Length-Weight Relationship and Condition Factor of Fish Species Caught by Cast Net in New Calabar River, Nigeria

The length -weight relationship and condition factor (K) of fish species caught by cast net were studied from three stations in the New Calabar River, Rivers State, Nigeria. A total of 1541 specimens of 26 fish species and representing 11 families were randomly collected using cast net with mesh sizes of 1.5 and 2.5 cm. Sample sizes of the different fish species examined in this study ranged from 8.79±0.25 cm (Caranx hippos specie) to 31.48±4.93 cm (Sphyraena barracuda specie) in total length and 15.45±0.40 g (Elops lacerta) to 156.00±39.30 g (Pelmatolapia mariae) in weight. The entire length-weight data in all the three stations were pooled together and the calculated correlation coefficient showed a high positive correlation (1.00) between length and weight of all the fish species except in Caranx hippos (0.18) with low positive correlation. The b value obtained ranged from 2.13 for Ethmalosa fimbriata with negative allomerty to 3.53 for Pelmatolapia mariae with positive allometry. By negative allometry (b < 3), the fish is said to be lighter for its length as it grows and (b>3), the fish gains weight as it grows. The mean condition factor ranged from 0.36 ± 0.03 recorded for Sphyraena barracuda to 2.20 ± 0.02 for Coptodon guineensis and Coptodon zillii. Apart from Sphyraena barracuda general wellbeing of all the fish species were found to be good, as indicated by the values of condition factor, which were nearer to or greater than 1. The results of the present study will provide an effective tool for further studies of population dynamics and stock assessment studies in the study area.