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

Type Article
Date 2013-08
Language English
Author(s) Samaran Flore1, 7, Stafford Kathleen M.2, Branch Trevor A.3, Gedamke Jason4, Royer Jean-YvesORCID5, Dziak Robert P.6, Guinet Christophe1, 7
Affiliation(s) 1 : Univ La Rochelle, Observ PELAGIS, CNRS, UMS 3462, La Rochelle, France.
2 : Univ Washington, Appl Phys Lab, Seattle, WA 98105 USA.
3 : Univ Washington, Sch Aquat & Fishery Sci, Seattle, WA 98195 USA.
4 : NOAA, Ocean Acoust Program, Off Sci & Technol, Natl Marine Fisheries Serv, Silver Spring, MD USA.
5 : Univ Brest, CNRS, Lab Domaines Ocean, UMR 6538, Plouzane, France.
6 : NOAA, Pacific Marine Environm Lab, Newport, OR USA.
7 : CNRS, Ctr Etud Biol Chize, UPR 1934, Villiers En Bois, France.
Source Plos One (1932-6203) (Public Library Science), 2013-08 , Vol. 8 , N. 8 , P. e71561
DOI 10.1371/journal.pone.0071561
WOS© Times Cited 77
Abstract 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 hydrophone, all three pygmy blue whale acoustic populations were found at different sites or during different seasons, which further suggests that these populations are generally geographically distinct. This unusual blue whale diversity in sub-Antarctic and sub-tropical waters indicates the importance of the area for blue whales in these former whaling grounds.
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