Abstract:

Although bottlenose dolphins Tursiops truncatus are among the most common delphinid species, global population trends remain poorly understood. To improve the knowledge of the species in the Southwest Atlantic Ocean, this paper reviews all available data related to the distribution and occurrence, abundance, residency and ranging patterns, group size and composition, survival and reproduction and population structure of the coastal bottlenose dolphin in Argentina. Most information proved to be scattered in time and space. Based on the available data, total abundance of coastal bottlenose dolphins in Argentina appears to be low. Data show sightings decreased notably since the 1990s in the northern province of Buenos Aires and the province of Chubut, with the species having disappeared completely from the former region. Data also indicated that two genetically and morphologically distinct coastal populations occur in Argentinean coastal waters, with a sympatric distribution in the provinces of Río Negro and Chubut. One is an isolated ‘Evolutionary Signifcant Unit’ within the larger Southwest Atlantic, whereas the other population appears to be genetically related to the Southwest Atlantic offshore ecotype. In the absence of more substantial data, the present information is pertinent to our scientifc knowledge of the species in the country, collating all published information as well as information from grey literature and previously unpublished data. However, the available information appears to remain insufcient to explain the apparent decline in sightings and to assess the remaining abundance nationwide accurately. Therefore, we strongly recommend increased research efforts for an in-depth assessment of the species’ population status in Argentina.

Author affiliation: Vermeulen, Els. University of Pretoria. Mammal Research Institute Whale Unit; Sudáfrica. Whalefish; Reino Unido

Author affiliation: Bastida, Ricardo Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina

Author affiliation: Berninsone, Leonardo G.. Fundación Aqua Marina; Argentina. Universidad de Cádiz; España. Universidad de Algarve; Portugal

Author affiliation: Bordino, Pablo. Fundación Aqua Marina; Argentina

Author affiliation: Failla, Mauricio. Fundación Cethus; Argentina

Author affiliation: Fruet, Pedro. Universidade Federal do Rio Grande. Museu Oceanográfico “Prof. Eliézer de C. Rios”; Brasil. Kaosa; Brasil. Centro Nacional de Pesquisa e Conservação de Mamíferos Aquáticos; Brasil

Author affiliation: Harris, Guillermo. Wildlife Conservation Society; Estados Unidos

Author affiliation: Iñíguez, Miguel. Fundación Cethus; Argentina

Author affiliation: Marchesi, María Constanza. Museo Acatushún de Aves y Mamíferos Marinos Australes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina

Author affiliation: Petracci, Pablo. Universidad Nacional del Sur; Argentina

Author affiliation: Reyes, Laura. Universidad Nacional de la Patagonia. Facultad de Ciencias Naturales. Sede Puerto Madryn; Argentina

Author affiliation: Sironi, Mariano. Instituto de Conservación de Ballenas; Argentina. Universidad Nacional de Córdoba; Argentina

Author affiliation: Bräger, Stefan. International Seabed Authority; Jamaica

Abstract:

Como parte de un proyecto de relevamiento de aves marinas en el Atlántico Sudoccidental, se realizó una campaña en el Golfo San Matías, en la costa austral de Argentina, con el objetivo de evaluar la interacción de aves con la flota potera que tiene como especie objetivo al calamar argentino <i>Illex argentinus</i>. Entre el 7 y el 21 de julio de 2003 se observaron 20 especies de aves marinas pertenecientes a 6 familias. El 21 de julio, en 41°17'S, 64°36'W, un Petrel de Trinidade (<i>Pterodroma arminjoniana</i>) fue observado junto a 100 Thalassarche melanophris, 200 <i>Larus dominicanus</i>, 10 <i>Macronectes giganteus</i>, 20 <i>Oceanites oceanicus</i> y 10 <i>Procellaria aequinoctialis</i>. Se discuten algunos aspectos referidos a la identificación en el campo, taxonomía y conservación. A partir de datos y circunstancias del registro, se especula sobre la posibilidad de que aves errantes o quizás visitantes regulares subobservadas, puedan asociarse con la pesquería del calamar sobre la Plataforma Continental Argentina.

As part of a survey of marine birds in the Southwest Atlantic, a field trip was made to Golfo San Matías, on the coast of southern Argentina, to accomplish a first evaluation of seabirds associated with the Argentine squid <i>Illex argentinus</i> fishery by jiggers. Between 7–21 July 2003, 20 species of seabirds belonging to 6 families were observed. On July 21, at 41°17'S, 64°36'W, a Trinidade Petrel (<i>Pterodroma arminjoniana</i>) was observed along with 100 <i>Thalassarche melanophris</i>, 200 <i>Larus dominicanus</i>, 10 <i>Macronectes giganteus</i>, 20 <i>Oceanites oceanicus</i> and 10 <i>Procellaria aequinoctialis</i>. We discuss some aspects of field identification, taxonomy and conservation. The data and circumstances of our record allows us to speculate that it is possible that vagrant birds, or maybe sub-observed regular visitors, may be associated with the squid fishery on the Argentine continental shelf.