Seasonal and Geographic Variation of Southern Blue Whale Subspecies in the Indian Ocean

• Main Authors: Flore Samaran, Kathleen M. Stafford, Trevor A. Branch, Jason Gedamke, Jean-yves Royer, Robert P. Dziak, Christophe Guinet
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Antarctic; Indian; The Antarctic; Antarc*; Balaenoptera musculus; Blue whale
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.411.4645; http://hal.inria.fr/docs/00/85/57/76/PDF/Plos-one-Samaran-2013.pdf

Understanding the seasonal movements and distribution patterns of migratory species over ocean basin scales is vital for appropriate conservation and management measures. However, assessing populations over remote regions is challenging, particularly if they are rare. Blue whales (Balaenoptera musculus spp) are an endangered species found in the Southern and Indian Oceans. Here two recognized subspecies of blue whales and, based on passive acoustic monitoring, four ‘‘acoustic populations’ ’ occur. Three of these are pygmy blue whale (B.m. brevicauda) populations while the fourth is the Antarctic blue whale (B.m. intermedia). Past whaling catches have dramatically reduced their numbers but recent acoustic recordings show that these oceans are still important habitat for blue whales. Presently little is known about the seasonal movements and degree of overlap of these four populations, particularly in the central Indian Ocean. We examined the geographic and seasonal occurrence of different blue whale acoustic populations using one year of passive acoustic recording from three sites located at different latitudes in the Indian Ocean. The vocalizations of the different blue whale subspecies and acoustic populations were recorded seasonally in different regions. For some call types and locations, there was spatial and temporal overlap, particularly between Antarctic and different pygmy blue whale acoustic populations. Except on the southernmost