts were made to locate the regions of maximum enzyme activity in the prawns. The relative dopase activity has been examined in extracts from head, tail, shell with cuticles and muscle. The head juice and tail extracts were found to register very high order of enzyme activity. Metapenaeus affinis, Metapenaeus monoceros and Penaeus indicus record comparatively higher enzyme activity than Parapenaeopsis stylifera and Metapenaeus dobsoni, no definite relationship has been found between the relative activity of the enzyme and size grade at least in one species examined. Experiments were done to determine the pH optima of the enzyme and the influence of pH on its deactivation. Exposure to higher temperatures up to 55°c was shown to activate the crude enzyme considerably. The possible implications of the observations have been discussed.

On the response of Catla catla (Ham) and Cirrhinus mrigala (Ham) to the voltage gradient of electrical field

The threshold body voltage (voltage gradient between head and tail) required for first reaction, electro-taxis and electro-narcosis depended upon species, conductivity of the fish body, nature of current and wave shape. Larger fishes showed first reaction at a lower body voltage than smaller ones. All the three reactions were dependent on the accommodation of nerves to the electrical field and subsequent fatigue of the fishes. No significant change was observed in the period of narcosis and recovery after repeated stimulation.

Effects of cowdung application on the production of mud crab (Scylla serrata Forskal) in brackishwater pond

A culture experiment of mud crab for 84 days was conducted in earthen pond at Brackishwater Station, Bangladesh Fisheries Research Institute, Paikgacha, Khulna. The aim of the experiment was to study the effects of cowdung application on crab production and water quality. There were three treatments as without cowdung (T1), 500 kg cowdung/ha/fortnight (T2) and 750 kg cowdung/ha/fortnight (T3) with three replicates for each. The result was evaluated on the basis of growth, production, survival rate etc. The experimental months were mid-April '96 to mid-July '96. To maintain a good water quality, water was exchanged in every spring tide. The range of salinity during the experiment was 8-19 ppt. Trash fish and fresh shrimp head were used as feed on raw basis in every alternate week at a rate of 8% body weight of crab at the same time rice bran and wheat flour were used at a rate of 2% body weight as a source of carbohydrate. The production of T1, T2 and T3, were 720.35 kg, 862.16 kg and 669.19 kg/ha respectively. Though the effects of cowdung on production of crab is insignificant but in terms of production, survival rate and growth, the study suggest that the application of cowdung in addition to feed can be recommended for mud crab culture at a rate of 500 kg/ha/fortnight.

Preliminary observations on the morphometric characteristics, length weight relationship, food and fedding habits and fecundity of Saurida tumbil (Bloch) off Bombay coast

Fifteen morphometric and four meristic characters of Saurida tumbil were studied and their relationships with total length and head length were established. The length weight relationship worked out to be W= -5.6055 L(super)3.291. The fish is a carnivore, feeding mainly on small fishes, molluscs and crustaceans. Larger fishes are selective feeders on fish. It is a long protracted spawner. Fecundity varied from 6008 to 17384 eggs in specimens of size group 212-420 mm. Fecundity-total length, fecundity-total weight of fish and fecundity - total weight of ovary relationships were worked out to be F=0.9414 L(super)1.6626, F=180.7069 W(super)0.7531 and F=3153.0375 W(super)0.8278 respectively.

Studies on the preparation of fish silage. 2. Rate of liquefaction in different parts of silver belly

An experiment was undertaken to determine from which part of silver belly (Leiognathus splendens) carcasses originate the autolytic enzymes responsible for liquefaction of silage. Findings show that it is important to leave head and viscera present in order to get a satisfactory liquefaction in silage prepared from silver belly using 3.5% formic acid. The storage life of silage produced from various parts of the fish carcasses is also discussed.

Studies on threshold current densities for convulsion of fish using a square wave stimulator

The threshold current densities and voltage tensions (body voltages) between the head and tail for bringing about distinct reactions in Salmo irideus, Cyprinus Carpio, Tinea tinca, Gasterosteus aculeatus and Salmo fario were studied. In C. carpio and T. tinca, absolute current densities required decreased with increase in length of fish. Threshold current densities for different reactions of fish increased with rise in water temperature and conductivity of surrounding medium except in case of T. tinca where low current densities were sufficient in higher conductivity of water. Impulse D.C. was superior to continuous D.C. Better effect was noticed in fishes in lower current densities when their bodies were parallel to the lines of current conduction.

On the reaction of marine fishes in interrupted A.C. of 50 Hz

The reactions of marine fishes in interrupted A. C. off uniform electrical field and constant current density have been studied in order to determine the optimum effective periods of shock: for narcosis and fixation. Higher effective periods were required with gradual decrease in potential difference between head and tail, which in turn depended on the length of fish and its position in electrical field. The body voltage of fish varied directly with the length and inversely with the rise of angle between their body axis and field lines. The fish subjected to higher effective period took longer time for recovery from narcosis. The effect of impulse current was manifested by increased rate of gill movements in Platax tefora, Haetodon ollaris, Crysophus burda, Siganus vermiculatus and Scolopsis leucotaenia, and lowered rate of movements in others when subjected to different effective periods inspective of length.

A study on the average yield of different species pf prawns used for freezing and canning

The paper deals with the average yield of four spp of prawns viz. Metapenaeus dobsoni, Metapenaeus affinis, Parapenaeopsis stylifera and Penaeus indicus on conversion to peeled and deveined (PD), cooked and peeled (CP) and head less shell on (HL) forms in the different months of a year and the likely variations observed in the average yield.

Length-weight and tail length-total length relationship in Panulirus homarus Linnaeus on the south-west coast of India

Length-weight relationships of Panulirus homarus caught from the Kanniyakumari coast was found to be W=0.000566 L super(2-50). The relationship between tail length and total length was also investigated and compared with that of Panulirus polyphagus. Same relationship did not hold good for the two sexes as in the case of P. polyphagus. For a given tail length, the head length, the total length and the weight appear to be relatively larger for females of small sizes of P. homarus.

Notes on the external sex characters of Chanos chanos Forskal spawners

In the present study, no visible differences between the sexes of C. chanos with reference to external features such as colouration, shape of head, snout and operculum, presence of tubercles or nasal pores, length, size and shape as well as any roughness in the various fins, could be found. However, the anal region of the mature milkfish (sabalo) exhibits discernible anatomical differences in the male and female. The male has two main openings visible externally: the anterior anus and the posterior urogenital opening at the tip of the urogenital papilla. The female has three main openings instead of two: the anteriormost anus, followed by the genital pore and the urinary pore located posterior to the genital pore at the tip of the urogenital papilla. Internal examinations were also made on both sexes. In ripe sabalo, it is easier to distinguish the sexes since milk oozes out of the urogenital pore by pressing the abdomen of the ripe male fish. Gravid females are identified by their distended abdomens.

A preliminary study on the use of the local variety of ipil-ipil Leucaena leucocephala as a protein source for prawn feed

A study was carried out to determine the effect of 10 or 20% leaves or seeds in the diet of Penaeus monodon , and the extent to which local ipil-ipil (Leucaena leucocephala ) could replace head shrimp meal. A brief description is given of the experimental methodology, and details of composition of the diet, proximate chemical composition of the diets, mean weight gain and survival of Penaeus monodon larvae fed shrimp head meal and ipil-ipil as protein sources, are presented. Mean weight gains for all groups were poor and not statistically significant. Survival rates for those fed 10% ipil-ipil were significantly higher than those fed 20% diets. Wherever the survival rate was high, mean weight gain was low and vice versa. The presence of the toxic alkaloids mimosine in ipil-ipil could have caused the low survival rate.