Vol 14 No 3 July 2015
Diet and trophic level of scalloped hammerhead shark (Sphyrna lewini) from the Gulf of California and Gulf of Tehuantepec, Mexico
Description:1-Instituto de Ciencias del Mar y Limnologia, Universidad Nacional Autónoma de México. Av. Joel Montes Camarena S/N Apartado Postal 811 C.P. 82040, Mazatlán, Sin. México 2-Istitute for Marine Resources and Ecosystem Studies Wagening UR Zuiderhaaks 5 1797 SH ’t Horntje, Texel, Netherlands. 3-Centro Interdisciplinario de Ciencias Marinas, Instituto Politécnico Nacional Av. IPN s/n Col. Playa Palo de Santa Rita. La Paz, B.C.S. C.P. 23096 México. *Corresponding author's email: yassirtorres@gmail.com
We examined the diet and trophic level ofSphyrna lewini in the Gulf of California (GC) during 2001 and in the Gulf of Tehuantepec (GT) during 2005 using data from stomach content and stable isotope analysis of δ15N and δ13C.S. lewini diet was represented by pelagic and benthic prey species where the most important in weight wasScomber japonicus (27.70±4.54%) in GC, while in GT it wasAuxis spp. (26.19±4.14%). There were differences for δ15N and δ13C between group sizes, showing a difference in the use of area and resources, while the differences for δ15N and δ13C between areas were related to changes in the isotopic signal from the base of the food web in each region. Based on δ13C and δ15N variability, diversity values (GC=3.69; GT=3.17) and diet breadth (GC=0.006; GT=0.002), we propose thatS. lewini is an opportunistic predator. The trophic level of
S. lewini was above four in all categories, which indicates thatS. lewini is a tertiary consumer. We may conclude thatS. lewiniplays an important functional role as top predator within areas of Mexico.

Keywords: Shark,Sphyrna lewini, Gulf of Tehuantepec, Mexico, Stomach content analysis, Stable isotopes.
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