, Volume 47, Issue 2, pp 203-211

Ontogenetic dietary shifts and feeding behavior of the tiger shark, Galeocerdo cuvier , in Hawaiian waters

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Synopsis

Stomach content data from 281 tiger sharks caught during shark control programs in Hawaii between 1967 and 1969, and during 1976 were analyzed to examine feeding habits and ontogenetic shifts in diet. As sharks increased in size, prey diversity and frequency of occurrence of large prey items increased. The percent occurrence of teleosts and cephalopods in stomachs decreased as sharks increased in length, while occurrence of elasmobranchs, turtles, land mammals, crustaceans, and undigestible items increased. Comparisons between the diets of tiger sharks from Hawaii and other locations indicate that ontogenetic shifts are universal in this species and that tiger sharks may be opportunistic feeders that prey heavily on abundant, easy to capture prey. Small tiger sharks may be spatially segregated from medium and large sharks and appear to be primarily nocturnal, bottom feeders. Large tiger sharks feed near the bottom at night, but also feed at the surface during the day. Prey, similar in size to humans, begin to occur in the diet of tiger sharks approximately 230 cm TL, and therefore sharks of this size and larger may pose the greatest threat to humans. Ontogenetic shifts in diet may be attributed to increased size of sharks, expanded range and exploitation of habitats of larger sharks, and/or improved hunting skill of larger sharks.