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Pacheco Aldana, P., S., Ortega García, L.A., Abitia Cárdenas, U., Jakes Cota, A., Tripp Valdez & A., Preti (2024). The feeding habits of striped marlin (Kajikia audax) in Cabo San Lucas, Baja California Sur, in response to seasonal and ontogenic influences. 7th International Billfish Symposium. San Diego Cal., Estados Unidos de América, octubre 8 - 10, 2024, 55-56.

The feeding habits of striped marlin (Kajikia audax) in Cabo San Lucas, Baja California Sur, in response to seasonal and ontogenic influences

Pamela Pacheco Aldana 1, Sofía Ortega García 1, Leonardo Andrés Abitia Cárdenas 1, Ulianov Jakes Cota 1, Arturo Tripp Valdez 1 y Antonella Preti 2

1 Instituto Politécnico Nacional, Centro Interdisciplinario de Ciencias Marinas, Pesquerías y Biología Marina
2 Southwest Fisheries Science Center
The striped marlin (Kajikia audax) is economically significant globally and important for recreational fishing in Cabo San Lucas, B.C.S., Mexico. Previous studies have described its trophic ecology using stomach content or stable isotope analysis. This study combines both methods to characterize changes due to sex, ontogenic development (juveniles and adults), and season (warm and cold). Stomach and muscle samples were collected from the Cabo San Lucas sportfishing fleet from 2019 to 2022.To date, 275 stomachs have been successfully analyzed, with 227 (83%) containing prey items. Organism lengths range from 140 cm to 242 cm. There are 82 prey items currently reflected in the diet. Preliminary results from the Prey Specific Index of Importance (%PSIRI) indicate that fishes dominate the diet, followed closely by Cephalopods. The most important species overall are Humboldt squid Dosidicus gigas (13.7%), Argonauta spp. (13.4%), Pacific Mackerel Scomber japonicus (8.3%), Balistes polylepis (7.5%) and Auxis spp. (5.76%).Female marlins mainly consumed D. gigas (16%), Argonauta spp. (15.5%), S. japonicus (7.7%), Fistularia spp. (7.67%), and B. polylepis (5.38%). Males primarily consumed Argonauta spp. (12.5%), D. gigas (12.2%), S. japonicus (8.63%), B. polylepis (8.54%), and Lagocephalus lagocephalus (7.1%). Juveniles (males =188 cm, females =197 cm) principally consumed Argonauta spp. (14.3%), D. gigas (14.3%), B. polylepis (7.9%), Fistularia spp. (6.6%), and S. japonicus (6.4%). Adults (males =189 cm, females =198 cm) primarily consumed S. japonicus (14.3%), D. gigas (12.2%), Argonauta spp. (11.8%), L lagocephalus (5.94%), and B. polylepis (4.93%) Diet varied by season: warm season diet included D. gigas (14.5%), Argonauta spp. (10.9%), B. polylepis (7.7%), Auxis spp. (7.6%), and L. lagocephalus (6.3%), while cool season diet included Argonauta spp. (18.8%), S. japonicus (18.1%), D. gigas (12%), S. sagax (11%), and Fistularia spp. (4.7%). The warm and cool seasons had significantly different diets (R = 0.103, p = 0.01), with no significant changes in other categories.Statistical analysis and interpretation of stable isotope data are currently in progress. The University of California Davis Stable Isotope Facility processed 80 muscle samples, and the final report was received in early June. Preliminary conclusions suggest striped marlins pursue similar prey regardless of sex and maturity, with prey availability fluctuating seasonally due to environmental conditions.

Palabras clave: Striped marlin; diet; Ontogenic variation; seasonal variation

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