Sperm whales, the largest toothed predators on Earth, hunt squid in the deep water of the Ombai-Wetar Strait just off Dili. The strait drops to about 3,000 m within a short boat ride of the capital, and the main whale-watching season runs from October to December.
This post accompanies episode 6 of Scubazoo’s 2018 series Timor-Leste from Below.
Watch: episode 6
The sperm whale in brief
- Size: males reach about 16 m (52 ft) and 45 tonnes; females about 12 m (40 ft).
- Diet: mostly deep-water squid, plus fish, sharks and skates.
- Diving: dives routinely reach about 600 m and last around 45 minutes, followed by up to 10 minutes resting at the surface.
- Brain: the largest brain of any animal.
- Status: heavily reduced by commercial whaling until the International Whaling Commission’s moratorium took effect in 1986; still recovering.
Hunting by sound
A sperm whale’s huge, square head holds the spermaceti organ, which helps it produce and focus loud clicks. The whale uses these clicks to echolocate in the dark at depth: regular clicks while searching, speeding up into a rapid “creak” as it closes on prey. Sperm whales also communicate with patterned click sequences called codas. Researchers can follow hunting whales by listening with a directional hydrophone, as the Scubazoo team does in the episode.
Why the Ombai-Wetar Strait?
The Ombai-Wetar Strait, between mainland Timor and Atauro and Wetar islands, is part of the Indonesian Throughflow, the ocean current that carries water from the Pacific to the Indian Ocean. Its deep trough and strong currents bring food close to shore. Surveys led by marine ecologist Karen Edyvane since 2016 have recorded at least 21 whale and dolphin species in Timor-Leste’s waters, and the strait has been recognised as an Important Marine Mammal Area and, in 2020, a Mission Blue Hope Spot.
Planning a whale-watching trip
| Detail | Information |
|---|---|
| Best season | October to December (whale migration); dolphins year-round |
| Species | Pygmy blue whales, sperm whales, pilot whales and several dolphin species |
| Departure point | Dili, or Atauro Island |
| Sightings | Never guaranteed: these are wild animals in open ocean |
Trips are run by dive centres and boat operators in Dili and Atauro. Choose an operator that keeps its distance, approaches slowly from the side and limits time with each group of whales. See our dolphins and whales guide and dive operators. For the 2008 survey that first put the strait on the map, see whale and dolphin hotspot found off Timor-Leste.