Resumen del producto

This study examines swordfish feeding habits through two complementary techniques: analysis of stomach contents (244 samples) and stable isotopes analysis (d¹³C) and (d¹⁵N) (128) samples, from specimens caught by the longline fleet. Thirty different prey types were identified. Based on the index of relative importance (IRI) cephalopods contributed 99.2%, fish 0.67% and pelagic crustaceans 0.1%; being the jumbo squid, Dosidicus gigas the most representative prey item (%IRI = 95.6). The similarity analysis showed no differences in the swordfish diet between years, sizes and sexes. Due to the predominance of D. gigas, the Levin index value classified this species as a specialist predator (Bi < 0.03). The stable isotope analysis showed d¹⁵N values between 13.05‰ to 19.66‰, and d¹³C values between -19.32‰ to -15.60‰ (µ = -17.50‰ ± 0.54‰); indicating that the swordfish feeds primarily on oceanic species. The isotope mixing models established that the prey species that most contribute to the diet were D. gigas and the mackerel Scomber japonicus, which coincides with observations through the traditional method; therefore, it is possible to infer that, within a period of 2 to 3 months, these prey species remain as the primary food items in the swordfish diet.

Palabras clave: Guadalupe fur seal; stomach content; diet

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