水産養殖研究開発ジャーナル

概要

Length-Weight Relationships of Some Economic Fishes of Ibeshe Waterside, Lagos Lagoon, Nigeria

Josef Bamidele Bolarinwa*,Popoola Q

This study describes the length-weight relationships (LWR) and condition factor (K) of six (6) fish species of ecological and economic importance found in Ibeshe waterside area of Lagos lagoon, Nigeria. A total of 154 specimens of Chrysichthys nigrodigitatus , Pomadasy jubelini, Elops lacerta, Cynoglossus senegalensis, Polydactylus quadrifilis and Sphraena piscatorium were collected from the local fishermen during the late rainy period for three months (August 2012 to October 2012) and their total lengths (TL) and weights(W) recorded. A high positive correlation significant at 0.01 levels (2-tailed) exists between the weight and total length of each fish using Pearson’s correlation coefficient (+0.90 to +0.98). The values of constants’ a’ and’ b’ were determined from the length and weight data when transformed into the growth equation: log W=log a+ blog TL. The values of b for the fishes varied from -0.15 to 3.38. The growth pattern of Chrysichthys nigrodigitatus was represented by the equation Log W= 2.24 - 0.15 Log TL, Pomadasy jubelini by Log W = -2.32 + 3.38Log TL, Elops lacerta by Log W = 0.41 + 1.04 Log TL, Cynoglossus senegalensis by Log W = -1.37 + 2.37 Log TL), Polydactylus quadrifilis by Log W = -1.25 + 2.33 Log TL and Sphraena piscatorium by Log W = -1.11 + 2.23Log TL. These values of “b” shows that most of the fishes collected from the Ibeshe waterside of Lagos lagoon displayed negative allometric growth pattern apart from Pomadasy jubelini. The condition factor (K), a reflection of the well-being and degree of fatness ranged from 0.56 in Sphraena piscatorium to 1.62 in Pomadasy jubelini and all these condition factors fall outside the range recommended as suitable for matured fresh water species in the tropics. This might indicate that Ibeshe waterside may be environmentally unfavourable to fishes in the aquatic ecosystem.