Trophic assessment and isotopic niche of three sympatric ray species of western Baja California Sur, Mexico

Along the Pacific coast of Baja California Sur (PCBCS), the banded guitarfish ( Zapteryx exasperata ), shovelnose guitarfish ( Pseudobatos productus ) and bat ray ( Myliobatis californica ) are highly abundant. Their ecological roles as predators in demersal communities can be key in this ecosystem. To better understand their trophic relationship in the PCBCS, stable isotopes analysis of carbon (ẟ 13 C) and nitrogen (ẟ 15 N) were used. Muscle samples ( n = 265) were collected from shovelnose guitarfish ( n = 94), banded guitarfish ( n = 87) and bat ray ( n = 84). We observed high variability in stable isotopes values, ẟ 13 C and ẟ 15 N of shovelnose guitarfish ranged from −18.53 to −12.85‰ and 15.93‰ to 20.37‰, respectively; banded guitarfish from −18.12‰ to −13.57‰ and 14.41‰ to 19.26‰, respectively; and bat ray from −17.73‰ to −13.98‰ and 13.97‰ to 18.46, respectively. Statistically significant interspecific differences were found ( p