South Asian Journal of Life Sciences

Research Article
S. Asian J. Life Sci. 8(1): 11-18
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Mahunan Tobias Césaire Azon1*, Diane Nathalie Kpoguè2, Juste Vital Vodounnou2, Edmond Sossoukpè1, Emile Didier Fiogbé1

1Research Laboratory on Wetlands (LRZH), University of Abomey-Calavi (UAC), 01 BP 526 Cotonou, Benin; 2School of Aquaculture, National University of Agriculture (Eq/UNA), BP 43 Kétou, Benin.

Abstract | Parachanna obscura can be found in several wetlands such as flooded plains, lakes, rivers, shallows and ponds. However, its scarcity in water plans through latter years constitutes a major preoccupation for researchers. The current study aims to evaluate comparatively the population dynamic of Parachanna obscura in two West-African water plans: the Kakum River of Ghana and Lake Nokoué of Benin. This evaluation has been carried out based on parameters such as length-weight relationship, sex ratio, gonado-somatic and hepato-somatic indexes and the first maturity height of Parachanna obscura in Lake Nokoué (Benin) and Kakum River (Ghana). Our results revealed a negative allometric growth b = 1.06 and 1.62 (b < 3) respectively in specimens of P. obscura of Kakum River and Lake Nokoué. The male female sex ratio is based on males in Lake Nokoué though in the Kakum River, it’s based on females. The highest gonado-somatic index (0.92±0.2 % in February, 0.56±0.18 % in March and 0.82±0.17 % in April regarding females and 0.29±0.07 % in February, 0.29±0.08 % in March and 0.30±0.05 % in April regarding males) and hepato-somatic (0.82±0.16 % in February, 0.73±0.18 % in March and 0.81±0.24 % in April regarding females and 0.72±0.21 % in February, 0.77±0.19 % in March and 0.75±0.17 % in April regarding males) were recorded in specimens of Kakum River though the lowest GSI (0.78±0.27 % in February, 0.55±0.25 % in March and 0.64±0.24 % in April regarding females and 0.11±0.03 % in February, 0.14±0.06 % in March and 0.13±0.04 % in April regarding males) and HSI (0.5±0.23 % in February, 0.57±0.22 % in March and 0.61±0.25 % in April regarding females and 0.27±0.09 % in February, 0.39±0.22 % in March and 0.33±0.12 % in April regarding males) were recorded in Lake Nokoué. The first sexual maturity height in females of P. obscura was 15 cm TL and 12.5 cm TL respectively in specimens of Lake Nokoué and Kakum River.

Keywords: Parachanna obscura; Length-weight relationship; Sex ratio; Gonado-somatic index; Hepato-somatic index; First sexual maturity height; Lake Nokoué; Kakum River.