Trophic level and isotopic composition of 13C and 15N of pacific angel shark, Squatina californica (Ayres, 1859), in the Southern Gulf of California, Mexico

Abstract

δ13C and δ1NN stable isotopes were used to determine trophic level and the assimilated food components of Pacific angel shark, Squatina californica and its variation between size, sexes and seasonally in the southern Gulf of California, Mexico. Muscle tisúes were collected during 2001 to 2003. The quantification of δ13C and δ15N stable isotopes was realizad by isotope ratio mass spectrometry. The values of stable isotope of carbon (δ13C) ranged from -16.55 to -15.06% (average -15.94% + 0.34) and nitrógeno (δ15N) was between 18.30 to 19.52% (verage 18.90 + 0.27), we found that as male and female feeds on same zones and not differences were found years and seasons, therefore the angel shark present a same throphic level to feed on benthic prey in the coast zone. The trophic level was determined for S. californica with 4.5, therefore is considered a tertiary consumer in the Routh Gulf of California. We concluded that Pacific angel shark present a same trophic pattern Turing migration to deep areas in the Gulf of California, feeding on benthic species with same trophic level.