Age, Growth and Mortality of Auchenoglanis occidentalis (Valenciennes, 1840) from Lake Akata, Benue State, Nigeria


exploitation rate
A. occidentalis
Lake Akata


The examination of the age, growth, and mortality of Auchenoglanis. occidentalis from Lake Akata was investigated for 12 months. A total of 770 samples of A. occidentalis were collected from May 2022 to April 2023 from fishermen operating at Lake Akata. Estimating age and growth utilised Bhattacharya's length frequency distribution assortment method, along with the von Bertalanffy, Gulland, and Holt plot methods. The result showed that the mean standard length (cm) and weight (g) of A. occidentalis were 25.34±0.36 cm and 284.6±6.9 g respectively. Auchenoglanis occidentalis with a condition factor of 1.53± 0.02 demonstrated favorable health. Both male and female A. occidentalis displayed a negative allometric growth pattern. The predictive von Bertalanffy growth parameters were L∞ (46.73 cm), K (0.280), and to (0.88 years), represented by Lt = 46.73 [1 - exp (-0.280 (t – 0.88)]. The fish population was divided into three age brackets. The growth performance index (Ф1) measured 2.79, and the total mortality (Z), calculated using Hoenig's Model I in FISAT II, was 1.434 per year. The instantaneous fishing mortality (F) was 0.781 per year, and the instantaneous natural mortality (M) was 0.651 per year, leading to an exploitation rate (E) of 0.545. This signifies an exceptionally high level of exploitation. To safeguard these species from extinction, it's necessary to implement management actions like setting limits on mesh size, restricting fishing activities, and declaring specific seasons off-limits for fishing. To promote the sustainable exploitation and management of the A. occidentalis fisheries, recommendations were made for implementing fishing gear regulations and adopting a community-based co-management system.



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