Sightings of blue whale, Balaenoptera musculus (Linnaeus, 1758) and sei whale, B. borealis Lesson, 1828 in the northwestern coast of Chiloé island, Chile

Abstract

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.