Comparative efficiency of trawls made of nylon, polyethylene monofilament and tape twines

Results of comparative fishing operations conducted with three nets of identical design made of nylon, twisted polyethylene monofilament and high density polyethylene (HDPE) tape twines are presented in this communication. Since the tape net recorded the highest prawn and fish catch, monofilament and nylon following in order, it can be recommended to the fishing industry as one of the cheapest and effective fishing materials evolved for trawl fabrication

Development of electro-trawl system in marine environment

High voltage pulsed current produced on board a trawler is fed to electrodes distributed along the foot rope of a trawl net through two core TRS cable which builds up a homogeneous electrical field around the net mouth. By comparative fishing tests with the electrified and non-electrified 32 m long wing trawl net, the increase in total catch of shrimps and fishes was found to be 19.8 and 36%, respectively

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

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Not AvailableGill nets are the most commonly used gear depended upon by the maximum fishermen in all the districts of Kerala. Results of a study on the marine gill nets of Kerala undertaken during May 1999 to June 2000 are reported in this communication. Nets of different mesh sizes ranging from 14 to 250 mm targeted at different groups of fishes are prevalent along the coast. The nets are classified into different groups and the technical specifications of each type are detailed. Polyamide (PA) monofilament has almost completely replaced PA multifilament in all the nets except those targeted for anchovy white sardine and seer. Fishermen often use nets of different mesh sizes, connected end to end, in a fleet of net landing all size groups of fishes.Not Availabl

Studies on the macrobenthos of mudbanks of Southwest cost of India

The present study was undsrtaken.with the objectives to assess the distribution and density of population of benthic animals with special reference to macrofauna from the south west coast of India from ' Malippursa 1 in the north to Alleppey in the south, to evaluate significant difference, if any, in the number and distribution of animals in th md bank regions and other intermittent stations, to examine the influence of bottom stability on the distribution of fauna, to observe the effect of the environmental parameters on the distribution pattern of nacrofauna, and to evaluate the nature and depthpwise distribution of the benthic fishery. The region selected for the investigation is one of the nest important fishing grounds in India for bottom fishing especially for prawns, covering a distance of about 60 kns in length.total number of thirty stations in five transects at right angles to the coast, each consisting of six stations were surveyed. The six stations in a transect were at depths of 5 m, 10m, 20:, 30:, 35m and 45m respectively formation of the Iudbanke, popularly known as 'Ghaknra' in the local language, is a peculiar phenomenon along the ooaet of Kerala and provides a good fishing ground.quantitative distribution of the mecrofauna chewed that the maximum number of organism was near the 35 n contour line in the first three profiles whereas in the fourth and fifth profiles it was at 20 n and 30 m depth respectively. The density of the fauna wee comparatively poor in shallow water etatione at depths 5-‘IO M.was a general decline in the numerical abundance and biomass of the bottom fauna in all the stations during the monsoon period. There has been very little yearly change in the composition of the fauna during the two years‘ study.Cochin University of Science and TechnologyDepartment of Marine Science, Cochin University of Science and Technolog

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Not AvailableCatch per unit effort (CPUE) of ring seines operated from the traditional plank built canoes was studied at two major centres, Ambalapuzha and Chellanam in Kerala. Parameters selected for assessing the productivity were catch per man hour and catch per fisherman per month. Statistical analysis shows that changes in CPUE are gear specific and location specific. Comparison between CPUE of large meshed (18-22 mm) thanguvala 800x90 m and small meshed (8-12 mm) choodavala 400x60 m that the latter performed better than that at Chellanam. CPUE decreased by more than half since the introduction of this gear. the causes and consequences of this decrease in productivity are also discussedNot Availabl

Studies on Riverine Fishing Gears of Central Kerala

The overall focus of the thesis involves Studies on the riverine fishing geara of central kerala.Rivers and reservoirs of India harbour a rich and varied spectrum of fishes exceeding 400 species, which include commercially important fishes.The fish and fisheries play a crucial role in kerala's economy,employment generation ,food security and well being of its people.In the present study ,results of investigations conducted during 2001-2002 on riverine fishing gears of central kerala are presented along with detailed description of fishing gears,their distribution and operation covering aspects of selectivity and operational economics.Chapter I gives an introduction to the topiC of the study highlighting the relevance of the study and reviews of the existing literature on fishing gears and practices in riverine sector and sets out objectives of the study.The chapter 11 deals with the Materials and Methods used for the conduct of the investigations. In this chapter the area and the rivers selected for the study. reasons for the selection process and methodologies used for survey of riverine fishing gaear and investigations on design, structure and operation of different gear systems are presented.The chapter III discusses gillnet and its operation. Gill netting is one of the simplest and oldest methods of fishing. They are the most widely operated fishing gear in the rivers of Central Kerala. Gill netting being a low cost fishing method is of special interest for artisanal fisheries. Twenty different types of gillnets are operated in this sector.Chapter IV deals with cast nets. The origin and evolution of cast net has been briefly described in the introductory part.The chapter V deals with fishing lines, traps and other miscellaneous gears.This findings will be useful for riverine fishermen for deployment of appropriate gear systems during different seasons to ensure profitability of fishing operations.Cochin University of Science and TechnologySchool of Industrial Fisheries, Cochin University of Science and Technolog

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Not AvailableThe problem of overfishing along the inshore waters of Kerala has been reported to be aggravated by the introduction of the ring seines. In the context of indiscriminate proliferation and use of ring seines this study is made with reference to the changes in the species composition, length of important species and biomass landed. The data for this study were collected from Ambalapuzha and Cochin, two major centres of ring seine activity of the state. The species selected for this investigation were makerel, oil sardine and other sardines. The results of the study show the likelihood of overfishing in the ring seine fisheryNot Availabl

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Not AvailableThe effect of natural sunlight on four polyamide monofilament yarns and four polyamide multifilament twines was studied. The samples, each of different RTex were exposed to 180 days solar radiation and sub-samples were drawn at intervals to study the effect on breaking strength and elongation at break. Significant reduction in both breaking strength (P < 0.01) and elongation at break (P < 0.01) have been recorded in the test samples due to weathering. Breaking strength reduced linearly with the period of exposure, while no such linear relationship was found in the case of elongation at break.Not Availabl