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Marine Ecology Progress Series

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MEPS 438:285-302 (2011)  -  DOI:

Foraging ecology of Mediterranean fin whales in a changing environment elucidated by satellite ­tracking and baleen plate stable isotopes

I. Bentaleb1,*, C. Martin1, M. Vrac2, B. Mate3, P. Mayzaud4, D. Siret5, R. de Stephanis6,7, C. Guinet8

1Université Montpellier II, CNRS-ISEM, UMR 5554, 34095 Montpellier, Cedex 5, France
2UMR 8212, Laboratoire des Sciences du Climat et de l’Environnement (LSCE-IPSL), CNRS-CEA-UVSQ, 91198 Gif Sur Yvette, France
3Marine Mammal Institute, Oregon State University, Newport, OR 97365, USA
4Laboratoire d'Océanographie de Villefranche, UMR CNRS 7093, BP. 28, 06230 Villefranche sur Mer, France
51 allée Louis de Villetain, 91190 Gif-sur-Yvette, France
6Department of Conservation Biology, Estación Biológica de Doñana, CSIC, C/Americo Vespucio, s/n, 41092, Isla de la Cartuja, Sevilla, Spain
7CIRCE, Conservation, Information and Research on Cetaceans, c/ Cabeza de Manzaneda 3, Algeciras-Pelayo, 11390 Cadiz, Spain
8Centre d’Etudes Biologiques de Chizé, 79360 Villiers-en-Bois, France

ABSTRACT: We investigated seasonal shifts in diet and distribution of fin whales Bala­en­optera physalus occurring in the western Mediterranean Sea. For this purpose, we combined carbon and nitrogen stable isotope ratios (δ13C, δ15N) along 10 baleen plates collected from stranded fin whales between 1975 and 2002 with satellite tag deployments on 11 fin whales during summer 2003. Baleen plate stable isotopes were compared with those of the krill Meganyctiphanes norvegica, the main prey of fin whales in the northwestern Mediterranean Sea. Two plates collected near Malaga, Spain, exhibited larger δ13C variations, while only smaller variations could be detected in the other 8. While all mean baleen plate results were consistent with the δ13C signature of Mediterranean M. norvegica, the most depleted δ13C values were intermediate between those of Atlantic and Mediterranean M. norvegica, suggesting westward migrations perhaps extending to the Strait of Gibraltar but not extensive, prolonged feeding in the Northeast Atlantic. This pattern was confirmed by satellite tracking; 1 out of 8 fin whales we successfully tracked left the Mediterranean for the Atlantic. Longer-term changes in isotopic signatures of baleen plates exhibited significant depletion trends, indicating that changes due to increasing input of nutrients and anthropogenic carbon are occurring in the western Mediterranean Sea ecosystem.

KEY WORDS: Meganyctiphanes norvegica · Mediterranean Sea · Foraging · Migration · Satellite telemetry · Environmental change

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Cite this article as: Bentaleb I, Martin C, Vrac M, Mate B and others (2011) Foraging ecology of Mediterranean fin whales in a changing environment elucidated by satellite ­tracking and baleen plate stable isotopes. Mar Ecol Prog Ser 438:285-302.

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