Experimental fishing in Hirakud Reservoir, Orissa (1965-67)

The comparative efficiencies of simple gill net, vertical line net and framed net in exploiting the fishery of Hirakud Reservoir in Orissa were studied. Though comparatively costlier to fabricate, the framed net gave better results than the other two.

Indigenous substitutes for "Lignum vitae" for making stern bearings for fishing boats

Difficulties are very often encountered in selecting proper material for making stern bearings for fishing boats. Conventional materials such as white metal, bronze etc. wear out too fast also causing considerable wear to the propeller shaft. Lignum-vitae, a natural wood commonly used for this purpose, is not available on a commercial scale in our country. Results of trials carried out to find out suitable substitutes for lignum-vitae from among indigenous timbers are presented in this paper.

On the troll line investigations off Cochin during five fishing seasons. Pt. 1. Investigations during 1960-61 and 1961-62 seasons

There is apparently great scope for improvement of the design and operational aspects of the gear particularly for the effective exploitation of seasonal fisheries like that of seer, tuna, barracuda etc. In order to evolve improved, yet cheap trolling gear regular investigations were undertaken by the Craft & Gear Wing of the Central Institute of Fisheries Technology, off Cochin for five fishing seasons and the results of these studies are incorporated in this paper.

Scantlings for small wooden fishing vessels

Studies are carried out to find a suitable basis of specifying scantlings for wooden fishing vessels for India, especially for the range 30' to 50' length overall. Equations of the type y=a (where 'y' is scantling in inches, N is cubic numeral in ft³ and 'a', 'b' are constants) are fitted to the scantling tables (applicable to vessels 50’ and above) available from USA, Newfoundland, Denmark, France and Scotland and they are found to represent the regulations accurately. These lines are corrected for standard frame and beam spacing and molded/sided dimensions to bring them on a common basis for comparison and minimum scantling lines for the main structural members are derived. These lines are extended to cover the range 30' to 50' which is generally outside the range of the above regulations.

On the troll line investigations off Cochin during five fishing seasons. Pt. 2. Investigations during 1963-64 season

During this season the investigations were mainly directed towards elucidation of the selective action of trolling lures. Feather jigs, buffalo horn jigs, stainless steel jigs, Japanese whale bone jigs and plastic jigs were selected. Operations were carried out from Fisheries technology No. 5.

Study on fishing gears, species selectivity toward gears and catch composition of BSKB beel, Khulna, Bangladesh

An investigation on the types of fishing gear used and their species selectivity and effects on fishes of BSKB beel in Khulna was conducted from June '95 to January '96. Fishermen were found to follow 6 fishing techniques viz., netting, trapping, angling, spearing, dewatering and hand picking. Among them 23 types of the fishing gear was recorded to be used by the fishermen of which 7, 8, 4 and 4 are nets, traps, hooks and lines, and hand harpoon respectively. A total of 47 species of fish were identified in the catches of different gears used by the fishermen in BSKB beel. Particulars, mode of operation, fishing season and catch composition of different fishing gears were determined. Seine, cast and lift net, traps (charo, arinda and ghuni), and hooks and lines (dhawn and nol broshi) were recorded as nonselective gear considering the fish species caught. However, gill nets (punti, koi and fash jal), clasp nets (bhuti jal), some traps (khadom, tubo), hooks and lines (chip borshi, chasra) and all spears were used as more or less selective gear. With respect to species and its size fash jal, bhuti jal, trap (khadom, ramani), and koach, juti and jhupi among spears were regarded to be more or less large-species-gear. But punti jal, koi jal, trap (koi dughair, charo, tubo, arinda and ghuni), nol borshi and spear (ful-kuchi) were small-species-gear. Among all gears seine net, cast net, lift net, koi dughair and ramani were recorded deleterious for carps especially for stocked fingerlings. For relatively small sized wild fishes koi jal, punti jal and ghuni traps were identified as detrimental gear.

On the troll line investigations off Cochin during five fishing seasons. Pt. 3. Investigations during 1965-66 and 1966-67 seasons

During these two seasons investigations were carried out with a view to exploring the possibility of this operation on commercial basis and to study the effect of certain meteorological factors on catch.

Results of comparative fishing trials with rectangular flat and rectangular curved otter boards

The communication deals with the results of comparative fishing operations conducted to study the effectiveness of rectangular flat and rectangular curved otter boards. Based on the analysis of data gathered during the course of actual field trials, following conclusions have been drawn: the average catch per hour of trawling was more by 22 kg during attachment of rectangular curved otter boards. The average horizontal spread between rectangular curved otter boards in action was more by 13% and works out to 50% of the head-rope length of the net including sweeps. The towing resistance of the gear with horizontally curved otter boards was more by 10%.

Comparative fishing experiments with two trawl designs used in the inshore waters off Kakinada (Andhra Pradesh)

The importance of small trawlers for the economic exploitation of the inshore demersal fisheries is well recognized and accordingly mechanized boats of sizes 30' and 32' fitted with engines of h.p. ranging from 30 to 45 came into existence particularly at Kakinada. The need to work out the most suitable trawling gear for these classes of boats becomes imperative and as an appurtenance to this, comparative fishing experiments were attempted with different trawls. In the present communication certain observations made on the relative catch efficiency of two different trawl nets used in combination with two different shaped otter boards are given.

Instrumentation in fishing gear research

The general method of study of the performance of any dynamic system is to have an understanding of the various influencing factors. These include the dynamic parameters developed by the system as well as the external factors. In the case of a trawl net under operation there are many hydrodynamic forces acting on it. Since the trawl net is operated much below the water surface, visual observation is rather difficult. Model testing is an alternative method. However, as a model cannot be an exact replica of the original in all respects, model testing has only a limited application and an ultimate test with the actual gear in the true field conditions is necessary.

Results of preliminary fishing trials with 15.8m six-seam otter trawl

The paper deals with the results of trawling operations conducted along the Saurashtra Coast of Gujarat State with 15.8 m six-seam otter trawl. Fishing operations carried out from Fishtech No. 8 with this new net were the first of their kind in the country and the results proved to be encouraging. The design in question is passed on to private agencies for commercial operations.

Stock dynamics of horse mackerel, megalaspis cordyla (Linnaeus) along northwest coast of India

The stock dynamics of horse mackerel, Megalaspis cordyla, along the northwest coast of India has been studied using length frequency data recorded from commercial landings and trawl catches of research-cum-training vessel M.F.V. Saraswati. The growth parameters for this species has been estimated to be L∞=54 cm and K=0.49 per annum. The natural and fishing mortality for the stock have been worked out to be 0.93 and 0.91 per annum respectively. The study indicated that the stock is fished at a safer fishing mortality level F sub(0.1), lower than F sub(msy) level.

Social status and problems of fishing community at Allahabad

The paper highlights social status and socio-economic problems of fishermen living along the Ganga and the Yamuna at Allahabad. Since the problems of fishermen varied with respect to category (with owned boat and with hired boat) and location, significance of this variation was tested by x²-test. The paper further emphasises on an intensive study of fishermen community to have in depth analysis of their problems and to suggest remedial measures for their upliftment.

Estimation of fishing mortality and migration coefficient of the fishery of juvenile Macrobrachium rosenbergii from Kalu River in Maharashtra

The freshwater prawn, Macrobrachium rosenbergii breeds in estuaries and the juveniles after completion of their larval stage start their upward migration towards rivers. It is at this stage fishing of juveniles takes place in river mouths. Kalu River near Titwala, in Maharashtra is estimated based on data presented by Indulkar and Shirgur (1995) for 1991 and 1992 fishing seasons. The fishing mortality was estimated to be 1.50 and 1.28 for a fishing season of 3 months in 1991 and 1992 respectively, while the migration coefficient was computed to be 3.53 during the fishing season. As the average exploitation rate during the study period was only 0.24, the juveniles are not heavily fished and there is a scope for almost doubling the present catch to about 4 million seeds per fishing season.

Drift-net fishing in Ceylon waters

Fishing with drift-nets beyond the continental shelf was more profitable than fishing within the continental shelf. Fishing operations conducted over the year beyond the shelf yielded an average catch approximately 1000 lbs. per operation while fishing within the shelf yielded an average catch of 400 lbs. per operation. The seas off the south-west and south coasts were found to be much richer in pelagic fish than the seas off the east coasts. There was a seasonal abundance of fish off the south-west, south and east coasts of Ceylon. On the south-west and south coast fish were more abundant during the months of the south-west monsoon while on the east coast fish were more abundant during the months of the north-east monsoon. Drift-net fishing proved to be a more lucrative method of capturing fish than trolling, longlining and trawling in the seas off Ceylon, and has contributed to an increase in the gross catch in Ceylon waters.