Humpback whale (Megaptera novaeangliae) post breeding dispersal and southward migration in the western Indian Ocean

Abstract

Investigating movement patterns of marine migratory species is critical to understand habitat use and population structure, and help inform conservation and management planning. Little is known about humpback whale (Megaptera novaeangliae) dispersal and migration in the western Indian Ocean. In October 2011 and 2012, eleven satellite transmitters were deployed on wintering humpback whales from the south-western Indian Ocean breeding stock at the Comoros islands (Mohéli, n=6 and Mayotte, n=5). Eight individuals were successfully tracked for 24.3±12.4days (range=8–49days) and travelled between 146km and 5804km in total. Whales either remained at their wintering site for several weeks (n=3) or dispersed along the west coast (n=4) or east (n=1) coast of Madagascar where two main stop-over sites were identified. In addition, two individuals travelled along straight paths to distant, potential, foraging areas. One whale reached the French sub-Antarctic islands while the other travelled to one of the supposed Antarctic foraging areas for humpback whales of this breeding stock. This is the first time movements of humpback whales from this area are being described and their potential foraging areas in the Southern Ocean identified. Identification of these dispersal patterns is important for delineation of breeding regions and for allocating abundance estimates to stocks.