Bintuni Bay, West Papua IMMA

Criterion A – Species or Population Vulnerability

The Australian humpback dolphin is listed as ‘Vulnerable’ by the IUCN and considered to be potentially declining throughout much of its range (Parra et al. 2017). The major threats are considered to be habitat loss and degradation, by-catch in fisheries, water pollution, underwater noise, floods and cumulative threats (Parra et al. 2017). West Papua represents the northwest extent of the species known distribution, with Australian humpback dolphins confirmed to occur in three locations in West Papua: Mayalibit Bay, Bintuni Bay and Kaimana Region. These regions comprise extensive mangrove, estuarine and coastal habitat particularly important for their survival. Bintuni Bay is notably important, as it represents one of the largest contiguous mangrove forests in the world. These habitats are subsequently important for the survival of Australian humpback dolphins in the region.

There are no known population or residency estimates for Australian humpback dolphins in Bintuni Bay. However, based on other known populations in northern Australia and southern Papua New Guinea, it is likely that the Australian humpback dolphin population in Bintuni Bay is relatively small and resident (Parra et al. 2018, Beasley et al. 2013, 2015). Bintuni Bay is one of only three regions in West Papua where humpback dolphins have been sighted, with no other Australian humpback dolphin sightings known for the region. As a result of the habitat characteristics of Bintuni Bay, it is proposed that aggregations of Australian humpback dolphins occur in the Bay, representing an important concentration for this species.

Criterion C: Key Life Cycle Activities

Sub-criterion C2: Feeding Areas

Bintuni Bay is a notably important feeding area, as it represents one of the largest contiguous mangrove forests in the world. As a result of this rich biodiversity and productivity, the region provides an important nutritional base on which many terrestrial and marine fauna species depend, particularly Australian humpback dolphins and other coastal dolphin species.

The known habitat preferences of Australian humpback dolphins are shallow and protected coastal habitats such as inlets, estuaries, shallow bays, inshore reefs and coastal archipelagos rather than in open stretches of coastline. In Queensland and Northern Territory, Australian humpback dolphins are mainly found in water less than 20 km from the nearest river mouth and in water less than 15-20 m deep (Parra et al. 2004, 2017). Few animals have been observed in waters up to 30-50 m deep but remained in close proximity (within 5 km) to the coast (Parra et al. 2004, 2017). In both Queensland and Northern Territory, Australian humpback dolphins have been also recorded as far as 20-50 km upstream in large rivers such as the East Alligator River, Northern Territory, and in the Fitzroy and Brisbane rivers in Queensland (Cagnazzi, 2010, Palmer et al. 2014, Parra et al. 2004). In Southern Papua New Guinea, Australian humpback dolphins were only found adjacent to delta/coastal mangroves, and no further than 2km from the coast (Beasley et al. 2013, 2015). Bintuni Bay therefore represents ideal habitat to support biological productivity and concentration of prey aggregations for marine mammals.