Preliminary Analysis of the Feeding Habits of Two Species of the Genera Mobula, Mobula japanica (Müller & Henle, 1841) and Mobula tarapacana (Philippi, 1892) in the Coastal Waters of Côte d’Ivoire, Gulf of Guinea

Mobulids are filter feeders, particularly vulnerable to overexploitation due to their late sexual maturation and low fertility. However, knowledge of their biology remains limited, requiring sub-regional and international cooperation to ensure their preservation. This study provides baseline information on the feeding habits of Mobula japonica and Mobula tarapacana using data on stomach contents. Specimens were sampled from the small–scale driftnet fishery operating along the coast of Côte d’Ivoire between March 2020 and April 2022. Diet was described using the Prey-Specific Index of Relative Importance (%PSIRI) combining occurrence, numerical and weight percentages. A total of 215 M. tarapacana and 210 M. japanica ranging in sizes of 154–371 cm DW and 80–369 cm DW were examined, respectively. The large number of empty stomachs for M. japanica (71.43%) and M. tarapacana (73.02%) may be the result of using hooks, which cause high stress resulting in stomach regurgitation. Mobula japanica and M. tarapacana consumed mainly commonly abundant crustaceans such as Sergestes atlanticus and euphausiid Pseudeuphausia latiffrons, accounting for 95% and 71.13% of the diet, respectively. However, diet of M. tarapacana was more diverse, including crabs, algae of the genus Sargassum, teleost fishes, molluscs and insects. Analysis of Costello diagram showed that both species are specialist predators, although M. japanica has a more restricted niche. The Morisita-Horn similarity showed no significant changes in diet according fish sizes and marine seasons.