On the performance of otter trawls operated from a 15.4 m trawler off Veraval

Results obtained with three trawl nets namely, 13.7m four seam, 15.8m six seam and 18.3m four seam operated from a 15.4m wooden trawler, are presented. Among the three nets operated, 15.8m six seam trawl and 18.3 four seam trawl were found to be equally effective for the capture of shrimp and during the lean season 15.8m six seam trawl can be successfully operated to exploit demersal as well as semi-pelagic fish resources. The catch data were analysed using analysis of variance and Gulland's method

Twin trawling for shrimp with dummy doors

Twin trawling; a new concept in shrimp trawling is described in this paper. It essentially involves towing of two trawls of equal size connected in sequence at the inner head and foot rope legs and using a pair of outer otter boards and central neutral door or dummy door with triple bridles and single tow warp. A comparative study with conventional stern trawling using a standard 13.7 m four seam shrimp trawl and two 6 8 m standard four seam trawls as twin-rig has shown considerable reduction in the utilization of power (20 %) with better efficiency in shrimp fishing

Studies on bridle lengths in one-boat midwater trawling

Investigation on the comparative fishing trials to study the effect of bridles for a 10.5 m four equal panelled one-boat midwater trawl are described. Three bridle lengths of 20, 30 and 40 m were tested for relative efficiency evaluation. 30m bridles are found to be more suitable for the particular design and arbitrary selection of bridle lengths would be detrimental to the efficiency of nets

A new one-boat mid-water trawl for Indian waters

Even though the rich and variegated pelagic fishery resources of our west coast are well known much has to be done for a judicial and systematic exploitation on a commercial scale. To fill up this lacuna the present paper describes in detail a new design of 10.5 m four-equal panel mid-water trawl, its rigging and operation from a medium size vessel. Comprehensive comparative efficiency studies of this gear with a 10.5m unequal panel mid-water trawl established the superiority of the new gear. From the results based on the mouth opening, resistance and the catch it is opined that this new gear can not only be used on a commercial scale in harvesting the seasonal pelagic fishery, but also as a secondary supporting gear in shrimp fishery in places like Veraval, where there is a commercially exploitable yield of quality fishes like hilsa, pomfret, seer etc., without much modification from conventional stern trawlers

Some observations on the performance of 10.5 m mid-water trawl operated off Veraval

The communication presents the results of fishing trials conducted off Veraval with a 10.5 m four-seam unequal paneled mid-water trawl with vertically curved otter boards. The design and structural details of net and otter boards are described in detail. Particulars such as the fish caught during experimentation, horizontal spread of the net as well as towing resistance offered in action are also incorporated

On the results of preliminary fishing trials with shark long lines in Veraval waters

Experimental fishing operations with shark long lines were conducted in the sea off Veraval with a view to studying their efficiency and gathering information on the available resources of sharks to be used for planning the future gear investigations. The trials were undertaken in 1967, employing departmental fishing vessel "Fishtech No. IV" (10.9 m O.L. and 48 H.P. engine). A total of 5525 hooks were employed and 242 sharks weighing 8629 kg were landed. Data on composition of catch, weight of fishes landed, effectiveness of various baits in capture of different species of sharks and effectiveness of gear including its catch efficiency in this area were compiled. Bait preference was also observed in certain species of sharks caught. Chirocentrus dorab proved to be the cheapest and most effective bait in capture of all the three varieties of sharks landed

On the results of bottom-drift-long-lines operated off Veraval with particular reference to selective action of baits and hooks used

Hither to comprehensive data on the various types of baits used for capture of predatory fish and selective action of different hooks for bottom-drift-long lines is conspicuous by its absence. In the present studies attempts were made to evaluate the effectiveness of three types of baits and four sizes of hooks. Significant results obtained during the course of these investigations are presented in this communication

Double-rig shrimp trawling, its rigging, comparative efficiency and economics

A radical and revolutionary change from the hitherto employed shrimp trawling is reported for better productivity and economy in deep sea trawling with medium and large vessels. Studies carried out off Veraval with a 13.7 m. four seam shrimp trawl as conventional single-rig and two 6.8 m four seam shrimp trawls as double-rig from a 15.2 m fishing vessel showed an increase of 98% shrimp catch by double-rig over single-rig at 86.3 % of the power utilised by the latter. It has also been worked out, theoretically, how better this available power can be utilised for further improvement of catch. An increase of 15% head rope length in case of double-rig over the optimum single-rig gear of any vessel is recommended

Shark long line gear of India

Sharks are mainly harvested with long lines which is less expensive compared to other methods of fishing. Though this is a common gear operated along the coast, the gear in every region has its own peculiarities in construction and rigging. This communication furnishes detailed description of the gear operated in different centres. Suggestions are also offered to improve the gear and methods for enhancing production

Effect of variation in mesh size on trawl efficiency

Result of comparative fishing trials with a bulged belly design with three different mesh ranges in the body and wing to study the effect of mesh size difference on the performance of gear is discussed. While there is no significant difference in catch rate, predictably the 40 mm mesh size trawl fared wen when small sized fish like anchovies formed the major catch. The trawls with 60 and 80 mm mesh size gave better horizontal spread at a lower resistance showing savings in fuel