Southern Andaman Islands IMMA

Criterion A – Species or Population Vulnerability

The area is known habitat for a very small and vulnerable locally occurring population of dugongs (D’Souza et al. 2013; 2015). Stranded dugong calves and adults have also been recorded occasionally. Based on interview surveys with local fishermen, seagrass beds in this IMMA have been identified as ‘Critical Dugong Habitat of the Andamans’ (Sivakumar and Nair, 2013; D’Souza et al. 2013). Furthermore, dugong occupancy across this archipelago is estimated to have declined by 60% over the last 20 years and the present distribution is largely restricted to sheltered bays and channels supporting seagrass meadows dominated by Halophila and Halodule spp. (D’Souza et al. 2013).

Criterion C: Key Life Cycle Activities

Sub-criterion C1: Reproductive Areas

A total of 906 interviews were carried out in the Andaman and Nicobar islands (Sivakumar and Nair, 2013), of which 44% of respondents had sighted dugongs, with a total of 247 encounters reported. Of these 24% were of mother-calf pairs (Sivakumar and Nair, 2013) showing that the IMMA is an important reproductive area. Solitary individuals made up 60% of the observations. Dugong calves have been stranded in this region (www.marinemammals.in).

Indo-Pacific bottlenose dolphins were observed with calves and sub-adults in seven of the thirteen sightings between January and May 2018. The limited sampling effort restricts us from making remarks about reproductive seasons observed in the region but data collected suggests that the near-shore waters host resident populations of the species.

Sub-criterion C2: Feeding Areas

Indo-Pacific bottlenose dolphins have been observed foraging and feeding in near-shore waters.  The dolphins were seen feeding on Indian mackerel (Rastrelliger kanagurta) around reef habitats, and are also known to interact with shore seine nets that are used to catch bait fish species such as Sardinella sirm, Sardinella longiceps and Engraulis spp. suggesting that these near shore waters are important foraging grounds for the species. Dugongs are known to use the seagrass meadows in this IMMA and grazing trails were recorded in 11 seagrass meadows in this area (D’Souza et al. 2013; 2015). All feeding trails were recorded in meadows comprised of short-lived or early successional seagrasses like Halophila sp. and Halodule sp.

Criterion D: Special Attributes  

Sub-criterion D2: Diversity

Sixteen species of marine mammals have been documented from the waters of South Andaman making use of a diverse number of habitat types, from shallow coastal waters, offshore seas and complex undersea features, making this region critical (Mankeshwar and Sutaria, 2018; www.marinemammals.in). These include Indo-Pacific bottlenose dolphins (Tursiops aduncus), Dugong (Dugong dugon), Killer whales (Orcinus orca), False Killer whales (Pseudorca crassidens), Omura’s whale (Balaenoptera omurai), Fraser’s dolphins (Lagenodelphis hosei), Striped dolphins (Stenella longirostris), and Pantropical spotted dolphin (Stenella attenuata), Striped dolphin (Stenella coeruleoalba), Risso’s dolphin (Grampus griseus), Melon headed whale (Peponocephala electra), Short-finned pilot whale (Globicephala macrorhynchus), Longman’s beaked whale (Indopacetus pacificus), Cuvier’s beaked whale (Ziphius cavirostris), Dwarf sperm whale (Kogia sima), and Sperm whale (Physeter macrocephalus). The record of the Omura’s whale, which has been documented twice to date from within the IMMA, marks the northern record of the species in the Indian Ocean.