Toliara, St. Augustine Canyon and Anakao IMMA

Criterion A – Species or Population Vulnerability

Indian Ocean humpback dolphin (Sousa plumbea), IUCN Red List Endangered: A population resides in the near coastal habitat of this region, as documented by several studies (Andrianarivelo 2001, Razafindrakoto et al 2004, Van Canneyt et al. 2010, Cerchio et al. 2015). There is a history of extensive artisanal hunting and bycatch in local fisheries that has resulted in a documented decline in group size and encounter rate of groups and individuals (Andrianarivelo 2001, Razafindrakoto et al 2004, Cerchio et al. 2009, 2015). However, conservation efforts working with local villages to develop community-based protection mechanisms, outreach and education, and alternative-livelihoods to replace hunting, has resulted in the apparent cessation of hunting among the three main “Communes” (groups of villages) of the Anakao region (Cerchio et al. 2014, Andrianarivelo, personal communication). These conservation efforts are currently sustained by the presence of a community-based Association for the Protection of Whales and Dolphins (or in Malagasy, Fikambanana Miaro ny Trozona sy Fesotra, FMTF), consisting entirely of traditional Vezo fishers from the three participating Communes (Cerchio et al. 2014).

Criterion B: Distribution and Abundance

Sub-criterion B1: Small and Resident Populations 

Indian Ocean humpback dolphin, Sousa plumbea: The impacted small population, as described above, is likely resident in the area, although the extent of individual movements is unknown. Photographic identification data collected within the IMMA between 2004 and 2009, indicate relatively few individuals (almost certainly <50) with several re-sighted between years; at least one individual was sighted in four of the five years in which photographic data were collected (Cerchio et al. 2015, Cerchio and Andrianarivelo, unpublished data). Group size was relatively small compared to other areas with a mean of 3.6 individuals, and exhibited a declining trend from 2004 to 2013 (Cerchio et al. 2015).  Other regions in the southwest Indian Ocean have documented partially resident to highly resident populations, including Maputo Bay, Mozambique (Guissamulo & Cockcoft 2004), Richards Bay/KwaZulu-Natal coast, South Africa (Keith et al. 2002), and Zanzibar, Tanzania (Stensland et al. 2006). Sub-criterion B2: Aggregations

The St. Augustine submarine canyon supports notable aggregations of several deep water delphinids, including: short-finned pilot whales, Globicephala macrorhynchus – on several occasions, large groups have been documented in the Anakao and St. Augustine Canyon area, comprised of 2 or 3 subgroups of 20-40 individuals; Risso’s dolphins, Grampus griseus – the most commonly sighted oceanic delphinid during small boat-based surveys, found along the steep continental slope and canyon; Spinner dolphins, Stenella longirostris – regularly sighted along the shelf break and at times in large groups in excess of 500 individuals, often in association with  pantropical spotted dolphins (Stenella attenuata) along the edges of the canyon. 

Criterion C: Key Life Cycle Activities

Sub-criterion C1: Reproductive Areas

Humpback whale, Megaptera novaeangliae: The area is an active breeding area for humpback whales during July to October, with sightings continuing into December (Cerchio et al. 2009, Cerchio unpublished data, Cerchio et al. 2016, Trudelle et al. 2016). Breeding behaviour was regularly observed and satellite tracks of 11 whales tagged off Anakao indicated extensive movement through the boundaries of the IMMA and along the southern coast of Madagascar to Tôlanaro (Fort Dauphin), in the adjacent areas of Southern Madagascar.

Criterion D: Special Attributes

Sub-criterion D2: Diversity

High diversity with minimum 18 species documented: In addition to the species listed above, the following notable species are part of the diversity of the area: Southern right whale, Eubalaena australis – although this species is rarely sighted in the waters of Madagascar, there have been two documented sightings during boat surveys in the area, one of which was a mother-calf. In general right whales are sighted infrequently but regularly around Madagascar, with anecdotal sightings on both the west and east coasts (Rosenbaum et al. 2001, Cetamada unpublished data, Cerchio unpublished data). It is unclear whether these individuals represent range expansion from the South Africa population, or potentially represent remnants of an historical and near-extirpated population from Mozambique / Madagascar (Banks et al. 2011, Findlay personal communication), that was heavily hunted off the Crozet Islands (Townsend 1935); Common bottlenose dolphins, Tursiops truncatus – large offshore forms of bottlenose dolphins have been sighted on several occasions during boat surveys and aerial surveys (at times in association with pilot whales), and likely utilize the steep slope and canyon habitat; False killer whale, Pseudorca crassidens – sighted on several occasions during boat surveys and aerial surveys, and likely utilize the steep slope and canyon habitat; Sperm whale, Physeter macrocephalus – sighted on several occasions during aerial surveys and detected acoustically using dipping hydrophones during boat surveys and documented extensively during passive acoustic monitoring, and likely utilize the steep slope and canyon habitat.