Resumen del producto

 Shark fishing in Mexico is one of the most important economic spills. Within the coasts of Baja California Sur this resource occupies the fifth place between the most important groups in catches. The silky shark Carcharhinus falciformis, is the most frequent and abundant species in tropical waters. We use stomach contents and d13C and d15N stable isotope analysis to know the trophic ecology of this species in the western coast of Baja California Sur. The samples were obtained in the Punta Lobos fishing camp between 2011 and 2016. The trophic spectrum include eighteen species of fishes, eight species of cephalopods, one species of crustaceans. According to the relative importance prey index (PSIRI), the crustaceans were the most important group, being Pleuroncodes planipes the main prey occupying 85.52% of the trophic spectrum, followed by fishes with 6.77% and cephalopods with 4.43%. In general the stable isotope analysis yielded values of de d13C: - 17.68 ‰ ± 0.38, d15N: 17.09 ‰ ±0.74, which indicate and oceanic habitat with an specialized feeding strategy and a trophic level which oscillates between 3.5 and 3.7, being a carcinogenic predator. The analysis of the mixture model suggests a higher contribution of the red crab (P. planipes) and the group of two cephalopods, Ancistrocheirus lesueurii and Gonatus spp. we found significant differences between the isotopic values of juveniles and adults. Also during the warm and cold seasons the silky shark showed different feeding strategies, being a generalist during the warm season and an specialist in the cold season.

Palabras clave: Silky Shark; Stable isotope analysis; Feeding ecology; Baja California Sur

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