Wetar Strait

A mangrove patch east of One Dollar Beach, East Timor, in 2013

The shallow coastal waters along the northern littoral of East Timor are dominated by a seagrass bed about 2,200 ha (5,400 acres) in total area.[11]^{: 2-29–2-30} Seagrass beds protect coral reefs from sedimentation and are feeding grounds for dugong (Dugong dugon), an endangered species.[12]^: 82 Seven genera of seagrass are known to exist off East Timor's coastline as a whole.[11]^: 2–29

East Timor's coastal waters have also traditionally hosted mangrove forests. Together with seagrasses and coral reefs, they are the primary breeding grounds for many species of fish and shellfish. However, the country's mangrove cover has very substantially declined since 1940, and in the Wetar Strait is now confined to the coastline and hinterland between Cape Fatucama and Manatuto.[12]^{: xvi, xvii, 3–5, 81, 82}[13]

At the strait's mangrove communities in Hera and Metinaro, East Timor, the latter of which is considered to be the largest mangrove area in the country, the dominant species are Sonneratia alba, Rhizophora apiculata, Ceriops tagal, and Avicennia. Uniquely, the landward zone of both areas is dominated by stunted dense Ceriops tagal or Avicennia, or a mix of the two. In general, the mangroves in both areas are heavily disturbed by human activities, including road and building construction, fish and shrimp ponds, uncontrolled cattle grazing, mangrove cutting, heavy sedimentation, and sea level rise. Both areas are therefore now far smaller than they used to be.[13]

Dolphins in the Banda Sea in 2017

Both Wetar Strait and Ombai Strait are heavily used by whales, dolphins, whale sharks and manta rays; the two straits combine to form a major migratory route for such marine life between the Indian Ocean and Pacific Ocean.[14] East Timor, on the south side of the two straits, is a recognized ‘global hotspot’ for whales and dolphins,[15][16] and Wetar Strait has been described by marine scientists as an ‘ocean superhighway’ for them. Amongst the species of whales and dolphins that migrate via the strait are blue whales, beaked whales, short-finned pilot whales, melon-headed whales, spotted dolphins, rough-toothed dolphins and bottlenose dolphins.[17]

Wetar Strait is also part of the Coral Triangle, which is recognised as a global centre of marine biodiversity;[18] the coastal zones of East Timor have important areas of coral reef ecosystems.[11]^{: 2-29–2-30}

The far north western end of the strait includes an Important Bird Area (IBA), Atauro Island.[19] The southern edge includes three IBAs. From west to east, they are Areia Branca no Dolok Oan (at the far western tip of the strait), Subaun (between Metinaro and Manatuto), and Mount Paitchau and Lake Iralalaro (at the far eastern tip of the strait).[20] The last of these IBAs covers almost the same territory as the Nino Konis Santana National Park, the first national park to be created in East Timor.[21]

On World Oceans Day 2020, the Ombai-Wetar Strait was designated as a Mission Blue Hope Spot. The designation recognises the importance of conserving the open waters on the north side of East Timor, with their globally-significant coral reefs and marine biodiversity. It also emphasises the potential of the two straits for sustainable marine ecotourism development.[22]

The Berlin-Ramelau prior to her launch in 2021

Under the United Nations Convention on the Law of the Sea, a commercial vessel or aircraft has freedom of navigation or overflight solely for the purpose of continuous and expeditious transit of a strait between one part of the high seas or exclusive economic zone and another.[23] That transit passage principle applies to the Ombai Strait and Wetar Strait, as they combine to link the Indian Ocean with the Pacific Ocean.[4][24]

The Ombai-Wetar route is longer in distance than its Strait of Malacca-Singapore Strait counterpart. The former route is therefore not really a preferred alternative path for west to east commercial traffic.[4] However, it is sometimes used, and is considered the safest route, for the largest oil tankers transiting between the Persian Gulf and Japan, and is also used by vessels transiting between Australia and the Java Sea or East Asia.[24]

The two straits are always critical for East Timor, both in relation to its own international trade and as routes for internal transport.[24] The Berlin-Ramelau operates internal East Timorese ferry services linking Dili with Manatuto, Baucau, Lautém and Viqueque via the Wetar Strait.[25][26]

If there were any disruption in the flow of commercial shipping on the Malacca-Singapore route, the Ombai-Wetar route would also have a crucial role to play in global trade, especially for the Asia-Pacific region.[24]

USS Cleveland near the transition between the two straits in 2011, with Cape Fatucama behind her

The ships and aircraft of all nations, including warships, auxiliaries, and military aircraft, enjoy the right of unimpeded transit passage through straits such as the Ombai-Wetar route and their approaches. Submarines are free to transit the route submerged, as that is their normal mode of operation.[27]

The channels of the Ombai-Wetar route are extremely deep.[4] East Timor has refused advances by China seeking off-shore oil rights and permission to set up radar arrays ostensibly to counter illegal fishing.[24] The two straits therefore provide a route for undetected access by nuclear-powered submarines between the two oceans they connect.[4][24]

By the mid-1970s, the Ombai-Wetar route had been identified as one of five international straits essential for passage by U.S. ballistic missile submarines, the others being Gibraltar, Malacca-Singapore, Lombok and Sunda.[24][28] In 1977, a paper published by the International Institute for Strategic Studies, based in London, ranked the Ombai-Wetar route as the second-most-important strait in the world to U.S. defense interests, after the Strait of Gibraltar.[29] The two straits are now also considered by China to be strategically significant.[24]

Children sitting on fishing boats in Suco Maquili, Atauro, in 2010

In East Timor, involvement in fishing is low by comparison with other small island countries. Along the country's portion of the north coast of Timor island, and around Atauro, including within the strait, fishing levels are higher than elsewhere in the country, other than in pockets along parts of its south coast. Many of the fishers fish part time or seasonally, and are otherwise occupied in additional activities such as carpentry, labouring or security work. Most of the fish landings are of small pelagic species, including short-bodied mackerel, sardines (Clupeidae), halfbeaks and scads (Carangidae).[2]

East Timor's whale watching industry is focused on the Ombai-Wetar route, and has been growing rapidly since the 2010s.[16] Annual migrations of whales and dolphins along the route provide some of the best and most accessible whale watching in the world.[16][30]

Dolphins, and even more so the smaller whale species, such as short-finned pilot and melon-headed whales, can be spotted in Wetar Strait all year round. Between October and December, the strait becomes a major migratory route: many species, both large and small, can be observed, including blue, beaked, humpback, sperm, killer, short-finned pilot and melon-headed whales, together with very large dolphin pods.[15]

Cetaceans migrating along the route are often very close to the north shore of East Timor. The coastal mountains around Subaun, on the strait between Dili and Manatuto, include cliffs and hillsides with excellent panoramic views. Networks of local residents record cetacean movements and behaviour, and then report it in 'real time' to researchers and Dili-based whale watching tour operators.[16]