MOLECULAR IDENTIFICATION OF STRANDED RORQUALS IN THE NORTHERN COAST OF ARGENTINA CONFIRMS THE PRESENCE OF Balaenoptera brydei OLSEN 1913 IN THE SOUTH WESTERN ATLANTIC OCEAN

RODRÍGUEZ, DIEGO; MUÑOZ, GUILLERMO; GIARDINO, GISELA ; MANDIOLA, M. AGUSTINA; DASSIS, MARIELA; BASTIDA, JULIÁN; BASTIDA, RICARDO; WADA, SHIRO

Florianópolis (SC),

Congreso; XIV Reunião de Trabalho de Especialistas em Mamíferos Aquáticos da América do Sul (RT) 8º Congresso da Sociedade Latinoamericana de Especialistas em Mamíferos Aquáticos (SOLAMAC); 2010

SOLAMAC

Several factors make the identification of stranded rorquals (Cetacea: Balaenopteridae) particularlychallenging. The degree of decomposition and body position on the beach sometimes prevents ventralgroove count, colour identification or baleen inspection. Some body sizes overlap between maximum lengthsof intermediate species with medium sizes of big species. These factors result in most of the cases in a poorassignation of species. Molecular identification of rorqual species not only have increased the possibility ofspecies assignments, but also have proved successful in enlightening the Family taxonomy. Although sevenbalaenopterid species have been reported for the northern coast of Argentina, the strandings of thesewhales are very infrequent. In the last 6 years, three strandings have been reported in the area. The firstrorqual was a male (12.7m) stranded in Mar del Sur (August 2004), and provisionally identified as a seiwhale according to ventral grooves count. The second was another male (14.7m) stranded in Mar del Plata(April 2006), tentatively identified as a Bryde’s whale based on the presence of three rostral ridges. The thirdone was a 16.0m specimen stranded in Ensenada (April 2009) of unknown sex and unidentifiable species. Apartial cytochrome b gene (640 nucleotide sites from the beginning) was sequenced from skin samples ofthe three specimens, and compared with 8 Balaenoptera species retrieved from the GenBank. The analysisresulted in a positive identification of the three specimens as Balaenoptera borealis (Mar del Sur),Balaenoptera brydei (Mar del Plata) and Balaenoptera physalus (Ensenada). The number of differentnucleotides compared with published sequences was 3, 2 and 2, respectively. To reconfirm B.brydeiidentification, comparisons were made with an unpublished 416 bp Bryde´s whale control region sequencefrom the North Atlantic Ocean (DQ340979), resulting in a positive identification and a difference of 6nucleotides and 2 indels. The record of sei and fin whales in northern Argentina adds new records onexisting information, but this is the first confirmation of B.brydei inhabiting the southern SW Atlantic Ocean.Unavailable morphological diagnoses between edeni and brydei led to conservative assignation of B.edeni toall rorquals with three rostral ridges, leaving the correct species assignation unresolved. Our results confirmthe presence of Bryde’s whale in South America, but remains unclear if other morphologically identified“B.edeni” specimens in the region are in fact Bryde’s or Eden’s whales.