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Marine Ecology Progress Series

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MEPS 734:91-104 (2024)  -  DOI:

Age validation of yellowfin tuna Thunnus albacares in the Indian Ocean using post-peak bomb radiocarbon chronologies

Igaratza Fraile1,*, Patricia L. Luque1, Steven E. Campana2, Jessica H. Farley3, Kyne Krusic-Golub4, Naomi Clear3, J. Paige Eveson3, Iraide Artetxe-Arrate1, Iker Zudaire1, Hilario Murua5, Gorka Merino1

1AZTI, Marine Research, Basque Research and Technology Alliance (BRTA), Pasaia, Gipuzkoa 20110, Spain
2Faculty of Life and Environmental Sciences, University of Iceland, Reykjavik 102, Iceland
3CSIRO Environment, Hobart, Tasmania 7000, Australia
4Fish Ageing Services, Queenscliff, Victoria 3225, Australia
5International Seafood Sustainability Foundation, 3706 Butler Street, Pittsburgh, PA 15201, USA
*Corresponding author:

ABSTRACT: Yellowfin tuna Thunnus albacares stock assessments use age-structured models; therefore, accurate methods for ageing the catch are required. Age estimation techniques need to be validated at the population level to ensure accuracy. However, otolith-based age estimates of yellowfin tuna have never been validated in the Indian Ocean. The current study provides the first age validation for Indian Ocean yellowfin tuna using the post-peak decline period of the bomb radiocarbon (14C) chronometer. A 14C reference chronology based on accelerator mass spectrometry assays of known-age yellowfin tuna otoliths was consistent with published regional coral records, with all showing similar rates of decline during the 2000 to 2019 study period. After back-calculating the birth years of sub-adult and adult yellowfin tuna from otolith increment counts, Δ14C values measured in the early growth portion of the otolith were compared with the observed decline slope of the reference chronology. There were no significant differences between the birth years of validation and reference samples, supporting the otolith increment age determination methodology between the ages of 2.2 and 10.5 yr. The validation of age and growth estimates is expected to benefit assessment models for Indian Ocean yellowfin tuna. We recommend that otoliths from large fish continue to be collected to expand the validation to older fish. Greater precision in the validation results will also require a larger reference chronology.

KEY WORDS: Bomb radiocarbon · Carbon-14 · Yellowfin tuna · Otolith chemistry · Age validation

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Cite this article as: Fraile I, Luque PL, Campana SE, Farley JH and others (2024) Age validation of yellowfin tuna Thunnus albacares in the Indian Ocean using post-peak bomb radiocarbon chronologies. Mar Ecol Prog Ser 734:91-104.

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