MEPS 493:219-235 (2013)  -  DOI: https://doi.org/10.3354/meps10500

Diet of whale sharks Rhincodon typus inferred from stomach content and signature fatty acid analyses

Christoph A. Rohner1,2,3,*, Lydie I. E. Couturier1,4, Anthony J. Richardson1,5, Simon J. Pierce3,6, Clare E. M. Prebble3, Mark J. Gibbons7, Peter D. Nichols8

1Climate Adaptation Flagship, CSIRO Marine and Atmospheric Research, EcoScience Precinct, GPO Box 2583, Brisbane, Queensland 4102, Australia
2Biophysical Oceanography Group, School of Geography, Planning and Environmental Management, The University of Queensland, St Lucia, Queensland 4072, Australia
3Manta Ray and Whale Shark Research Centre, Marine Megafauna Foundation, Praia do Tofo, Inhambane, Mozambique
4School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia
5Centre for Applications in Natural Resource Mathematics (CARM), School of Mathematics and Physics, The University of Queensland, St Lucia, Queensland 4072, Australia
6Wild Me, Praia do Tofo, Inhambane, Mozambique
7Department of Biodiversity & Conservation Biology, University of the Western Cape, Bellville 7535, South Africa
8Wealth from Oceans Flagship, CSIRO Marine and Atmospheric Research, GPO Box 1538, Hobart, Tasmania 7000, Australia

ABSTRACT: Whale sharks Rhincodon typus are large filter-feeders that are frequently observed feeding in surface zooplankton patches at their tropical and subtropical coastal aggregation sites. Using signature fatty acid (FA) analyses from their subdermal connective tissue and stomach content analysis, we tested whether whale sharks in Mozambique and South Africa predominantly feed on these prey and/or what other prey they target. Arachidonic acid (20:4ω6; mean ± SD = 17.8 ± 2.0% of total FA), 18:0 and 18:1ω9c were major FA of whale sharks, while in contrast, coastal epipelagic zooplankton collected near feeding whale sharks had 22:6ω3 (docosahexaenoic acid), 16:0 and 20:5ω3 (eicosapentaenoic acid) as major FA. Stomach contents of 3 stranded sharks were dominated by mysids (61 to 92% of prey items), another one by sergestids (56%), and a fifth stomach was empty. The dominant mysids (82% index of relative importance) were demersal zooplankton that migrate into the water column at night, suggesting night-time feeding by whale sharks. High levels of bacterial FA in whale sharks (5.3 ± 1.4% TFA), indicating a detrital link, potentially via demersal zooplankton, also support night-time foraging activity. High levels of oleic acid (16.0 ± 2.5%) in whale sharks and their similarity with FA profiles of shrimp, mysids, copepods and myctophid fishes from the meso- and bathypelagic zone suggest that whale sharks also forage in deep-water. Our findings suggest that, in the patchy food environment of tropical systems, whale sharks forage in coastal waters during the day and night, and in oceanic waters on deep-water zooplankton and fishes during their long-distance movements.


KEY WORDS: Feeding ecology · Omega 6 fatty acids · Signature lipids · Mysida · Chondrichthyans · Fatty acid biomarkers


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Cite this article as: Rohner CA, Couturier LIE, Richardson AJ, Pierce SJ, Prebble CEM, Gibbons MJ, Nichols PD (2013) Diet of whale sharks Rhincodon typus inferred from stomach content and signature fatty acid analyses. Mar Ecol Prog Ser 493:219-235. https://doi.org/10.3354/meps10500

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