Abstract:
In order to examine the feeding of mako shark Isurus oxyrinchus, the stomach content of
205 specimens, captured between 21º and 35ºS and 78º and 118º W off Chile, during 2005 and 2006 were
analyzed. The 47.8% of the sharks had food in their stomachs. The numeric, frequency and weight
methods and the index of relative importance (IIR) were used to describe their diet. The diet was
compared between sexes and spatio-temporal variations of the diet were also determined. The diet of the
mako shark consisted of 17 prey items. Teleost fishes were the most important prey item (86.9% IIR),
followed by cephalopods (12.3% IIR). Other preys were in low frequency (<1% IIR) and they were
represented by elasmobranch fishes, marine birds and marine mammals. No differences in diet were found
between sexes of shortfin mako, however, it was detected variation between seasons and fishing zones.
According to its diet the mako shark is considered a generalist species.
Resumen: Con el objeto de examinar la alimentación de Isurus oxyrinchus (marrajo) se analizó el
contenido estomacal de 205 ejemplares, capturados entre los 21º y 35ºS - 78º y 118ºW, frente a las
costas de Chile, durante los años 2005 y 2006. El 47,8% de los estómagos presentó contenido. Para el
análisis de su dieta se utilizaron los métodos numéricos, de frecuencia, gravimétricos e índice de
importancia relativa (IIR). Se comparó la dieta entre sexos y se determinó si había variaciones
espacio-temporales. La dieta del marrajo consistió en 17 ítemes presa. Los peces óseos (86,9% IIR) fueron
las presas principales, seguidas por cefalópodos (12,3% IIR). El resto de las presas tuvo escasa
presencia (< 1% IIR) representada por elasmobranquios, aves y mamíferos marinos. El marrajo no presentó
diferencias dietarias entre sexos, pero sí se evidenciaron variaciones espacio-temporales. De acuerdo
a su dieta, el marrajo es una especie generalista.
