548 shark species were considered in this paper. They were classified in function of their depth of occurrence: 218 deep, 114 transitory and 210 shallow. The diets of the 332 deep and transitory species are reviewed. 10 prey categories are recognized here: Chondrichthyes, Teleosts, Cephalopods, Crustaceans, Marine mammals, Annelids, Ctenophores, Egg of Chondrichthyes, Siphonophores, and Bivalves. There is a complete lack of data for 210 species, and 59 have only a limited amount of information available. In general, teleosts, crustaceans, and cephalopods were the main prey found in deep-water sharks. However, some species have a specialized diet. A simple index of dietary knowledge has been developed to highlight the current state of knowledge on the subject, further illustrating the lack of information. The proportion of empty and regurgitated stomachs varies significantly between species and studies. Most data on deep and transitory sharks come from stomach content analysis. Stable isotope analysis provides additional insight into their trophic ecology. Fatty acid profiling and DNA metabarcoding can also add important information, but their use is currently limited with deep-water sharks. The most important conclusion from this synthesis is the lack or scarcity of information for most deep and transitory species. |
