Effect of weight of otter boards on the horizontal opening of trawl nets

The paper gives briefly the experiments carried out to determine the optimum weight of otter board that should be used for a trawl gear for better efficiency.

Exploratory fishing experiments in Hirakud reservoir - Orissa State (1967-70)

Suitable areas for fishing have been located in the middle and upper regions of the Mahanadi course of Hirakud reservoir. In the former the suitable period is during summer and beginning of monsoons, and in the latter in summer and winter months. The fishery of the reservoir is contributed by four species namely S. silondia, L. fimbriatus, C. mirgala and C. catla.

Synthetic fibres for fishing gear

A variety of synthetic fibres are at present in use as fishing gear material, the earliest one being the polyvinyl chloride group introduced for traps in 1936 (von. Brandt 1957). Since then synthetic fibres became increasingly popular among the advanced fishing nations of the world. The latest synthetic fibre which has been successfully used in fishing is polypropylene developed in Italy in 1954.

Cathodic protection of the hulls of fishing trawlers in India

Nearly 10,000 mechanised fishing trawlers mostly built of wood and about 100 trawlers built of steel besides a few fiberglass reinforced plastic and a couple of ferro-cement boats constitute the modern fishing fleet of India at present. Metallic corrosion in sea water is a very well-known phenomenon in all ships and various other marine structures; the exact financial loss and the material breakdowns have never been fully realized among the trawler owners in India. The Central Institute of Fisheries Technology at Cochin has been studying these problems for some years and has been able to assess the significance of underwater corrosion particularly of the hull below water line in the trawlers and suitable remedial measures have been suggested in this paper.

Mesh regulation in backwater prawn fishing gear

Size grade composition of different species of prawn caught by various back water fishing gear have been enumerated. 57 to 75% of P. indicus captured was less than 10 cm in length. M. dobsoni and M. monoceros captured were less than 10 cm in length. A cod end mesh size of 20-25 mm has been recommended for stake nets for the capture of P. indicus of 10 cm length along with other species.

On the fishing power of monofilament and multifilament gill nets

The authors have discussed the results of comparative fishing, conducted in the Govindsagar reservoir, with simple monofilament and multifilament gill nets. The experiments were conducted both in clear and turbid water. In both these water masses, the monofilament gill net has been found to be more efficient. It is also found that the four major species of fishes of the reservoir have not shown any preference towards a specific gear.

A wider choice of construction materials for the modern fishing boats

An account of fishing vessel construction materials is given, with information on essential features, and a material account. Materials discussed in detail are steel, wood, aluminium, glass reinforced plastic, and ferro-cement.

Problems associated with the over protection of fishing trawlers against sea water corrosion and fouling

Some presently used anti-fouling materials contain metals and other compounds, which are toxic in the environment. Coating products are not always stable, and there is a resulting pollution hazard. In particular if surfaces are poorly prepared and manufactures' instructions are not closely followed the application of anti-fouling substances becomes pointless and dangerous. In addition the salinity, constant biological activity and suspended particles make seawater a highly corrosive material in its own right.

Reliability and need for standardisation of electrical systems in small wooden fishing vessels

The working condition and atmosphere in a wooden fishing vessel are generally most injurious to the electrical systems. Therefore great care has to be taken in designing electrical systems for small c1afts. This paper deals with the difficult operating conditions and standardisation of electrical systems as applicable to small fishing vessels.

Hydraulics for small fishing trawlers

Fishing vessels where electric power supply from alternator is available to operate various auxiliaries located anywhere in the vessel, the small crafts, which constitute over 95% of the total fishing crafts operating in India, are entirely dependent on one source of power, i. e. the main diesel engine. To utilize this source of motive power to operate the winches and other auxiliaries, mechanical drive involving shafts, bearings and pulleys, is inconvenient. This paper presents basic advantages of hydraulic system over mechanical drive.

Studies on long wing trawl for shrimps off Kakinada (A.P.) coast - (i) Results of comparative fishing experiments with the conventional two seam trawl

Comparative fishing operations with the conventional two seams net and a 29.26 m. long wing shrimp trawl of four seam type were undertaken. The result showed that the four seams net gave nearly twice prawn catch than that of the conventional type. It was also found that the four seams net can be developed into a combination trawl for the effective exploitation of both prawns and fish along the coasts off Kakinada.

Coloured gill nets for reservoir fishing

Experimental fishing with different coloured nets has shown that white net yields better catch. The efficiency of the coloured nets was in the order yellow, grey, green and blue. Though there is little evidence to show some species preference to a particular colour, the results were not conclusive as the analysis of variance indicated that interaction between species and colour is significant only at 5% level.

Investigations on the number of trials required for statistical comparison of fishing gears

The number of fishing trials required for comparing the efficiency of fishing gears was investigated. A unique solution to this problem did not appear to exist because of the heterogeneity of the experimental material. Sequential experimentation and analysis have been found to be a practical approach to this problem. By this, the experiment can be terminated almost after 35 days fishing for catches with standard error per unit as per cent of the mean about 30% or less (after logarithmic transformation). For data with mean catches less than 1.5 kg analysis of variance approach does not appear to be meaningful.

The effect of increase in the number of fishing trips on the economic efficiency of 9.82 m and 11 m fishing trawlers along Kerala coast

Cost-benefit analysis of a 9.82 m and 11 m fishing trawlers based on the number of fishing trips is presented. The number of fishing trips per year determines the profit and loss of the trawler. With the increase in the number of fishing trips, the profit also increase for both the sizes of trawlers. The minimum quantity of prawn and fish to be landed for 0-20% profit for varying number of fishing trips are worked out. The break-even for 9.82 and 11m trawlers was observed to be 185 and 210 fishing trips respectively during 1980-81.