More on population structures along the coast of Mozambique
Seven breeding stocks, A to G, have been designated by the International Whaling Commission (IWC) to populations ranging from the western South Atlantic, eastwards to the eastern South Pacific (Cerchio et al., 2008). Breeding stock B seems to be isolated to the inter-oceanic breeding grounds of the southeast Atlantic, whereas breeding stock C seems isolated to the southwest Indian Ocean (Banks et al., 2010). Surveys have been conducted using photo ID as well as genetic microsatellites; both breeding stocks have been sub-divided according to genetic exchange and inter-regional sightings of individuals. Banks et al. (2010) used photo ID catalogues to compare humpback whale distribution and migration routes in the Mozambique area. Their results suggested that there are central and Southern Mozambique breeding grounds and a northern migration corridor.
Breeding stock C is the population that over winters in the western Indian Ocean, with a winter distribution ranging from the east coast of South Africa to Kenya (Cerchio et al., 2008). This breeding stock has been further subdivided into sub-populations C1, C2 and C3 based on the different sub-regions they occur (Best et al., 1998). C1 winters off the east coast of South Africa to Mozambique; C2 potentially migrates up the Mozambique Channel to winter grounds in the Comoros Archipelago; and C3 winters in the coastal waters of Madagascar (Best et al., 1997, 1998; Rosenbaum et al., 1997).
Past surveys were mainly conducted in cooperation with whale-watching companies. More structured research is needed to build a photo ID database for the southern coast of Mozambique in order to make intra- and inter-regional comparisons of individuals and to confirm the migration routes suggested. Ideally, data will be shared to enhance this progress as well as enlarging the area covered.