Boletín del Museo Nacional de Historia Natural, Chile 55: 51-60 (2006)

Avistamientos de ballenas azul balaenoptera musculus (linnaeus, 1758) y sei b. borealis lesson, 1828 en la costa nor - occidental de la isla de Chiloé, Chile

Ana Guzmán

Resumen

Se informa el avistamiento de ejemplares de ballena azul, Balaenoptera musculus, y ballena sei, B. borealis, en la costa nor-occidental de la isla de Chiloé, efectuados desde un punto preestablecido en Punta Caucaguapi (41º50?S - 74º03?W), entre el 29 de enero y el 27 de marzo de 2005. Se registraron 255 avistamientos de balaenoptéridos, de éstos, el 36,1% correspondieron a ballena azul y el 6,3% ballena sei; mientras que en el 57.6% de los avistamientos restantes no fue posible determinar las especies. Ambas especies avistadas fueron observadas alimentándose en el sector, actividad que representó el 86% y el 81% del total de los ejemplares avistados y determinados respectivamente. La presencia de ambas especies en el sector nor-occidental de la isla de Chiloé durante el verano permite plantear que la zona exterior de Chiloé constituye un área de alimentación de ambas especies.

Abstract

Sightings of blue whale, Balaenoptera musculus (Linnaeus, 1758) and sei whale, B. borealis Lesson, 1828 in the northwestern coast of Chiloé island, Chile. The sight of the blue whale, Balaenoptera musculus, and sei whale, B. borealis in the northwestern coast of the Chiloé Island is reported. Observations were carried out from a pre-established site that allowed the clearest cetaceans detection at Punta Caucaguapi (41º50?S - 74º03?W), since January the 29th until March the 27th, 2005. A total of 255 sights of balaenopterid whales were recorded. From them 36.1 % were blue whale sights; a 6.3% correspond to sei whales. In the remainder 57.6% of the sights it was not possible to identify the species. Feeding of both species in the area was observed and this activity oscillated between the 86% and the 81% from the total specimens saw and determined, respectively. The presence of both species in this north-western corner of the Isla de Chiloé through the summer allows to suggest that this area of the island represents an important place for the feeding of both species.