Wallis and Futuna IMMA

Criterion A – Species or Population Vulnerability

Sperm whale occurrence in the waters of Wallis and Futuna seems ancient, with probable passage of whalers. The lack of effort, the small size of the islands among this large area of open waters could explain the small amount of evidence of their occurrence, with only two individuals observed during the REMMOA survey (Van Canneyt et al, 2015) and one stranding in 2015 (Service de environment Wallis and Futuna, pers.com). Sperm whales are classified as Vulnerable on the IUCN red list.

The sighting of humpback whales denotes the use of these waters by individuals belonging to the Oceania subpopulation (classified as Endangered by IUCN, Childerhouse et al. 2009).

Criterion B: Distribution and Abundance

Sub-criterion B2: Aggregations

Important species recorded in relatively high numbers in this IMMA include Longman’s beaked whales (Indopacetus pacificus) one of the world’s most poorly known whales.  During surveys six groups were encountered on effort, widely distributed in the area, totalling 21 individuals, plus four individuals encountered during off effort transit. Cuvier’s beaked whale (Ziphius cavirostris) was previously reported from boat surveys in the area (Doremus et al., 2010) and identified from a stranding in December 2012, and a Blainville’s beaked whale (Mesoplodon densirostris) was stranded in 2019 (Service de environment Wallis and Futuna, pers.com).

Melon-headed whales or possible pygmy killer whales (identification not confirmed) were estimated using Conventional Distance Sampling (without availability and perception bias correction) over the entire EEZ as tens of thousands of individuals (95%CI: 1600 – 53,000) with estimated group sizes of 1 – 200 individuals (Laran et al., 2016). Pantropical spotted dolphins and spinner dolphins were estimated at ~10,000 individuals (95%CI: 2500-37,000) and mainly distributed in the north of the IMMA. Common bottlenose dolphins (and possible unidentified rough-toothed or Fraser’s dolphins) were estimated at 4,200 individuals (800- 23,000) and mainly distributed west of Futuna Island in the shallowest waters, but rough-toothed dolphins were only identified once. About 2,000 Risso’s dolphins (95%CI: 2000-15,500) were estimated, and 800 (95%CI: 200-3000) short-finned pilot whale, false killer whale, and killer whales (only seen once). Several hundreds of beaked whales were estimated. Pygmy or dwarf sperm whales were encountered between 12°S and 14°S of latitude, with a relative abundance (uncorrected for bias) estimated at ~600 individuals (95%CI: 150-2100; Laran et al., 2016).

Criterion D: Special Attributes

Sub-criterion D2: Diversity

The Wallis and Futuna waters contains a remarkable diversity of cetaceans. A total of sixteen species have been confirmed in the area (Laran et al, submitted), with a quite broad distribution throughout the EEZ (Figure 2). Relative abundance was estimated for several species from the REMMOA survey and corrected for availability bias with a global cetacean abundance estimated to 0.18 individuals per km² and a good representation of small Delphininae (Stenella spp.), Globicephalinae subfamilies (Figure 4) a (Laran et al., 2023).