Trophic ecology of neonates and juveniles of the silky shark, Carcharhinus falciformis, off the coast of Guerrero, Mexico
2022
Sandoval-Ramírez,Adriana | Moreno-Díaz,Giovanni | Rojas-Herrera,Agustín A | Violante-González,Juan | Loyo-De la Paz,Luis J. | Cerdenares-Ladrón de Guevara,Genoveva
Abstract. The silky shark, Carcharhinus falciformis, is one of the most important shark species in the small-scale fishery landings on the Pacific coast of Mexico. In the present work, we report the main food components of C. falciformis caught by small-scale fisheries in Acapulco, Guerrero, Mexico, according to size (neonates and juveniles) and sex (males and females), as well as reporting the niche breadth and trophic level. A total of 165 stomachs of C. falciformis were collected, of which 57 contained food and 108 were empty. A total of 11 prey groups were identified: 4 crustaceans, 3 fish, 2 cephalopods, 1 sea turtle, and 1 bird. According to the prey-specific index of relative importance (%PSIRI), crustaceans accounted for 77.17% of the diet. The crab Portunus xantusii was the most important component of the diet of neonates, juveniles, males, and females. The diets did not show great differences between neonates and juveniles and between males and females (Morisita-Horn index: 0.86 and 0.80, respectively). The silky shark presented a narrow niche breadth in all categories, indicating a specialist-type feeding strategy (Levin’s index <0.60). According to Amundsen’s model, C. falciformis showed preference for P. xantusii. The trophic level determined for C. falciformis indicated that it is a secondary predator.
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