Finless porpoises (Neophocaena asiaeorientalis) in the East China Sea: insights into feeding habits using morphological, molecular, and stable isotopic techniques

Describing feeding habits of cetaceans is crucial to understanding their feeding strategies and conservation status. Here, both morphological and molecular techniques were employed to identify the stomach contents of 122 finless porpoises (Neophocaena spp.) in the East China Sea for insight into their short-term feeding habits, and stable isotopes of δ13C and δ15N were used to analyze prey resource use and trophic position as a manifestation of their long-term feeding habits. In total, 33 prey species consisting of 19 teleosts, seven crustaceans, five cephalopods, and two gastropods were identified. In both short- and long-term analyses, teleosts represented primary prey, cephalopods and crustaceans were secondary prey, and gastropods were occasional prey; but the primary prey species composition differs between the short- and long-term diets. The composition of stomach contents showed sexual and age-related variation. This finding is supported by stable isotopic analyses, which indicated the separation of trophic position of adult males, adult females, and young males. In general, finless porpoises prey on species that are primarily caught by fisheries.