Diet components and trophic interactions in five demersal fish in CCAMLR Subarea 48.3

Diet components and trophic interactions in five demersal fish caught around of South Georgia’s waters was determined. Data were obtained from samples of Champsocephalus gunnari, Chaenocephalus aceratus, Pseudochaenichthys georgianus, Notothenia rossii and Dissostichus eleginoides, on a cruise carried out during the month of May 2013, on board of RV DY Eduardo L. Holmberg (INIDEP), at depths from 74 to 240 m. Prey Specific Index of Importance (%PSIRI) by each prey in each predator and, trophic level of all predators, was determined. Cluster Analysis was implemented based on diet components of all predators. Crustaceans were dominant prey group for C. gunnari and N. rossi, whereas C. aceratus and P. georgianus shows a diet where crustaceans and fishes had similar values of %PSIRI and D. eleginoides ate only fishes. Hyperiids and euphausiids were main prey among crustacean group. Demersal fishes identify as prey, were main prey for all analyzed predators, principally those to correspond to Channichthyidae and Nototheniidae families. All analyzed predators showed values of trophic levels that located as secondary level predators. Cluster analysis shows a grouping between C. gunnari and N.rossii, whose principal preys was hyperiids and mysids and close them, C. aceratus with zooplankton and fishes in similar proportions. Both D. eleginoides and P. georgianus, which not formed any group, shows diets mainly ichthyophagous and, in the case of P.georgianus, secondarily carcinophagous.