Cephalopods in the Diet of Swordfish (Xiphias gladius) Caught off the West Coast of Baja California, Mexico

Abstract

The lower beaks of 1,318 cephalopods from the stomach contents of 175 swordfish, Xiphias gladius, caught off the west coast of Baja California, Mexico, between 1988 and In total, 20 species of teuthoids, 4 octopods, and one vampyromorph were identified. Weights and lengths of cephalopods were estimated from the lower rostral lengths. Ommastrephid squids, primarily jumbo squid Dosidicus gigas of different maturing sizes, composed 60% by number and 82% by estimated weight. Three species of gonatids were identified and represented 22% by number. An unidentified species of Argonauta was the most abundant octopod, with 5.8% of the beak total. Ancistrocheirus lesueurii is recorded for the first time in the California Current. Distribution of cephalopods in the California Current and their size in the diet of other marine predators are discussed. The diet of swordfish was dominated by medium to large muscular squid species that probably are eaten in surface waters at night. In fact, the study of cephalopod remains in the stomach contents of marine predators has contributed greatly to our knowledge of the distribution and ecology of these mollusks. Information on oceanic cephalopods in the diet of marine predators in the California Current and northeastern Pacific Ocean has come principally from studies on marine mammals, mainly odontocetes or toothed whales and pinnipeds.