Work

Insights Into the Feeding Ecology of Young‐of‐the‐Year Bigeye Tuna ( Thunnus obesus ) in the Southwestern Atlantic Ocean

Year: 2025

Type: article

Abstract: ABSTRACT Bigeye tuna (Thunnus obesus) is among the most prized tuna species sustaining fisheries worldwide. However, information on the feeding habits for the species is mostly restricted to the size range harvested by commercial fisheries. In this study, we report the diet composition of juvenile bigeye tuna schooling near the surface at night in the oceanic area of the southwestern Atlantic Ocean. We combined short‐term dietary information derived from stomach content analysis (n = 14) with time‐integrated diet information from carbon (δ13C) and nitrogen (δ15N) stable isotope analysis (n = 8) to characterize diet composition and estimate trophic position (TPbulk) of the individuals. The prey‐specific index of relative importance (%PSIRI) indicated that Teleostei (79.1%) was the most important taxon, followed by Cephalopoda (7.6%) and Crustacea (3.9%). Myctophidae was the most frequent Teleostei in the diet (frequency of occurrence: 85.7%). The δ13C values on juvenile tuna muscle tissue ranged from −18.6‰ to −17.4‰ (mean ± SD: −18.1 ± 0.5‰) and δ15N values ranged from 7.2‰ to 8.4‰ (mean ± SD: 7.8 ± 0.3‰). TPbulk (4.15 ± 0.47) results corroborated a diet based on lanternfishes and the predation upon relatively small‐sized oceanic squids. Our results address a knowledge gap by highlighting important trophic links for bigeye tuna before they reach a size suitable for exploitation.

Source: Fisheries Oceanography

DOI: 10.1111/fog.12742

Authors: Juliano Lauser Coletto, Stefan Cruz Weigert, José Henrique Muelbert, Juliana Couto Di Tullio, Eduardo Resende Secchi, Silvina Botta

Institution: Universidade Federal do Rio Grande

Language: English

Topic: Isotope Analysis in Ecology

Subfield: Ecology

Field: Environmental Science

Domain: Physical Sciences

SDG: Life below water

Open Access status: hybrid

Estimated APC paid: $4,650