Condition factor and length-weight relationship of Nemipterus japonicus (Bloch) off Bombay coast

Fluctuations in the K values of Nemipterus japonicus (Bloch) off Bombay coast were interpreted regarding sex, month and females maturity stage. These indicate differential growth rates in males and females. Males and females attain first maturity at 145 mm and 115 mm respectively, second maturity is attained by both the sexes at 195 mm. First spawning occurs when both are of 155 mm length and at second spawning males and females attain 215 and 205 mm of length respectively. The fish mature and breed at "O" year; the main spawning period is from August to November with peak spawning activities in October. It grows about 155 mm in first year at 12.91mm per month and about 215 mm in the second year at 5.0 mm per month on an average. Length-weight relationships for males and females are given. The rate of growth of females by weight was found to be slower below 150 mm, but faster than that of males above 150 mm specimens.

Some aspects on growth and condition index of Saccostrea cucullata (Born), Cerithium rubus (Desh) and Tellina angulata Gmelin from Bombay coast

Size variation, growth, condition index and spawning periodicities of three species of molluscs were studied for a period of 15 months from a polluted and a relatively clean marine habitat near Bombay, Maharashtra, India. Growth of Saccostrea cucullata was 1.2 times and of Cerithium rubus was 1.6 times higher in unpolluted habitat than the polluted water. Spawning was during premonsoon in S. cucullata, post monsoon in C. rubus and monsoon in Tellina angulata. Condition index and percentage edibility values were higher at less polluted stations.

Length-weight relationship and relative condition factor in Macrobrachium (Hellex)

The length-weight relationship was calculated for the freshwater prawn Macrobrachium idae. About 150 specimens of M. idae (males 50, females 50 and 50 juveniles) were utilised for this study. The length-weight relationship was assessed separately for males, females and indeterminants. The regression equation for males, females and indeterminants showed significant differences whereas it was insignificant for males and females. The variations in length-weight relation between sexes and indeterminants were compared and discussed. The relationship between total length with carapace length and total length with rostral length were also determined.

On the effect of tickler chain on the catches landed by a 55 ft. trawl net

The communication deals with the results of comparative tests conducted from Cochin base to study the effect of a tickler chain on the catches landed by a 55' shrimp otter trawl. The net was operated with and without chain and 82 hauls of 61 hours and 28 minutes total duration were made. The following are the conclusions: (a) the catch of shrimp per hour of trawling is increased by about 71% due to attachment of the chain to the ground rope; (b) the attachment of the tickler chain also increased the catch of fish by 25%. The increase in the catch of shrimps and fish is probably due to the disturbance caused by moving chain attached to the foot-rope.