Alimentación y relaciones tróficas del pez espada (Xiphias gladius Linnaeus, 1758), frente a Chile centro-norte durante 2005

A total of 126 swordfish (Xiphias gladius) stomach were analyzed. The stomachs were obtained from specimens captured within the 25° to 34°S and 78° to 90°W area, by industrial longline vessels. Only 72 (57.1%) of the total stomach had food items in their stomachs, whit a sex proportion of 32 males (44.4%), 37 females (51.4%) and 3 indeterminate (4.2%). Traditional methods for the stomach contents analysis such as the numeric, frequency of occurrence, gravimetric and index of relative importance (IRI) were used. Cephalopods were the main food items (%IRI>90) followed by the fishes (%IRI<4). The squid (Dosidicus gigas) was the principal food in this study (%IRI = 85.1). No significant differences were found between the feeding of males and females of swordfishes (U = 81; p = 0.4862, p<0.05). A cluster analysis showed higher stomach contents similarity between fall and winter than those from spring, within the size groups the I group was different than others and finally, the feeding from zone 3 were different from others zones.