Feeding ecology of larval Bluefin Tuna in oligotrophic nurseries – selection for short efficient food chains
Food web architectures that support abundant high-quality prey within nursery habitats can be important for larval fishes to grow rapidly and successfully navigate their early life of fishes. Bluefin tuna species spawn in several oligotrophic regions of the world’s oceans that would seem poor choices for nursing larvae towards adulthood. So how do they fend off starvation and what mechanisms are in place to ensure that sufficient energy reaches the larval population? In this study, we investigated the diets, prey selections and trophic characteristics of larval Southern Bluefin Tuna (Thunnus maccoyii) and Atlantic Bluefin Tuna (Thunnus thynnus) in their Western Indian Ocean (IO) and Gulf of Mexico (GoM) spawning areas. Two cruises were carried out in the GoM (2017-18) and one in the IO (2022) where larvae and zooplankton were collected, identified in situ and in larval stomachs, and analyzed for stable isotopes. We found that larvae are highly selective for specific types of zooplankton prey, principally Appendicularia in the IO and Cladocera in the GoM. The characteristics of both prey types are high catchability and low trophic position relative to other zooplankton groups. High dietary contributions of these prey translate to faster growth and higher efficiency in energy transfer from the base of the food chain to the larvae. Our findings suggest a mechanism for maximizing growth and survival potential in low productivity spawning environments.
Presentation Preference: Oral
Primary Presenter: Rasmus Swalethorp, Scripps Institution of Oceanography (rswalethorp@ucsd.edu)
Authors:
Rasmus Swalethorp, Scripps Institution of Oceanography, UC San Diego (rswalethorp@ucsd.edu)
Estrella Malca, Cooperative Institute for Marine and Atmospheric Studies, Univ. Miami, USA (estrella.malca@noaa.gov)
Raul Laiz-Carrión, Centro Oceanográfico de Málaga, Instituto Español de Oceanografía (IEO-CSIC), Spain (raul.laiz@ieo.csic.es)
Akihiro Shiroza, Cooperative Institute for Marine and Atmospheric Studies, Univ. Miami, USA (a.shiroza@me.com)
Moira Decima, Scripps Institution of Oceanography, UC San Diego (mdecima@ucsd.edu)
José Quintanilla, Centro Oceanográfico de Málaga, Instituto Español de Oceanografía (IEO-CSIC), Spain (jose.quintanilla@ieo.csic.es)
Lindsey Kim, Scripps Institution of Oceanography, UC San Diego (lek001@ucsd.edu)
Ricardo Borrego-Santos, Centro Oceanográfico de Málaga, Instituto Español de Oceanografía (IEO-CSIC), Spain (ricardo.borrego@ieo.csic.es)
Claire Davies, CSIRO Oceans and Atmosphere, Castray Esplanade, Hobart, Tasmania, Australia (Claire.Davies@csiro.au)
David Die, Cooperative Institute for Marine and Atmospheric Studies, Univ. Miami, USA (ddie@rsmas.miami.edu)
Lynnath Beckley, Environmental and Conservation Sciences, Murdoch Univ., Murdoch, Western Australia (L.Beckley@murdoch.edu.au)
Claudia Traboni, Integrative Marine Ecology , Stazione Zoologica Anton Dohrn, Villa Comunale, Naples, Italy (claudia.traboni@gmail.com)
Grace Cawley, Scripps Institution of Oceanography, UC San Diego (gcawley@ucsd.edu)
Kamran Walsh, Scripps Institution of Oceanography, UC San Diego (kawalsh@ucsd.edu)
Michael Landry, Scripps Institution of Oceanography, UC San Diego (mlandry@ucsd.edu)
Feeding ecology of larval Bluefin Tuna in oligotrophic nurseries – selection for short efficient food chains
Category
Scientific Sessions > SS24 - Biogeochemistry and food webs of oligotrophic ocean regions and potential climate-change impacts on habitat quality for the larvae of large pelagic fishes
Description
Time: 03:00 PM
Date: 27/3/2025
Room: W201CD