Cabrera-Guerra, D., A., Tripp-Valdez, F., Galván-Magaña, A., Sánchez-González, F.R., Elorriaga-Verplancken, M.J., Zetina-Rejón & A., Delgado-Huertas (2025). Trophic ecology of Pacific sharpnose shark (Rhizoprionodon longurio) in Santa Rosalia, Gulf of California, Mexico. Environmental Biology of Fishes. 1-1-15-15. DOI: 10.1007/s10641-024-01660-w.
Delmis Cabrera-Guerra 1, Arturo Tripp-Valdez 2, Felipe Galván-Magaña 2, Alberto Sánchez-González 2, Fernando R. Elorriaga-Verplancken 2, Manuel J. Zetina-Rejón 2 y Antonio Delgado-Huertas 3
The Pacific sharpnose shark (Rhizoprionodon longurio) is an important species in the Baja California Sur fishery and is classified as “vulnerable” by the IUCN. Therefore, characterizing its trophic ecology by analysis of stomach contents and stable isotopes in muscle and vertebrae provides biological information for the implementation of management measures. From the fishing grounds of Santa Rosalia, 199 stomachs were examined, and in 166 muscle and 16 vertebrae samples, stable isotopes of carbon and nitrogen (d13C and d15N) were analyzed. Sixteen prey items were identified, and according to the Prey-Specific Relative Importance Index, the prey items that accounted for 80% of importance were the fish Calamus brachysomus (35%) and Merluccius productus (34%), the cephalopod Lolliguncula diomedeae (7%), and the crustaceans Caridea (3%) and Penaeus californiensis (2%). Preys with the highest isotopic contribution were M. productus (60.8%) and Mastigoteuthis dentata (30.9%), with a high overlap between sexes and intermediate between developmental stages. This suggests that the population shares food resources in Santa Rosalia. Furthermore, from the prey assemblage identified, the predator is demersal and pelagic in habits, performs vertical feeding movements, and particularly adult females explore a wider range of coastal and oceanic environments than males and juveniles. The shark R. longurio is an opportunistic meso-predator since it consumes the most abundant prey in its environment. However, juveniles and females were classified as generalists.
Palabras clave: Freshwater & Marine Ecology; Zoology; Animal Systematics/Taxonomy/Biogeography; Environment, general; Nature Conservation
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