Growth and Exploitation Parameters of Pseudotolithus elongatus (Bowdich, 1825) from the Ebrié Lagoon, Côte d'Ivoire

Abstract

The geographical proximity of Ebrié Lagoon to densely populated areas such as the peri-urban zone of Abidjan leads to considerable exploitation of its resources. The present study aims to assess the exploitation and growth parameters of Pseudotolithus elongatus from the Ebrié Lagoon. This study was conducted from July 2013 to June 2015 on 512 specimens that were weighed in grams and measured in centimetres individually. Growth parameters were estimated using length–weight and length–frequency data. The growth and exploitation parameters estimated using the Von Bertalanffy equation and the FISAT II program indicate an asymptotic length L∞ = 66.15 cm and growth rate K = 0.14 year-1. The estimated total mortality is Z = 0.63 year-1; natural mortality (M) and fishing mortality (F) are respectively 0.40 year-1 and 0.23 year-1. The exploitation level E = 0.37 < 0.5 shows that Pseudotolithus elongatus is in a state of under-exploitation in the Ebrié lagoon. The analysis of the length–weight relationship revealed that Pseudotolithus elongatus exhibits positive allometric growth, indicating that weight increases faster than length. Estimates of key population parameters, including natural mortality, fishing mortality, and exploitation rate, suggest that the species is currently under-exploited in the Ebrié Lagoon. These findings indicate that the existing level of fishing pressure remains below critical thresholds and does not pose an immediate threat to stock sustainability. Consequently, the study concludes that the exploitation of P. elongatus could be moderately increased without compromising the long-term viability of the population, provided that appropriate management and monitoring measures are maintained.