Felipe GALVAN-MAGANA, Colombo ESTUPINAN-MONTANO, Jose Felix ESTUPINAN-ORTIZ, Luis German CEDENO-FIGUEROA, Carlos Julio POLO-SILVA

Diet of the bull shark, Carcharhinus leucas , and the tiger shark, Galeocerdo cuvier , in the eastern Pacific Ocean

This study presents information on the diet of two shark species,Carcharhinus leucasandGaleocerdo cuvier , that inhabit thesoutheastern Pacific Ocean. The stomachs were collected from October 2003 to July 2005 in Ecuador. Stomachs of 41C. leucasand sixG. cuvierwere analyzed. According to the index of relative importance (%IRI), the most important prey forC. leucaswere fishes: familyOphichthidae (13.41%),Tylosurus pacificus(9.79%),Katsuwonus pelamis(4.54%), and fish remains (44.81%).G. cuvier , for its part,consumed squids:Ancistrocheirus lesueuri(45.14%),Pholidoteuthis boschmaii(7.81%), andOctopoteuthisspp. (5.17%), as well as turtles:Caretta caretta(9.7%),Lepidochelys cf. kempii(5%), and turtle remains (16.5%). The results show thatC. leucas(trophic level,I TR ; 4.32 ±0.13) andG. cuvier( I TR ; 4.26 ± 0.09) are tertiary consumers, occupying high positions in the food chain, but also are generalist predatorsthat feed on a variety of prey. The high frequency of sea turtles in the stomachs ofG. cuvier(>300 cm) suggests that this shark species isan important predator of turtles, which are commonly found along the southeastern Pacific coasts.

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