Length-weight relationship Megalaspis cordyla (Linnaeus, 1758) along north west coast of India

Total length and total weight relationship of Megalaspis cordyla (Linnaeus, 1758) a carangid fish, along north west coast of India has been worked out. The fish is an ideal one, growing by weight a cube of its length, isometrically, retaining its specific body shape throughout its life. The relationship is w = 0.00906279 L super(2.9024152) total weight of fish in g and "L" represents total length in cm.

Population dynamics and stock assessment of Koth (Otolithoides biauritus Cantor, 1850) along the north-west coast of India

MSY, growth, selection and mortality parameters of Otolithoides biauritus have been worked out from data collected by MFV Saraswati of CIFE, and length frequency data from Ferry Wharf, Sasson dock, and Versova fish landing centres of Bombay. Values of L infinity, K, and t omicron obtained from length frequency study are 1572 mm, 0.2633/yr and 0.0289 yr respectively, and of weight growth parameters are W infinity = 10067 g, K = 0.03904/yr and t omicron = 0.0137 yr. Selection parameters are L + 150 mm, t sub(r) + 0.4167 yr lc + 240 mm and t omicron = 0.6367 yr. Selection factor (K) for codent worked out to be 12. Based on Z = 0.6486, the MSY of O. biauritus off northwest coast of India is assessed as 1,802 tons which is slightly higher than the current catch level of 1,634 tons.

Population dynamics of the ribbon fish, Lepturacanthus savala (Cuvier 1829) from the north-eastern part of the Bay of Bengal

Population parameters of Lepturacanthus savala from the trawl catches in the north-eastern part of the Bay of Bengal, Bangladesh were investigated based on length frequency data, using complete ELEFAN computer program. The asymptotic length (Lα) and growth constant (K) were estimated to be 106.50 cm (total length) and 0.80/year respectively. Based on these growth parameters, the total mortality (Z) was estimated to be 1.89. The estimated values for natural mortality (M) and fishing mortality (F) were 1.08 and 0.81 respectively. The estimated value for the exploitation rate (E) using the length converted catch curve was 0.43. The recruitment pattern showed two peaks per year. The estimated sizes of L. savala at 25, 50 and 75% probabilities of capture were 57.49, 60.39 and 63.28 cm respectively. The estimated length weight relationship for combined sex was W=0.00093 TL(super)2.97

Development of trawls for medium sized trawlers for Veraval, north-west coast of India

Comparative fishing experiments with 25 m bulged belly and 25 m six seam trawls were carried out to study the relative efficiency of the gear. Bulged belly trawl was found more efficient than the other at depths below 40 m. The tension and horizontal opening were more in bulged belly and six seam trawl respectively. Bulged belly caught more of prawns and lobsters but there was no significant difference in the catch of sciaenids, cephalopods and ribbon fishes in the two nets.

On the comparative efficiency of "V" shaped and rectangular flat otter boards for trawling off Veraval, north west coast of India

V shaped all steel boards, with their inherent stability to tide over obstacles and mud, interchangeability of starboard and portside boards are found to be superior to conventional flat rectangular boards for bottom trawling. These are cheaper in construction, offer less resistance and give longer service. Comparative trials with the two types of boards showed significant difference in tension between the boards but not in catch or horizontal opening.

Performance of 25m large mesh demersal trawl off Veraval, north west coast of India

Performance of a 25m large mesh demersal trawl, with 150mm mesh size in the fore parts of the trawl was evaluated in comparison with one boat high opening trawl of the Bay of Bengal Programme (BOBP) with 360 meshes of 160mm mesh size and 25.6m head rope length. An 8.2% increase in catch was obtained by 25m large mesh demersal trawl. The gear is comparatively cheaper, lighter in construction and offered better horizontal spread with significantly lower towing resistance. Commercial suitability of the gear for efficient harvesting of demersal fish resources of the region is discussed.