Trophic habits of the Ommastrephid squid Illex coindetii and Todarodes sagittatus in the northwestern Mediterranean Sea

Squids Illex coindetii and Todarodes sagittatus were collected from commercial trawls in the NW Mediterranean Sea and their stomach contents were analyzed to describe and compare their feeding habits. Fish, crustaceans and squids were found in the stomach contents of both squid species; however T. sagittatus had a wider trophic spectrum composed by fifteen prey items more than I. coindetii. This difference was attributed to the availability of feeding resources in the water column and the larger size and deeper distribution of T. sagittatus. The index of relative importance showed that the crustacean Pasiphaea multidentata was the most important prey for both squids, and that I. coindetii fed secondly on Anchilomera blossevillei, Pasiphaea sivado and the fish Lestidiops sp., while T. sagittatus fed secondly on Phronima sedentaria and the fish Arctozenus risso. The feeding habits of the two squids varied for two prey items at the size interval between 9.1 and 21 cm ML. This difference was due to the presence of the amphipod P. sedentaria and the squid Ancistroteuthis lichtensteinii in the stomach contents of T. sagittatus, which are species with deeper distributions. T. sagittatus larger than 21 cm ML preyed on other crustaceans and fish, such as big Pandalidae crustaceans and gadiform fish. Finally, the %FO analysis showed that there were fifteen common prey species in the feeding habits of the two squids, but they did not have the same importance for each squid. I. coindetii fed mainly on Lestidiops sp., Chauliodus sloani and P. multidentata and T. sagittatus fed on A. risso and P. sedentaria. These species correspond to mesopelagic fish, decapod crustaceans and amphipods. This suggests that these species are easy to prey at different levels in the water column, which affects the predation and distribution of I. coindetii and T. sagittatus.