Trophic ecology of Octopus mimus Gould 1852 and Dosidicus gigas d’Orbigny 1835 (Cephalopoda) in 2017

Abstract

Between February and December 2017, the diet composition was determined for the octopus (Octopus mimus) and jumbo flying squid (Dosidicus gigas). The study area for O. mimus included the islands located off the Callao Bay and off Ilo (Moquegua); for D. gigas, it covered the northern and southern areas in the summer (Cr. 1606-07) and spring (Cr. 1711-12) research cruises. The methods of frequency of occurrence (%FO), abundance (%N) and gravimetric (%P) were used to quantify the diet. In O. mimus, the modes of the fullness weight index (FWI) by seasons and mantle length (ML) were analyzed and in D. gigas, the analysis was based on fishing gear and area, sex, and length range (ML). In the octopus from Callao, the crustaceans Petrolisthes desmarestii and Synalpheus spinifrons stood out; in Ilo, S. spinifrons and Allopetrolisthes angulosus were predominant. No differences were observed in the FWI, by seasons and ML. In D. gigas from the summer cruise, the main prey (%P) were Vinciguerria lucetia (north), Pleuroncodes monodon (south) with differences in the FWI by fishing gear and area and ML; there were no differences by sex; in the winter cruise, D. gigas, other cephalopods (north), V. lucetia and myctophid fish (south) stood out. The influence of the El Niño Costero 2016-2017 on the feeding behavior of both cephalopods was observed.