Stable isotopic inferences on trophic ecology and habitat use of brown smooth-hound Mustelus henlei in the west coast of Baja California Sur, Mexico

The brown smoothhound shark Mustelus henlei is the most important shark species in the artisanal fisheries of the western coast of Baja California Sur, Mexico. Its trophic ecology was analyzed using carbon (¹³C) and nitrogen (¹⁵N) stable isotope analysis in the muscle tissue. The values of δ¹³C (−18.2 ± 0.6 ‰) and δ¹⁵N (17.7 ± 0.9 ‰) suggest that this species feeds in the Gulf of Ulloa throughout the year. The low values of δ¹³C indicate that the sharks feed in oceanic zones; while the δ¹⁵N values suggest that these sharks feed on prey that occupy a high trophic level and/or from a trophic chain with an enriched basal signal. The δ¹³C and δ¹⁵N values of this species do not present significant statistical differences between sexes and size. This study provides new insights regarding the habitat use of M. henlei, characterizing its preference for oceanic zones.