Feeding habits of the pantropical spotted dolphin, Stenella attenuata, off the Eastern coast of Taiwan

Stomach contents were analyzed from 45 pantropical spotted dolphins, Stenella attenuata, confiscated by Taiwan police and as by-catches by in fisheries off eastern Taiwan from February 1994 to November 1995. Mesopelagic prey species dominated the stomach contents. Sixty-four species of fish made up 67.5% and 21 species of cephalopods made up 32.5% by number. Myctophid lanternfishes and enoploteuthid squid accounted for 78.3% of all prey consumed. The enoploteuthid squid, Enoploteuthis chunii, was the primary prey and represented 25.8% by number of the total prey, with an overall occurrence of 66.7%. Results of this study are generally similar to those at earlier food habits studies conducted on this species in the eastern tropical Pacific. In both regions, the ratio of fish and cephalopods consumed and the trophic levels of the dominant prey were similar. Stenella attenuata in the eastern tropical Pacific and off the eastern coast of Taiwan are feeding primarily on myctophid lanternfishes and species of the cephalopod families Enoploteuthidae and Ommastrephidae. The ANOSIM analysis demonstrated a significant difference in prey composition by season. The most numerically abundant prey species, Enoploteuthis chunii, play an important role in the observed seasonal differences, which contributed 16.8% to the average dissimilarity between fall-winter and spring-summer.