title: Stable isotopes indicate population structuring in the southwest Atlantic population of right whales (Eubalaena australis).
abstract: From the early 17th century to the 1970s southern right whales, Eubalaena australis, were subject to intense exploitation along the Atlantic coast of South America. Catches along this coast recorded by whalers originally formed a continuum from Brazil to Tierra del Fuego. Nevertheless, the recovery of the population has apparently occurred fragmentarily, and with two main areas of concentration, one off southern Brazil (Santa Catarina) and another off central Argentina (Peninsula Valdés). This pattern suggests some level of heterogeneity amongst the population, which is apparently contradicted by records that traced individuals moving throughout the whole geographical extension covered by the species in the Southwest Atlantic. To test the hypothesis of the potential occurrence of discrete subpopulations exploiting specific habitats, we investigated N, C and O isotopic values in 125 bone samples obtained from whaling factories operating in the early 1970s in southern Brazil (n=72) and from contemporary and more recent strandings occurring in central Argentina (n=53). Results indicated significant differences between the two sampling areas, being δ13C and δ18O values significantly higher in samples from southern Brazil than in those from central Argentina. This variation was consistent with isotopic baselines from the two areas, indicating the occurrence of some level of structure in the Southwest Atlantic right whale population and equally that whales more likely feed in areas commonly thought to exclusively serve as nursing grounds. Results aim at reconsidering of the units currently used in the management of the southern right whale in the Southwest Atlantic Ocean. In the context of the current die-off affecting the species in Peninsula Valdés, these results also highlight the necessity to better understand movements of individuals and precisely identify their feeding areas.
authors.affiliation: Department of Animal Biology and IRBio, Faculty of Biology, University of Barcelona, Barcelona, Spain.
authors.forename: Morgana
authors.initials: M
authors.lastname: Vighi
authors.affiliation: Department of Animal Biology and IRBio, Faculty of Biology, University of Barcelona, Barcelona, Spain.
authors.forename: Asunción
authors.initials: A
authors.lastname: Borrell
authors.affiliation: Laboratory of Marine Mammals, Centro Nacional Patagónico (CENPAT-CONICET), National University of Patagonia, Puerto Madryn, Argentina.
authors.forename: Enrique A
authors.initials: EA
authors.lastname: Crespo
authors.affiliation: University of Vale do Rio dos Sinos (UNISINOS), São Leopoldo, Brazil; Study Group of Aquatic Mammals of Rio Grande do Sul (GEMARS), Imbé, Brazil.
authors.forename: Larissa R
authors.initials: LR
authors.lastname: Oliveira
authors.affiliation: Department of Ecology and Zoology, Center of Biological Sciences, Federal University of Santa Catarina,Trindade, 88010-970 - Florianopolis, Santa Catarina, - Brazil.
authors.forename: Paulo C
authors.initials: PC
authors.lastname: Simões-Lopes
authors.affiliation: Centro Mamíferos Aquáticos - CMA (Centro Nacional de Pesquisa e Conservação de Mamíferos Aquáticos), ICMBio, MMA,, Jurerê Florianópolis, Santa Catarina, 88053-700, Brazil.
authors.forename: Paulo A C
authors.initials: PA
authors.lastname: Flores
authors.affiliation: Laboratory of Marine Mammals, Centro Nacional Patagónico (CENPAT-CONICET), National University of Patagonia, Puerto Madryn, Argentina.
authors.forename: Néstor A
authors.initials: NA
authors.lastname: García
authors.forename: Alex
authors.initials: A
authors.lastname: Aguilar
authors.affiliation: Department of Animal Biology and IRBio, Faculty of Biology, University of Barcelona, Barcelona, Spain.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Aguilar
mesh_terms: D000818:Animals; D001118:Argentina; D001267:Atlantic Ocean; D001842:Bone and Bones / Q000378:metabolism; D001938:Brazil; D002247:Carbon Isotopes / Q000378:metabolism; D009587:Nitrogen Isotopes / Q000378:metabolism; D010103:Oxygen Isotopes / Q000378:metabolism; D011157:Population Dynamics; D014907:Whales / Q000378:metabolism*
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D010103:Oxygen Isotopes