Diet of the barracuda Sphyraena guachancho in Cote d'Ivoire (Equatorial Eastern Atlantic Ocean)

The description of predator-prey interactions from trophic relationships are essential for understanding ecosystem functioning. We characterized and quantified the contribution of lower trophic levels in the diet of Sphyraena guachancho Cuvier, 1829, by season and size. Fish were sampled from commercial catches of the fishing port of Abidjan (Republic of Cote d'Ivoire, Equatorial Eastern Atlantic Ocean) between July 2010 and June 2011. A total of 318 specimens ranging from 19 to 63 cm fork length (FL) were examined. The vacuity index varied significantly between seasons with higher values in great cold season (71.3%), intermediate in the great and short dry seasons, 53.7% and 54.9%, reapectively, and lowest in low cold season (48.9%). A total of 12 families were found in the stomachs of S. guachancho, mainly teleost fish species (mostly Clupeidae, Sphyraenidae, Carangidae and Engraulidae). Index of relative importance (IRI) was calculated for prey items found in guts to characterize diet and consisted of fish (IRI = 70.9%), cephalopods (IRI = 16.7%) and crustaceans (IRI = 12.4%). The IRI trend was the same during the warm and cold seasons, with the exception of January-February period where cephalopods were the dominant prey (IRI = 81.3%). A hierarchical cluster analysis highlighted diet similarities between individuals from size groups 19-24 cm FL, 24-54 cm FL and 54-63 cm FL. However, the first and the last size groups ate only fish while the intermediate size group consumed all three food groups (fish, cephalopods and crustaceans), including conspecifics (cannibalism)