Torres Strait PSSA | MAPS | IMO Documents | "Strait Facts"/Risk Assessment | Watch Video | Marine Notices
Protective Measures | Close Calls | Shipping Incidents | More Background Reading
"Strait Facts"/Risk Assessment
- Torres Strait lies between Papua New Guinea and the northern tip of the Australian continent. Many of the islands in the strait are inhabited by the Torres Strait people. It is a vital economic link being the only shipping route between the Arafura and Coral Seas. Vessels bound from many major Asian ports for eastern Australia, PNG, and New Zealand pass through the strait. Numerous reefs and shoals make the strait un-navigable except for one narrow route
- There are approximately 3000 transits of Torres Strait per year by vessels of LOA greater than 50 metres. Traffic comprises bulk carriers 38%, general cargo 28%, containers 15%, loaded tankers 12%.
- Much of the navigable route through Torres Strait is confined in both width and depth. Entry to western Torres Strait is via Varzin Channel with a minimum width of 0.3 nm, and depth of 10.5 metres. Passage through central Torres Strait is via Prince of Wales Channel with minimum width of 0.3 nm and depth of 11.0 metres.
- The recommended maximum draft for transiting ships is 12.2 metres with an under-keel clearance of 10% of draught. Deeper draught vessels (greater than about 9 metres) must make use of tidal windows and reduce speed to reduce squat. Accurate calculation and careful use of the available tidal height is essential for a safe transit of the strait. For this reason all vessels over 70 metres in length carry a pilot licensed by AMSA.
- The narrow channels connect two entirely different oceanic tidal regimes. The tidal regime is extremely complex and tidal heights frequently deviate significantly from those predicted. Very strong tidal streams occur throughout Torres Strait and rates of up to 8 knots may be experienced. The region is subject to tropical squalls and heavy rain with much reduced visibility.
- To cater for the navigational difficulty of the strait AMSA maintains 31 major and minor navaids (lights and buoys), five transmitting tidal height gauges, one transmitting tidal stream meter, a Vessel Traffic System and radar coverage. An Emergency Towing Vessel is on call.
- It is not unusual for two or three deep-draught vessels to be manoeuvring in the same confined stretch of water as they make use of the available tidal height. A major collision or grounding incident in these confined waters has the potential to close the strait which would then force deep draught vessels to take long diversionary routes. The economic consequences of this have been assessed as significant.
Torres Strait Environment
The tidal influences of two ocean systems result in frequent anomalous tidal regimes and have a great effect on the area’s biodiversity. The massive freshwater and sediment input from nearby coastal rivers further influence this unique marine ecosystem. Benthic communities, fish assemblages, seagrass coverage and coral communities have all been well documented.
The Torres Strait provides critical habitat for many vulnerable and endangered species, including dugongs and turtles. A recent United Nations Environment Programme report recognises the Torres Strait as 'the most important dugong habitat in the world.' The extensive seagrass beds support six species of turtle. Torres Strait supports one of the world’s few remaining major hawksbill turtle breeding grounds with rookeries in western, central and eastern Torres Strait.
The Torres Strait supports commercial fisheries for prawns, mackerel, and tropical rock lobster to name but a few. Several thousand people live in small coastal communities on Cape York, on the islands off the southern coast of Papua New Guinea and on the larger islands of the Torres Strait itself. The Torres Strait Islander community is ethnically, culturally and linguistically unique. These Indigenous people rely on the marine resources of the Torres Strait for their livelihoods and for food.
The Torres Strait contains a variety of biogeographical qualities ranging from mangrove islands of terrigenous origin in the north, through to the sand cays in the central region, to the highly fertile volcanic islands in the east, to the granitic terrestrial islands in the west.