| The trophic niche of the sympatric predators Pontoporia blainvillei(franciscana dolphin) and Trichiurus lepturus (ribbonfish) was compared by stable isotope (δ15N and δ13C) ratios in hepatic and muscular tissues to understand how they co-exist in the northern Rio de Janeiro State (21°30′S-22°15′S), south-eastern Brazil. Dolphin specimens were incidentally captured through commercial gillnet fisheries, while fish specimens were the target of these fisheries. The predators had similar δ15N values in the liver (P. blainvillei: 14.6 ± 1.0‰; T. lepturus: 14.4 ± 0.6‰), which indicates similar trophic position in the recent food intake. However,P. blainvillei showed lighter δ15N values in muscle (13.8 ± 1.0‰) than T. lepturus (15.0 ± 0.4‰), revealing differences... |
