An experiment conducted with a floating trawl net off Cochin

The paper deals with an experiment with a floating trawl net off Cochin, using a pair of curved otter boards and a transducer mounted on the head rope of the net. 32 hauls were made with different towing speeds and warp length keeping one factor constant for varying parameters of the other factor. The working data for 32 hauls are presented and the effect in the fishing depth of the net due to the variation in one factor is mentioned. The 'fishing depth' is indicated in this paper as the distance between the head rope and the bottom. The usefulness of similar experiments with added information on the angle of leading warp at the stern for the exploitation of column fishes in Indian waters is indicated.

Sulphur and methionine content of some fresh water fishes of Madras

The importance of sulphur amino acids, especially of methionine, in our nutrition is too well known to be emphasized. But adequate data on the sulphur and methionine contents of the cheapest of our animal foods viz., fish, are not available. In this note, the total sulphur and methionine content of 18 common fresh water fishes is presented. Total sulphur was determined by Osborne perioxide method (Winton & Winton, 1945) and methionine by the colorimetric method of Horn. (Horn et al., 1946)

Recent developments in fish processing and preservation

A review of the literature on fish processing will reveal that most of the important developments have taken place during the last twenty years. Sustained work by teams of scientists in different parts of the world, has not only contributed much to our knowledge of the chemistry and technology of fish but also resulted in revolutionary changes in the methods of preservation and processing of fishery products.

Biochemical composition of the muscle of some freshwater fishes during the pre-maturity phase

Biochemical composition of the muscle of juveniles belonging to 18 different species of freshwater fishes showed that the protein percentage in juveniles was higher than the adults. The fat, on the other hand, was much lower. This suggests that the body fat increases with the onset of maturity. No clear inverse relationship was found between fat and protein in juveniles. Moisture percentage was very high in juveniles. This was probably because of low fat content. In most species the sum of fat and water contents (F + W) was found to be constant. The percentages of ash, calcium and phosphorus were higher in juveniles than those of adults. Dry matter percentage varied inversely with the moisture and in most species carbohydrate was generally low. In juveniles although the calorific value of protein-fraction was high the total calorific value was lower than the adults.

A survey of the quality of salt cured fish produced in the Kanyakumari Disrict [i.e. District], Madras State

A survey of the quality of salt cured fish in Kanyakumari District, Madras State was done during the years 1963 and 1964 to obtain necessary basic information to formulate quality standards for these products which are gaining importance in the export trade. 155 trade samples of sun-dried, dry-salted, wet-cured and pit-cured fishery products were examined for their chemical quality and organoleptic characteristics. 26.5% of the sun-dried products, 25% of the wet cured fish, 55.21% of the dried salted products and none of the pit cured samples were found to be good in quality. The sun dried products were generally found to have heavy admixture of sand and were inadequately dried. The chief defects in the salt cured fish products were found to be the use of spoiled fish, imperfect cleaning and washing, use of impure salt, inadequate salting, curing and drying, and unhygienic conditions in all stages. Quality standards must be formulated for each variety of salt cured fish product and adequate measures taken to rectify the defects and enforce the quality standards.

On the canning of Sardinella fimbriata Sardinella gibbosa and Sardinella sirm in oil pack

This note gives details of experiments conducted on the canning of certain species of sardines viz. Sardinella fimbriata, Sardinella gibbosa and Sardinella sirm which are landed in commercial quantities in the East Coast of Madras State and which have not so far been tried for canning. The experiments conclusively prove that these species of sardines can also be canned in oil pack and good canned products manufactured out of them.

The bacterial flora and their possible association with spoilage in a variety of fresh-water fish: Cyprinus carpio. var. communis

The bacteria from a variety of fresh-water fish, Cyprinus carpio. var. communis, showed the presence of micrococci, Gram positive and Gram negative rods. These have been characterized as far as was possible. Of thirty-eight strains of bacteria used, only six strains were considered as causing spoilage of fish flesh in experiments where flesh was incubated with individual cultures of the bacteria. These six strains had been found on the surface and/or intestine of the fish and support the suggestions that, after death, invasion of flesh by bacteria from the surface and intestine could be the cause of bacterial spoilage of fish.

Preliminary experiments on electrical fishing in fresh watter [i.e. water]

Fishing using electricity is a new technique and is still in the experimental stages in many of the advanced countries. While no published records are available in India, considerable work has been done in Germany, United States, Canada, and United Kingdom. These papers mainly deal with the behavior of the fish in the electrical field, the physiological effects of electrical current on fishes, methods of electrofishing, electric fencing etc. The following experiments on electrical fishing were conducted with a view to studying the distribution of electrical field when an alternating current is passed through two fixed electrodes in fresh water and to study the reaction of different fresh water fishes to the field.

Trawling pull exerted by a trawler: a method of estimation from propeller dimensions and its comparison with sea measurements

The proper matching of the pull exerted by a trawler and the size of trawl is important for maximizing the catching efficiency. The available pull is more dependent on the propeller and its working conditions than the installed engine power. The normal practice is to directly connect net size to the installed power in the boat by formulae without reference to the prope1ler dimensions or the available trawling pull and this is not adequate to find out the optimum combination. By the method outlined in this paper, the accurate calculation of trawling pull is possible by taking into account only the propeller diameter, pitch and r. p. m. The predictions by the method are compared for trawlers with powers between 30 and 60 hp and agreement is found to be within + 5%. The power absorbed by the propeller in trawling condition can also be calculated by this method for checking whether the engine is being overloaded.

Oceanographic importance of the Cochin littoral

Situated as it is on the north-western section of the Indian Ocean, the Cochin littoral has played a very significant role in the history of India. Despite being an extremely interesting region from the point of view of oceanographic studies, the Indian Ocean in general has been one of the least scientifically known regions of our planet.

Preliminary observations on the effect of a. c. current on Catla catla and Ophicephalus punctatus

In order to evolve suitable electrical fishing gear for inland waters, preliminary experiments have been conducted to observe effect of a. c. currents on Catla catla at voltages of 30, 90 and 120, pH 7.3 and 8.4, temperature 48°F, 78°F and 105°F, distance between electrodes 25 cm, 50 cm and 75 cm, size range of fish 100 mm, to 235 mm. Apparatus used was a 5 kw; a. c. 60 cycles generator with resistance control. Larger sizes of fish were more prone to electric shock. Higher temperature increases the intensity of the shock, while variation of pH between 7.3 to 8.4 did not materially affect the intensity of the shock. Fishing with a mixed population of Catla catla and Ophicephalus punctatus gave a greater percentage of mortality for the latter.

Studies on shark liver oil and its residue

Seasonal variation in oil and moisture contents and vitamin A potency of oil in livers from different species of sharks landed at Veraval coast were studied. Values of moisture, protein, ash and vitamins in defatted liver residue were determined.

Measurement of moisture in dry cured fish by infrared irradiation

Heating conditions have been standardised for measurement of moisture in dry cured fish using infrared irradiation source of 150w. Results obtained are comparable to those obtained from standard air oven method (drying to a constant weight at l02°c), the mean deviation being less than two units. The method works equally well for fresh fish muscle.

Utilisation of trash fish. Pt. 1. Preparation of fish flake

The paper deals with the investigations carried out on the preparation of odorless fish-starch flakes using partially deodorized trash fish meat and different sources of starch like corn, tapioca, maida and black gram. It has been found that the products using corn and tapioca are better compared to those prepared using other two starches, the product from corn being the best. The product has a protein content of about 20% and has been found to have a storage life of 4 months at 37°c.

Pearl culture and pearl oyster cultivation

Few marine animals have yet been tamed and harnessed for man's use. Of these the bivalves have the greatest potential, and of the bivalves the pearl oysters are perhaps the most thoroughly exploited. Not only are they eaten and their shell put to use, but their nacre secreting properties are tapped to produce pearls by design, rather than by accident as in nature.