Trophic ecology of juvenile smooth hammerhead shark Sphyrna zygaena

Jan 28

Written By Karina Busto

Trophic ecology of juvenile smooth hammerhead shark Sphyrna zygaena (Carcharhiniformes: Sphyrnidae) in the central Gulf of California, Mexico

Mariana Alejandra Vázquez-Liñero | Felipe Galván-Magaña | Arturo Tripp-Valdez | Alberto Sánchez-González | Sergio Alejandro Briones-Hernández | Edgar Mauricio Hoyos-Padilla | Alejandra Piñón-Gimate

Environmental Biology of Fishes (2025)

DOI: https://doi.org/10.1007/s10641-024-01665-5

Abstract

The smooth hammerhead shark (Sphyrna zygaena) is an important component of the marine food web. However, information regarding its trophic ecology in the Central Gulf of California, Mexico, is scarce. This study aimed to describe the trophic ecology of juveniles of S. zygaena through stomach content and stable isotope analyses. From 2018 to 2019, 60 sharks were collected from local fishermen. Sizes ranged from 99 to 186 cm in total length. The stomach contents included 21 prey items, where the most essential prey were the squids Dosidicus gigas and Ancistrocheirus lesueurii and the fishes Scomber japonicus and Engraulis mordax according to the %PSIRI. Conversely, squids contributed the most to the diet according to the stable isotope-based mixing models. No significant differences in diet were found between sexes or sizes. The mean δ15N value was 21.2 ± 0.6‰ and − 15.8 ± 0.4‰ for δ13C, indicating coastal feeding habits representative of isoscapes from the Gulf of California. The Levin index showed that the juveniles of this species are specialist predators (0.2). The trophic position based on stomach contents (4.5) and stable isotopes (4.8) confirmed that juveniles of S. zygaena from the Central Gulf of California are at a high trophic level. Future studies are required to assess these observations further including adults.

Keywords

Stable isotopes, Feeding habits, Stomach contents, Mixing models

Karina Busto