Intra- and interspecific variation of otolith morphometric asymmetry in <i>Ethmalosa fimbriata, Galeoides decadactylus</i>, and <i>Cynoglossus monodi</i> living at different depth levels in the Komo Estuary, Gabon

Abstract This study is the first to investigate the intra- and interspecific differences in otolith’s length (Lo), width (Wo), perimeter (Po), area (Ao), and mass asymmetry (OMA) in the pelagic Ethmalosa fimbriata , demersal Galeoides decadactylus , and benthic Cynoglossus monodi collected from the Lebe fishing site located along the Komo Estuary, central-western Gabon. The objectives were to (1) verify whether or not otolith morphometry differs in relation to living depth levels of the three species, (2) examine fluctuating asymmetry (FA) in the otolith morphometry, and (3) assess the relationship between OMA and total length (TL). A significant asymmetry was found in Lo, Wo, Po, and Ao between the left and right otoliths within and among males and females at the intraspecific level and only in Wo and Ao at the interspecific level due to FA. At the intraspecies level, a significant OMA was only observed within females of G. decadactylus and C. monodi and males and females of E. fimbriata and C. monodi . Moreover, a significant relationship between OMA and TL was detected only among males and females within the pelagic E. fimbriata and the demersal G. decadactylus , and no significant relationship was found at the interspecific level. As a result, significant differences in Wo and Ao and non-significant differences in OMA were recorded between the three species based on variations in living depth levels. These results highlight the importance of using otolith morphometry and OMA analyses to address the relationship between fish species and their living depth levels.