TROPHIC INTERACTIONS AND GROWTH VARIABILITY OF TUNA LARVAE IN THE EASTERN INDIAN OCEAN BY STABLE ISOTOPE ANALYSIS

We examined early life trophic interactions of larval southern bluefin tuna (Thunnus maccoyii, SBT)  together with the co-occurring  albacore tuna (T. alalunga, ALB), and skipjack (Katsuwonus pelamis, SKJ) using stable isotope analysis. Larvae were collected during the BLOOFINZ-IO oceanographic survey (Jan–Mar 2022, part of the 2nd International Indian Ocean Expedition), from the only known SBT spawning ground. Species identification was based on morphology, meristic characters, pigmentation, and genetics. We  determined species trophic positions, isotopic niche widths and overlaps. Trophodynamic influences on larvae were assessed by contrasting environmental variables, daily growth, otolith biometry, and stable isotopes characteristics of post-flexion subpopulations of deficient vs. optimal growers. Trophic positions were similar among species. However, species differences in isotopic niche widths and overlaps suggest trophic resource partitioning with a mixture of competition and trophic differentiation that allow these species to share resources during their early life history. The results are discussed in terms of larval daily growth variability and compared with the larvae of other top predators in the region to evaluate species-specific distinctions. Understanding the growth-trophodynamics relationship is essential for identifying quality of the SBT nursery habitat in the oligotrophic spawning habitat of the Indian Ocean. This study was funded by INDITUN project PID2021/122862NB/100 (UE-FEDER) and BLOOFINZ-IO (USA-NSF). 

Presentation Preference: Oral

Primary Presenter: RAUL LAIZ-CARRION, Instituto Español de Oceanografia Ieo-Csic (raul.laiz@ieo.csic.es)

Authors:

Raúl Laiz-Carrión, Centro Oceanográfico de Málaga, Instituto Español de Oceanografía (IEO-CSIC), Spain.  (raul.laiz@ieo.csic.es)

Ricardo Borrego-Santos, Centro Oceanográfico de Málaga, Instituto Español de Oceanografía (IEO-CSIC), Spain / Departamento de Biología Animal, Facultad de Ciencias, Universidad de Málaga, Spain  (ricardo.borrego@ieo.csic.es)

José María Quintanilla, Centro Oceanográfico de Málaga, Instituto Español de Oceanografía (IEO-CSIC), Spain.  (jose.quintanilla@ieo.csic.es)

Francisco Abascal, Centro Oceanográfico de Canarias, Instituto Español de Oceanografía (IEO-CSIC), Spain  (francisco.abascal@ieo.csic.es)

Claudio Quezada- Romegialli, Plataforma de Monitoreo Genómico y Ambiental, Facultad de Ciencias, Universidad de Tarapacá, Chile.  (clquezada@ug.uchile.cl)

Estrella Malca, Southeast Fisheries Science Center, NOAA National Marine Fisheries Service. USA / Cooperative Institute for Marine and Atmospheric Studies, University of Miami. USA  (estrella.malca@noaa.gov)

Miguel Angel Godoy, Departamento de Biología Animal, Facultad de Ciencias, Universidad de Málaga, Spain  (miguelgb@uma.es)

Carolina Johnstone1, Centro Oceanográfico de Málaga, Instituto Español de Oceanografía (IEO-CSIC), Spain.  (carolina.johnstone@ieo.csic.es)

Rasmus Swalethorp, Scripps Institution of Oceanography, University of California San Diego, USA  (rswalethorp@ucsd.edu)

José Luis Varela, Departamento de Biología, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, Spain  (joseluis.varela@uca.es)

Manolo Vargas, Centro Oceanográfico de Málaga, Instituto Español de Oceanografía (IEO-CSIC), Spain.  (manolo.vargas@ieo.csic.es)

Isabel Riveiro, Centro Oceanográfico de Vigo, Instituto Español de Oceanografía (IEO-CSIC), Spain.  (isabel.riveiro@ieo.csic.es)

Pablo Abaunza, Centro Oceanográfico de Santander, Instituto Español de Oceanografía (IEO-CSIC), Spain.  (pablo.abaunza@ieo.csic.es)

Antonio Medina, Departamento de Biología, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, Spain  (antonio.medina@uca.es)

Miquel Planas, Instituto de Investigaciones Marinas (IIM-CSIC), Spain  (mplanas@iim.csic.es)

María Grazia Pennino, Centro Oceanográfico de Madrid, Instituto Español de Oceanografía (IEO-CSIC), Spain.  (grazia.pennino@ieo.csic.es)

David Die, 5 Southeast Fisheries Science Center, NOAA National Marine Fisheries Service. USA / Cooperative Institute for Marine and Atmospheric Studies, University of Miami. USA  (ddie@earth.miami.edu)

Trika Gerard, Southeast Fisheries Science Center, NOAA National Marine Fisheries Service. USA  (Trika.gerard@noaa.gov)

John Lamkin, Southeast Fisheries Science Center, NOAA National Marine Fisheries Service. USA  (j.lamkin@me.com)

Alberto García, Centro Oceanográfico de Málaga, Instituto Español de Oceanografía (IEO-CSIC), Spain.  (garaltomar@gmail.com)

Michael Landry, Scripps Institution of Oceanography, University of California San Diego, USA  (mlandry@ucsd.edu)