Diet and feeding ecology of the little tunny, Euthynnus alletteratus (Pisces: Scombridae) in the central Colombian Caribbean: changes in 18 years

Abstract

Trophic ecology and diet of the little tunny (Euthynnus alletteratus) in central Colombian Caribbean is described. The little tunny is a pelagic top predator but not a voracious fish (trophic level of 4.49, Q/B of 10.8). Its diet seems impoverished when compared with a study conducted in 1986 in the same general location and with studies in other locations. Moreover, the main diet item has changed, new items have appeared and other have disappeared in the time interval between 1986 and the present study (2003/2004, 18 years). Lack of monitoring of pelagic fish populations precludes the identification of tendencies but a regime change hypothesis is worth investigating. The little tunny eats more in the dry season than in the rainy season and diet items change with seasons in line with findings of other studies that signal correlations between seasons and diet. Likewise, local little tunny eats more in the afternoon than in the morning which suggests it eats in daylight not in the night contrary to what has been found in studies somewhere else.