DIET OF OCTOPUS BIMACULATUS VERRIL, 1883 (CEPHALOPODA: OCTOPODIDAE) IN BAHIA DE LOS ANGELES, GULF OF CALIFORNIA

Two hundred sixty-one octopuses were obtained from August 2006 to June 2007 in Bahia de Los Angeles, BC, Mexico. Sizes ranged from 58-190 mm in mantle length. Diet was determined from 3 sources: the digestive tract analysis (hard rests), accumulations of hard prey remaining in refuges, and live prey present during capture. Ripe females had the greatest fullness weight index (FWI) whereas spawning/spent females had the lowest. During the spring, female and male octopuses showed the greatest FWI, whereas in summer they showed the lowest, coinciding with the spawning/spent stage. A total of 76 prey items from 8 phyla were found, with Mollusca being the most important phylum and xanthid crabs the most important prey year-round. During autumn and winter, more bivalves were consumed, whereas more crabs were consumed in spring. Males fed mainly on crabs during all gonad development stages, but spent males fed mostly on molluscs. In contrast, females fed mostly on molluscs, except ripe females, which included more crabs in their diet. The octopus Octopus bimaculatus appears to be a specialist consumer, and this selectivity could be a consequence of different energetic demands of each sex during the gonad ripening process.