Stomach content analysis of juvenile, scalloped hammerhead shark Sphyrna lewini captured off the coast of Mazatlán, Mexico

Abstract

We quantified the diet of juvenile, scalloped hammerhead shark Sphyrna lewini in the area off Mazatlan, Sinaloa, Mexico, to understand their feeding ecology this shark. The prey species of Sphyrna lewini were identified and quantified from stomach content analysis. In addition, we determined the variations between genders. During two fishing seasons (2000-2001 and 2001-2002), we analyzed 232 stomachs, of which 85% contained food. The trophic spectrum was composed of three species of cephalopods, six of crustaceans and 19 species of fish from mainly pelagic and benthic habitats. According to the Index of Relative Importance (%IRI), the cephalopod Loliolopsis diomedeae with IRI = 18%, fish of the family Carangidae IRI = 25% and family Synodontidae IRI = 19% constituted the main prey in general. The trophic niche width was \0.4, which indicated that S. lewini juveniles in this area feed on a wide range of prey items, though they showed a preference for a few prey items.

Trophic inference in two sympatric sharks, Sphyrna lewini and Carcharhinus falciformis (Elasmobranchii: Carcharhiniformes), based on stable isotope analysis at Malpelo Island, Colombia

“…Several studies about the trophic ecology of Sphyrna lewini report that this species feeds on cephalopods, fishes, rays, and crustaceans (Torres-Rojas et al 2006, Estupiñán-Montaño et al 2009, Torres-Rojas et al 2010, Zanella et al 2010, Galván-Magaña et al 2013, Torres-Rojas et al 2015. This species is considered as an important consumer of cephalopods in the eastern Pacific C compared with those offshore due to the influence of benthic primary production (France 1995, Tanaka et al 2008 or upwelling (Burton andKoch 1999, Graham et al 2010).…”

Fatty acids and stable isotopes as indicators of early-life feeding and potential maternal resource dependency in the bull shark Carcharhinus leucas

“…Mar Ecol Prog Ser 455: [245][246][247][248][249][250][251][252][253][254][255][256] 2012 man et , Torres-Rojas et al 2010, to molecular tools including stable isotope and lipid biomarker analysis (MacNeil et al 2005, Pethybridge et al 2010, Wai et al 2011. Although stomach content analysis can provide evidence for specific dietary items, biochemical approaches have the advantage of providing information on assimilated organic substrates and can be especially helpful in complex ecosystems with multiple organic carbon substrates (Dalsgaard et al 2003, Iverson et al 2004, Whiles et al 2010.…”

Ontogenetic migration of a female scalloped hammerhead shark Sphyrna lewini in the Gulf of California

“…Although males remain in shallow water until they reach a size of 160 cm TL, female hammerheads begin to migrate offshore sooner, at a length of 115 cm TL, to inhabit offshore seamounts and islands [13]. Current understanding of the ontogenic migration of the scalloped hammerhead shark in the Gulf of California is based largely on the incidental take of juveniles and stomach content analyses from a relatively small number of individuals [14,15]. Furthermore, the seasonal change in abundance of scalloped hammerhead shark landings by artisanal fishermen [16] and seasonal presence of large schools at volcanic islands and seamounts [14,17], suggest that this species migrates away from this region but returns to the same locations annually.…”