Diet of the Striped Dolphin, Stenella coeruleoalba, in the Eastern Tropical Pacific Ocean

Knowledge of the trophic ecology of pelagic dolphins is important to understanding the ecosystem of the eastern tropical Pacific. Mesopelagic species predominated in the diet of 131 striped dolphins; the myctophid Lampanyctus parvicauda, a melamphaeid Melamphaes sp., and the enoploteuthid squid Abraliopsis affinis were the most numerous and most prevalent. Composition varied among four regions; fish predominated in three southerly regions, and fish and cephalopods occurred in about equal numbers in a region close to the northern tropical convergence. Prey for which length could be estimated ranged from about 2 to 17 cm in length. Most feeding occurred at night or early in the morning. Species composition was similar to those for striped dolphins taken pelagically in other parts of the world in representing mainly mesopelagic species but differed from that for striped dolphins inhabiting more coastal regions, indicating flexibility in the trophic ecology of the species. The diet in the ETP resembled that of the pantropical spotted dolphin, S. attenuata, in the same region, although the latter may occasionally take larger prey. Overlap with the diet of the spinner dolphin, S. longirostris, in the same region is less; it may feed deeper, to 400m.