Diversity and Degree of organization of the ichthyological population of two tributaries of the Bandama River in the Marahoue region located in the center-west of Côte d'Ivoire were studied. Indeed, the two tributaries of the Bandama River that are Marahoue and White Bandama Rivers draining this region are subject to numerous disturbances, the main one being gold panning. Data collection was conducted from September 2019 to November 2020 from experimental and artisanal fisheries. The mesh sizes of the gillnets used for the experimental fishery varied from 10 to 40 mm mesh size. The results showed a dominance of the order Siluriformes represented by 6 families and 18 species in the Marahoue River against 4 families and 13 species in the White Bandama River. Also, the Shannon Index (H') values obtained in the White Bandama River (H' fluctuates from 2.26 to 2.33 bits/ind) are lower than those obtained in the River Marahoue (H' fluctuates from 3.02 to 3.14 bits/ind). Our results also highlighted the equitability. This index appeared relatively high in the Marahoue River (E varies from 0.77 to 0.80) compared to the White Bandama River (E varies from 0.5 to 0.57). Consequently, the Marahoue River appears to be more stable and has a good degree of organization of the ichthyological population compared to the White Bandama River.

The growth of Brycinus longipinnis caught at Aghien Lagoon was studied between June 2014 and May 2015 through growth type, condition factor and growth parameters according to the Von Bertalanffy model. Sampling was conducted using experimental fisheries. Growth type was determined from the length-weight relationship and growth parameters according to the Von Bertalanffy model from the FiSAT software. The growth was of negative allometric type (b = 2.59). The Brycinus longipinnis population grows faster towards the asymptotic length ((L∞ = 92.40 mm SL) with a growth coefficient K of 0.36 year-1. It is also a long-lived fish species with maximum longevity (tmax) of 8.32 years.

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