Killer whale / Orca (Orcinus orca)

Mohamed bin Zayed Species project number 10251290

This is an individual application, affiliated to the Mammal Research Institute (MRI) at the University of Pretoria. The MRI is dedicated to research and teaching on the biology and ecology of African/Southern Ocean mammals, including the conservation of indigenous mammal fauna in the context of sustainable human development. It was established in 1966 and has a distinguished history. The project (this application) entitled "Ecology of killer whales and their predatory impact on pinnipeds at Subantarctic Marion Island" falls within the MRI strategy of research, conservation and teaching. Long-term studies of killer whales have been conducted at various localities (Lopez & Lopez 1985, Bigg et al. 1990, Matkin et al. 1999). Based on behavioural, morphological and genetic evidence, a number of distinct populations have been identified, some occurring sympatrically (Morin et al. 2010). These populations specialize on certain prey types, mainly fish or, alternatively, marine mammals (Baird et al. 1992, Ford et al. 1998). Movement, behaviour and social system adaptations are linked to such dietary specialisation (Baird & Whitehead 2000). These studies, confined mainly to the northern hemisphere, have revealed a great deal of variation in the foraging ecology, behaviour, social structure and morphology in killer whales throughout their range and locally. In contrast, Southern Ocean killer whale studies are spatially and temporally limited, with the only (mostly punctuated) investigations other than at Marion Island, demonstrated at Peninsula Valdez, Îles Crozet, New Zealand and the southern Ross Sea. The conservation and indeed relatedness/similarity and thus species status of these killer whales remains unknown as a result of the limited research, despite their potentially critical role in ecosystem functioning (see Springer et al. 2003). Few locations in the Southern Ocean provide reliable and consistent sightings of the species to justify continued long-term monitoring. However, the limited published studies allude to significant behavioural and ecological differences between these killer whales (Guinet 1991; Hoelzel 1991; Tosh et al. 2008) and their northern hemisphere counterparts (e.g. Baird et al. 1992). Sustained long-term photo-identification and augmenting research (e.g. satellite telemetry, genetic analyses) would aid greatly in deciphering basic behavioural and biological aspects of killer whales around Subantarctic Marion Island. Such research will assist in gaining a greater understanding of the importance of killer whales as regulators of the local fauna and visa versa. Sustained presence of killer whales around Marion Island has provided a platform for opportunistic land-based studies there (de Bruyn 2010), but no dedicated, long-term studies have been implemented. This lack of knowledge of Marion Island (and generally for Southern Ocean) killer whales, and recent hypotheses pertaining to their predatory impact on seal populations have provided renewed impetus for long-term monitoring of this population. Furthermore, recent hypotheses proposing that the Marion Island killer whales hunt off South African shores (Williams et al. 2009) thereby potentially having an economic impact on fisheries activities requires validation. Without basic biological knowledge of this data deficient population of killer whales, their conservation status and their potential impact on vulnerable prey populations (Springer et al. 2003) cannot be assessed.