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Journal article
Selective feeding of Southern Bluefin Tuna (Thunnus maccoyii) larvae on appendicularians in their eastern Indian Ocean spawning region
Deep-sea research. Part II, Topical studies in oceanography, Vol.226, 105591
2026
Abstract
We investigated ontogenetic variability in feeding and prey selection by Southern Bluefin Tuna larvae (SBT; Thunnus maccoyii) in their only global spawning region, located in the eastern Indian Ocean between northwestern Australia and Indonesia. Zooplankton prey and SBT larvae were sampled during four multi-day Lagrangian experiments conducted in the southern Argo Basin during the peak midsummer spawning season in January–February 2022. The zooplankton were identified, enumerated, sizes measured, and their developmental stages ascertained both in situ and from the stomach contents of the larvae. Larval stomach contents revealed high feeding incidence of 95 % with at least one prey item ingested with an average of 3.9 zooplankton prey per larva. Diet and prey selection transitioned during larval ontogeny from copepod nauplii to calanoid and corycaeid copepodites, and ultimately to cladocerans, as well as fish larvae when these were available. However, for all developmental stages and experiments, appendicularians stood out as the most significant prey taxon, constituting an average of 57 % of prey carbon biomass consumed and up to 79 % for postflexion stages. We observed some indication of increasing selection for appendicularians and fish larvae where they were most abundant, even when other suitable prey items were more readily available. Our study documents unprecedented high feeding incidence and positive selection for appendicularians compared to previous investigations of bluefin species, highlighting a pathway that enhances food web transfer efficiency. Appendicularians are uniquely able to thrive in oligotrophic environments and could be an optimal food source supporting SBT larvae in the future ocean.
Details
- Title
- Selective feeding of Southern Bluefin Tuna (Thunnus maccoyii) larvae on appendicularians in their eastern Indian Ocean spawning region
- Authors/Creators
- Rasmus Swalethorp - Scripps Institution of OceanographyEstrella Malca - University of MiamiAkihiro Shiroza - Instituto Español de OceanografíaLindsey Kim - Scripps Institution of OceanographyMoira Decima - Scripps Institution of OceanographyJosé M. Quintanilla - Instituto Español de OceanografíaRicardo Borrego-Santos - Instituto Español de OceanografíaClaire H. Davies - CSIRO Oceans and AtmosphereDavid Die - University of MiamiLynnath E. Beckley - Murdoch UniversityClaudia Traboni - Stazione Zoologica Anton DohrnGrace F. Cawley - Scripps Institution of OceanographyKamran Walsh - Scripps Institution of OceanographyMichael R. Landry - Scripps Institution of OceanographyRaúl Laiz-Carrión - Instituto Español de Oceanografía
- Publication Details
- Deep-sea research. Part II, Topical studies in oceanography, Vol.226, 105591
- Publisher
- Elsevier Ltd.; OXFORD
- Number of pages
- 14
- Identifiers
- 991005850984507891
- Copyright
- © 2026 The Authors.
- Murdoch Affiliation
- Centre for Sustainable Aquatic Ecosystems
- Language
- English
- Resource Type
- Journal article
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