![]() Blue whales produce powerful and stereotyped songs, that they repeat in sequences for hours to days. To overcome the limitations of classical visual surveys, passive acoustic monitoring proves an efficient method to monitor this vocal species 4. ![]() In particular, little is known about the blue whales in the northern Indian Ocean 3. Despite their enormous size, blue whales have been difficult to observe in the Southern Hemisphere thus, for some regions, their population structure, distribution and migration routes remain poorly understood. Despite increases in blue whale populations at a global scale, their recovery remains slow and they are classified as Endangered by the IUCN Red List 2. The Indian Ocean holds a greater diversity of blue whale populations than thought previously.Ĭommercial whaling in the twentieth century brought blue whales ( Balaenoptera musculus) to the brink of extinction for instance, in the Southern Hemisphere it is estimated that less than 0.15% of the blue whale population survived whaling 1. Seasonal differences in song detections among our six recording sites suggest that the Chagos whales migrate from the eastern to western central Indian Ocean, around the Chagos Archipelago, then further east, up to the north of Western Australia, and possibly further north, as far as Sri Lanka. These songs are a large part of the underwater soundscape in the tropical Indian Ocean and have been so for nearly two decades. A comparison of this song with the pygmy blue and Omura’s whale songs shows that the Chagos song are likely produced by a distinct previously unknown pygmy blue whale population. ![]() Fortunately, blue whales produce powerful and stereotyped songs, which prove an effective clue for monitoring their different ‘acoustic populations.’ The DGD-Chagos song has been previously reported in the central Indian Ocean. ![]() Blue whales, although the largest animals on Earth, are difficult to study in the Southern Hemisphere, thus their population structure, distribution and migration remain poorly known. Blue whales were brought to the edge of extinction by commercial whaling in the twentieth century and their recovery rate in the Southern Hemisphere has been slow they remain endangered. ![]()
0 Comments
Leave a Reply. |