Resumen del producto

Ontogenetic changes in habitat and food preferences are common in nature; they reflect changes in the needs of organismsduring their lifetime. Studying the dietary ontogeny of pelagic species is a difficult task, because of migratory processesand the inaccessibility of their habitats. As a result, their life history remains poorly understood, or even unknown. Here, westudied the dietary ontogeny of 18 blue sharks, Prionace glauca, using isotopic analysis in vertebrae. A total of 132 samplesof vertebral collagen were taken (64 from males and 68 from females). The wide range of d13C values (- 16.8 to - 13.1‰)suggests that these sharks use both coastal and oceanic areas for feeding. Small juveniles and adults preferred coastal areas,while medium-sized and large juveniles preferred oceanic areas. The estimated d15N values (9.5–19.0‰) suggest that P.glauca is a top predator that occupies various trophic levels and/or it feeds across areas with different baseline d15N (trophicposition 3.9–8.4). Isotopic enrichment and differences in d13C and d15N thus suggest ontogenetic changes in habitat use andprey consumption between maturity stages. The use of hard anatomical structures (vertebrae) is highly relevant because theyintegrate information on the dietary ontogeny of this shark species.

Palabras clave: ontogeny; blue sharks; Isotopic enrichment

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