The Torres Strait Particularly Sensitive Sea Area is the northern extension of the Great Barrier Reef PSSA, designated by the International Maritime Organization through Resolution MEPC.133(53), adopted at the 53rd session of the Marine Environment Protection Committee on 22 July 2005. It is not a stand-alone PSSA: the parent area was identified as the world’s first PSSA by Resolution MEPC.44(30) on 16 November 1990, and the 2005 resolution extended that designation to cover the Torres Strait between the tip of Australia’s Cape York Peninsula and the south coast of Papua New Guinea. The single most consequential associated protective measure is a pilotage measure that Australia and Papua New Guinea proposed and that IMO associated with the PSSA through a SOLAS Chapter V navigation circular (SN/Circ.247). Australia gave that measure compulsory effect under its own law from 6 October 2006 for ships of 70 meters or more in length and for loaded oil, chemical and gas tankers of any length. That step set off a continuing legal dispute: the United States and Singapore maintain that an IMO pilotage measure in a strait used for international navigation can only be recommendatory under the transit-passage rules of the United Nations Convention on the Law of the Sea, Part III. The strait is also covered by the mandatory REEFREP ship reporting system operated through REEFVTS and by an IMO two-way route, and the discharge regime overlays the MARPOL Convention annexes that already apply to the Great Barrier Reef. For practitioners planning a transit, the controlling operational constraints are draft, tide and squat, which can be worked through with the under-keel clearance calculator, the squat calculator and the CPA/TCPA tool.
What the Torres Strait PSSA is, and what it is not
A Particularly Sensitive Sea Area is an area that IMO recognizes as needing special protection through IMO action because of its ecological, socio-economic or scientific significance and its vulnerability to damage from international shipping. The operative instrument is IMO Assembly Resolution A.982(24) of 1 December 2005, the Revised Guidelines for the Identification and Designation of PSSAs, later amended by Resolution MEPC.267(68) in 2015. The PSSA framework is described in full in the overview article; the key point for the Torres Strait is that a PSSA designation by itself does not create a no-go zone or a new enforcement power. The protection comes from the associated protective measures (APMs), which must each be a measure IMO already has the competence to adopt: ships’ routeing and ship reporting under SOLAS Chapter V, discharge controls under MARPOL, and pilotage recommendations.
The Torres Strait designation is a textbook example of the distinction. The PSSA status is the umbrella; the teeth are the routeing, the reporting and the pilotage measures adopted under SOLAS and recommended through the IMO circulars. The 2005 resolution did not invent a new legal category for the strait. It recorded that the strait met the PSSA criteria and that the proposing states wished to associate a pilotage measure with it.
There is a second distinction that matters here. A PSSA is not the same as a MARPOL Special Area, though the two overlap in the Torres Strait. The Great Barrier Reef and the Torres Strait are Special Areas under MARPOL Annex IV for sewage and MARPOL Annex V for garbage, which are discharge-control regimes administered solely under MARPOL. The PSSA layer adds the routeing and reporting structure. The two regimes are operationally separate but mutually reinforcing, and a vessel in the strait must satisfy both.
A third distinction is between the IMO PSSA and the various non-IMO conservation designations. The reefs of the strait sit at the northern margin of the Great Barrier Reef World Heritage property inscribed by UNESCO in 1981, and the strait’s wetlands and seagrass meadows are relevant to obligations under the Ramsar Convention on wetlands. Those instruments create reporting and conservation duties on the coastal states. They do not, by themselves, regulate a foreign ship in transit. Only the IMO measures do that, and only to the extent UNCLOS permits.
Geography: a narrow, shallow, reef-strewn international strait
The Torres Strait separates the northern tip of Cape York Peninsula in Queensland, Australia, from the south-western coast of Papua New Guinea. At its narrowest the gap between the two mainlands is roughly 150 kilometers, but the navigable water is far narrower than that figure suggests. The strait is studded with more than a hundred islands and innumerable reefs, sand cays and rock awash, and the practicable deep-draft route threads a single charted channel through them.
The two principal navigation channels are the Prince of Wales Channel in the western strait, the gateway between the Arafura Sea and the Coral Sea, and the Great North East Channel that runs north-east from the Prince of Wales Channel toward the Coral Sea and the open Pacific approaches. The Prince of Wales Channel is the constraining segment for deep-draft traffic: charted least depths along the dredged and surveyed track fall below 12 meters at chart datum in places, against bulk carriers and tankers that routinely load to draughts of 11 to 12 meters or more. A loaded Panamax leaving a Queensland coal terminal for Asia transits the channel with single-figure meter under-keel clearance, and the margin is tide-dependent.
That depth profile is why squat and tide dominate Torres Strait passage planning. A vessel moving at speed in shallow, restricted water sinks bodily and trims by the head or stern, reducing the static under-keel clearance further. The squat effect grows roughly with the square of speed and is amplified in confined channels, so a vessel that is comfortable at 6 knots can lose a meter of clearance at 12 knots. Pilots manage this by metering speed to the available tide and by scheduling the Prince of Wales Channel transit for a tidal window. The arithmetic is the same as that in the squat calculator and the under-keel clearance calculator: static draft, plus squat, plus a safety allowance, against charted depth corrected for height of tide.
Tidal streams add a third constraint. The strait sits between two tidal regimes, and the streams through the Prince of Wales Channel can run hard, setting a deep-draft vessel toward the channel edges where the reefs lie. The combination of a narrow track, shallow water, strong streams and dense reef cover is what made the case for the protective measures, and it is also what makes the strait one of the few places where compulsory pilotage can be argued to be a genuine safety necessity rather than a revenue device.
The vulnerability case: reefs, seagrass, dugong, turtle and people
The ecological case for the Torres Strait rests on a set of habitats and species that are concrete, not abstract. The strait holds some of the largest seagrass meadows in the world, and those meadows support the largest dugong (Dugong dugon) population on Earth, estimated in aerial surveys to run into the tens of thousands of animals. The dugong is a slow-breeding, seagrass-dependent marine mammal classified as vulnerable; a single oil spill smothering a seagrass meadow, or a chronic loss of meadow to turbidity, removes the food base for a population that cannot quickly recover.
The strait is also a globally important area for marine turtles. Green turtles (Chelonia mydas) graze the same seagrass beds the dugong depend on, and the islands and cays host nesting beaches for green and hawksbill turtles. The reefs themselves, at the northern limit of the Great Barrier Reef system, carry the coral, fish and invertebrate diversity that the parent PSSA was designated to protect. A grounding on one of these reefs does the same physical damage seen elsewhere on the Reef: crushed coral, antifoulant contamination and a scar that takes years to recolonize.
The social, cultural and economic criteria carry as much weight here as the ecological ones, which is unusual among PSSAs. The Torres Strait is the home of the Torres Strait Islander peoples, one of Australia’s two recognized Indigenous groups, whose connection to the sea country of the strait is continuous and central to their identity, subsistence and law. Islander communities depend on the dugong and turtle as traditional foods and on the reefs and seagrass for fishing. The strait is not an empty sea lane; it is an inhabited cultural seascape with a living traditional economy. A major spill or a chronic decline in the seagrass would damage that economy directly, and the cultural-heritage criterion of A.982(24) was demonstrated through that dependence.
The scientific and educational criterion was satisfied through the long record of dugong and seagrass research in the strait, much of it carried out by Australian and Papua New Guinean institutions, and through the strait’s value as a reference site for tropical seagrass and dugong ecology. The proposing states documented all three criterion families, ecological, socio-economic and cultural, and scientific and educational, in the submission that became MEPC.133(53).
From MEPC.44(30) to MEPC.133(53): the designation history
The Great Barrier Reef was identified as a PSSA by Resolution MEPC.44(30) on 16 November 1990, the first application of the then-new PSSA concept. The 1990 designation covered the Great Barrier Reef Region from Cape York south to the area below Lady Elliot Island, broadly coterminous with the Great Barrier Reef PSSA and the Great Barrier Reef Marine Park. Australia gave the associated pilotage in the Inner Route and Hydrographers Passage compulsory effect under national legislation from 1991, establishing the model of converting an IMO-recommended pilotage measure into a domestic compulsory regime.
The Torres Strait sits immediately north of the 1990 area, but the original designation did not extend pilotage all the way through the strait to the Great North East Channel. Through the 1990s a series of casualties and near-misses in and around the strait, including bulk-carrier groundings in the approaches, kept the question of extending protection on the agenda. Australia and Papua New Guinea developed a joint proposal to extend the Great Barrier Reef PSSA northward to cover the Torres Strait and to associate a pilotage measure with the extended area.
The joint Australia and Papua New Guinea proposal was considered through MEPC sessions in 2003 and 2004 and adopted at MEPC 53 as Resolution MEPC.133(53) on 22 July 2005. The same MEPC session adopted the Galapagos PSSA as Resolution MEPC.135(53), so the two designations share a session and a date, which is a useful cross-check for the Torres Strait date. The resolution designated the Torres Strait as an extension of the existing Great Barrier Reef PSSA and recorded the proposing states’ intention to introduce a pilotage system.
It is worth being precise about what the resolution did and did not say, because the wording is at the center of the later dispute. The resolution designated the area and noted the proposed pilotage measure. The pilotage measure itself was circulated by IMO as a SOLAS V navigation circular, SN/Circ.247, in recommendatory terms. The resolution did not, and under the PSSA Guidelines could not, by itself make pilotage compulsory for foreign ships in transit. That step was taken by Australia under its own law.
The associated protective measures
The protective package associated with the Torres Strait extension has four operative components, each resting on an existing IMO instrument rather than on the PSSA designation alone.
The first is the pilotage measure, the contested centerpiece, treated in detail in the next section. The second is the two-way route, a designated track through the strait and the Great North East Channel adopted as a SOLAS Chapter V routeing measure, which keeps opposing traffic on managed tracks and steers vessels away from the most sensitive reef and seagrass sub-areas. The two-way route gives the pilot and the vessel a charted, IMO-recognized reference line, published in the IMO Ships’ Routeing publication and on Australian Hydrographic Office charts and electronic chart cells used through ECDIS.
The third is the mandatory ship reporting system, REEFREP, operated through Reef VTS (REEFVTS). REEFREP was recognized by IMO as a mandatory reporting system under SOLAS V/11 by Resolution MSC.52(66) of 30 May 1996, and the Torres Strait extension to the reporting area was adopted by Resolution MSC.171(79) on 9 December 2004 with entry into force on 1 July 2006. Reporting is mandatory under SOLAS V/11, which means every flag state whose ships enter the area is bound to ensure compliance, regardless of where the ship is bound. The REEFVTS center provides traffic, tide and reef-sighting information and maintains a real-time picture of every reporting vessel, working alongside the pilot on board.
The fourth is the MARPOL discharge regime that overlays the PSSA. The strait is a Special Area under Annex IV sewage and Annex V garbage, and the general discharge prohibitions of MARPOL Annex I for oil apply with the rigor expected of a sensitive area, backed by the shipboard oil pollution emergency plan required under Regulation 37 SOPEP. There is no Emission Control Area in the strait; the area is subject to the global sulphur cap under MARPOL Annex VI rather than to a regional ECA.
These four components, the pilotage measure, the two-way route, the mandatory reporting system and the MARPOL overlay, are the working content of the Torres Strait PSSA. The designation packages them; it does not replace them.
The compulsory pilotage measure
Australia gave the IMO-associated pilotage measure compulsory effect under its own law from 6 October 2006, extending the existing Great Barrier Reef Inner Route compulsory pilotage regime northward into the Torres Strait and the Great North East Channel. The compulsory regime, administered by the Australian Maritime Safety Authority under the Navigation Act (then the Navigation Act 1912, later the Navigation Act 2012), applies to vessels of 70 meters or more in length overall and to all loaded oil tankers, chemical tankers and gas carriers irrespective of length. Pilots are licensed and audited by AMSA, supplied through licensed pilotage providers, and allocated by roster, the same machinery used for the Inner Route and Hydrographers Passage.
The pilot boards for the strait transit and conns the vessel through the Prince of Wales Channel, the Great North East Channel and the connecting waters, working to the two-way route and to the tidal window. The pilotage is genuine pilotage, not advisory presence: the pilot’s local knowledge of the channel, the reefs, the tidal streams and the squat behavior of deep-draft ships in the shallow channel is the safety control the measure is designed to deliver. Australian casualty data for the Great Barrier Reef compulsory regime as a whole show a sustained reduction in reef contacts after pilotage became compulsory, and the residual casualties have tended to involve cases where the master overrode the pilot.
The fee structure follows the same model as the Reef Inner Route. The pilotage charge reflects the pilot’s time on board, transport and the administrative levy, and runs into the tens of thousands of Australian dollars for a full Reef-and-strait transit. For a deep-draft bulk carrier or tanker the pilotage cost is small against the value of the cargo and trivial against the cost of a grounding, and the industry has complied at a high rate since 2006 even where the flag state disputes the legal basis.
The practical point that is sometimes missed is that compliance and legality are different questions. Vessels of objecting flag states have, in practice, taken pilots in the Torres Strait, because no master wants to take a deep-draft ship through the Prince of Wales Channel without one and because Australia controls the destination ports. The legal dispute is about whether Australia may compel pilotage as a matter of right, not about whether masters in fact use pilots.
The dispute: transit passage under UNCLOS Part III
The Torres Strait is a strait used for international navigation that connects one part of the high seas or an exclusive economic zone with another, the Arafura and Coral Seas. Under the law of the sea, that classification triggers the transit-passage regime of UNCLOS Part III. Article 37 defines the straits to which the regime applies. Article 38 establishes the right of transit passage, which all ships and aircraft enjoy and which the strait states “shall not hamper” and “shall not suspend.” Article 42 sets out the limited categories of laws and regulations a strait state may adopt for transit passage: safety of navigation and traffic management, pollution prevention by giving effect to international rules on discharge, fishing, and loading or unloading contrary to customs, fiscal, immigration or sanitary laws. Article 44 requires the strait states not to hamper transit passage and to give appropriate publicity to known dangers.
The legal divide turns on whether compulsory pilotage fits inside Article 42. Australia and Papua New Guinea argue that compulsory pilotage is a permissible safety-of-navigation and traffic-management measure, a measure to protect a uniquely sensitive and hazardous strait, adopted with IMO’s blessing through the PSSA designation and the associated circular, and therefore consistent with the coastal states’ Part III competence and with their general environmental duties under UNCLOS Articles 192 and 194. On their reading, requiring a pilot is no different in kind from a traffic-separation scheme, which Article 41 expressly contemplates and which IMO routinely adopts for straits.
The United States and Singapore argue the opposite. Their position is that Article 42 contains a closed list of the laws a strait state may apply to ships in transit passage, that compulsory pilotage is not on that list, and that the right of transit passage in Article 38 cannot be conditioned on taking a pilot. On this reading, IMO may recommend pilotage in a strait, and ships are free to follow the recommendation, but neither IMO nor the coastal state may make it a precondition of passage without converting an unimpeded right into a permission. The objecting states also point to the text of the IMO measure itself: SN/Circ.247 reads in recommendatory terms, which they treat as IMO’s own acknowledgment that the measure could not be made mandatory at the IMO level.
The dispute was aired at IMO before and after the 2005 adoption. The objecting states recorded their concerns in the MEPC and MSC discussions and pressed for clarity on whether the measure was recommendatory, and the issue was considered by the IMO Legal Committee at its 91st session in 2006, which recorded a divergence of views without resolving the underlying legal question. The flag states maintained their objection; Australia maintained its compulsory regime. The matter has never been taken to the International Tribunal for the Law of the Sea or to arbitration, so there is no binding ruling. The practical result is a stable standoff: Australia enforces compulsory pilotage, objecting flag states preserve their legal position on the record, and ships take pilots.
This is the most important precedent question in the whole PSSA system. If a coastal state can make IMO-associated pilotage compulsory in an international strait, the protective reach of a PSSA over transit traffic is large. If it cannot, the PSSA’s strongest measure in a strait is reduced to a recommendation backed only by the coastal state’s control of its ports. The Torres Strait is the case where that question was joined, and it remains open.
The argument has a structure worth tracing because it recurs whenever a strait state proposes a strong measure. The strait states open from the environmental obligations: UNCLOS Article 192 imposes a general duty to protect the marine environment, Article 194 requires states to take measures to prevent pollution, and the PSSA designation supplies the IMO recognition that A.982(24) requires before a coastal state applies a protective measure to foreign ships. The objecting states answer from the lex specialis of Part III: transit passage is a stronger right than innocent passage precisely because it cannot be suspended and cannot be hampered, and Article 42 lists the laws a strait state may apply with a deliberate narrowness that the general environmental articles cannot override. The strait states reply that pilotage is a navigation-safety and traffic-management measure squarely inside Article 42(1)(a) and is no more a hindrance to passage than a traffic-separation scheme. The objecting states close by reading the IMO measure’s own recommendatory wording against the compulsory domestic regime. Neither side has conceded, and because the dispute never reached a tribunal, the strongest reading available to a practitioner is descriptive: the measure is enforced, it is complied with, and its legality is reserved.
REEFREP, REEFVTS and the reporting backbone
REEFREP is the mandatory ship reporting system for the Great Barrier Reef and Torres Strait, operated through the Reef Vessel Traffic Service (REEFVTS) from a center on the Queensland coast. It is a SOLAS V/11 system, which is the feature that gives it international force: a Contracting Government proposes the system to IMO, IMO adopts it, and from then on every flag state must require its ships to comply. The original Reef area was adopted by Resolution MSC.52(66) in 1996, and the Torres Strait extension was added by Resolution MSC.171(79) on 9 December 2004, entering force on 1 July 2006 in step with the pilotage start.
Reporting applies to vessels at or above the system’s length threshold, to vessels carrying hazardous cargo, to towing combinations above a length limit, and to vessels not under command or restricted in their ability to maneuver. The report types are the standard VTS set: a position report on entering the area, a final report on leaving, deviation reports when a vessel departs the two-way route, and periodic position reports for vessels remaining in the area. REEFVTS uses the reports together with AIS data to keep a continuous traffic picture and to pass tide, weather and reef-sighting information to vessels and to the pilot on board.
The legal status of REEFREP is cleaner than that of the pilotage measure, and that is the point. Mandatory ship reporting under SOLAS V/11 is uncontroversial because it does not condition the right of passage; it requires the vessel to report, not to take an action that could be characterized as hampering transit. The objecting flag states accept REEFREP. The reporting system therefore does much of the practical traffic-management work in the strait without raising the Part III question that the pilotage measure raises, which is one reason the reporting layer is the durable backbone of the protective regime.
Under-keel clearance and the operational reality of a strait transit
For the watchkeeper and the pilot, the Torres Strait PSSA reduces to a small number of hard operational constraints, and under-keel clearance is the first of them. The Prince of Wales Channel carries charted least depths below 12 meters at chart datum, and deep-draft bulk carriers and tankers load close to that figure, so the static under-keel clearance is often only a meter or two before any allowance for squat and tide. The transit is therefore planned around the tide: the deepest-draft vessels take the channel on a rising or high tide to add the height of tide to the available depth.
Squat then eats into whatever margin remains. In shallow, restricted water a moving vessel settles bodily and changes trim, and the settlement grows roughly with the square of speed. A deep-draft vessel that holds 12 knots through the Prince of Wales Channel can lose more than a meter of clearance to squat alone, which is why pilots meter speed to the tidal window rather than running for time. The working calculation is the standard under-keel clearance sum, set out in the under-keel clearance calculator: charted depth, plus height of tide, minus static draft, minus squat, minus a safety and weather allowance. The squat component can be estimated with the squat calculator, which applies the Barrass relationship for restricted water.
Traffic management is the second constraint. The two-way route concentrates opposing deep-draft traffic on narrow tracks where passing room is limited, so closest-point-of-approach planning matters: a meeting situation in the Prince of Wales Channel leaves little sea room to open the passing distance, and the timing of a meeting is often arranged through REEFVTS before the vessels are in sight. The geometry of a meeting or crossing is the same problem solved by the CPA/TCPA calculator under the collision-avoidance rules of the COLREG Convention. For the through-route decision, a vessel that elects to avoid the strait entirely faces the long diversion south of Australia, a routeing trade-off of the kind quantified by the great-circle versus rhumb-line distance comparison.
The third constraint is the reef itself. The track is bounded on both sides by reef and shoal, and a vessel that loses steerage, suffers a steering or engine failure, or is set by the tidal stream has little room to recover. This is the reason the strait states pressed for pilotage rather than relying on reporting and routeing alone: the margin for error is small, and the consequence of an error, a grounding on a reef in a dugong and turtle habitat, is severe and slow to heal.
The bilateral frame: the Torres Strait Treaty and Papua New Guinea
The Torres Strait is bounded by two coastal states, and the protective regime is necessarily bilateral. Australia and Papua New Guinea concluded the Torres Strait Treaty on 18 December 1978, in force from 1985, which fixed the maritime boundary between the two countries, established a Protected Zone to safeguard the traditional way of life and livelihood of the Torres Strait Islander and the coastal people of Papua New Guinea, and provided for cooperation on conservation and management. The treaty is the reason the PSSA proposal and the pilotage measure were joint: both states are coastal states to the strait under UNCLOS, and a measure proposed by only one of them would have been incomplete.
Australia legislated the compulsory pilotage that applies in Australian waters and in the Australian-administered area, and Papua New Guinea put parallel arrangements in place under its own pilotage law, recognizing AMSA-licensed pilots as competent for the strait segment and providing for cost recovery across the boundary. AMSA and the Papua New Guinea National Maritime Safety Authority operate the pilotage and the reporting as a continuous service across the maritime boundary, so a vessel does not change pilots or reporting regimes as it crosses from Australian to Papua New Guinean water.
Papua New Guinea later secured a separate PSSA for the eastern approaches. The Jomard Entrance, the passage through the Louisiade Archipelago that funnels traffic toward the Great North East Channel and the strait, was designated a PSSA by Resolution MEPC.283(70) in 2016 at Papua New Guinea’s request, with recommended two-way routes and a ship reporting system. The Jomard designation is a separate PSSA, not part of the Torres Strait extension, but it complements it by extending protective routeing and reporting to the eastern feeder route. Together the Torres Strait extension and the Jomard Entrance cover the principal deep-draft path between the Coral Sea and the strait.
Relationship to the Great Barrier Reef PSSA and Marine Park
The Torres Strait extension is legally and administratively part of the Great Barrier Reef PSSA, and the two are best read together. The parent designation under MEPC.44(30) gave compulsory pilotage to the Inner Route between Cairns and Cape York and to Hydrographers Passage from 1991; the Torres Strait extension under MEPC.133(53) carried that regime north through the strait from 2006. The two-way route, the REEFREP reporting and the MARPOL Special Area overlays run continuously from the southern Reef through the strait, so a vessel transiting from a southern Queensland coal or alumina terminal to Asia stays inside one protective regime for the whole passage.
The administrative overlap is with the Great Barrier Reef Marine Park, the Commonwealth marine protected area declared under the Great Barrier Reef Marine Park Act 1975 and managed by the Great Barrier Reef Marine Park Authority. The Marine Park and the PSSA are not identical in boundary: the Marine Park is a domestic conservation and zoning instrument, and the PSSA is an IMO designation, but they cover broadly the same waters and reinforce each other. The northern boundary of the Marine Park lies in the southern Torres Strait region, and the dugong and seagrass values that the PSSA protects in the strait are continuous with the values the Marine Park protects to the south. The conservation case for the Torres Strait was, in part, that it is the same ecosystem as the Reef and should not be left less protected merely because it is a busier and more constrained shipping route.
The casualty record reinforced the continuity argument. Groundings in and near the strait through the 1990s and 2000s, including bulk carriers that ran onto reefs in the approaches, were of the same character as the major Reef groundings to the south and made the case that the strait needed the same compulsory pilotage that the Inner Route already had. The 2005 extension closed that gap.
The continuity also runs through the trade pattern. The deep-draft traffic in the strait is dominated by bulk carriers and tankers loading at Queensland and other east-coast Australian terminals (coal, alumina, sugar and petroleum products) and proceeding to Asia and the Indian Ocean, the same trades that feed the Reef Inner Route to the south. For those vessels the strait is the short way out: the alternative is to round the south of Australia, a diversion of roughly 1,500 nautical miles and several days’ steaming that is economically unattractive except where a vessel is denied entry to the strait on safety grounds. The economics therefore funnel almost all of the deep-draft Asia-bound trade through the one constrained channel, which is why a protective regime built around pilotage, routeing and reporting, rather than around an area-to-be-avoided that simply excludes traffic, was the only practicable design for the strait.
Enforcement, limitations and practitioner notes
The Torres Strait PSSA shows clearly where the legal teeth of a PSSA stop. The designation does not create a no-go area, and it does not give the coastal state any enforcement power it would not otherwise have under UNCLOS. The reporting requirement is enforceable because SOLAS V/11 binds every flag state and because Australia can act through port-state control at the next Australian port of call. The two-way route is enforceable as a SOLAS V/10 routeing measure on the same basis. The MARPOL discharge controls are enforceable as MARPOL controls. The pilotage requirement is the one measure whose enforceability against a foreign ship in transit is genuinely contested, and that contest is unresolved.
Several practitioner-grade caveats follow. First, the pilotage thresholds are precise and easy to misapply: the trigger is 70 meters length overall, or any length for a loaded oil, chemical or gas tanker. A vessel under 70 meters carrying a non-tanker cargo is not caught by the compulsory regime, though it remains subject to reporting and routeing. Second, the legal status of the pilotage is jurisdiction-dependent: a master should treat it as compulsory because Australia controls the destination port and will enforce, but the flag state’s formal legal position may differ, which matters in liability and insurance contexts. Third, the PSSA does not relax the right of transit passage; a coastal state is obliged under Article 44 not to hamper transit and not to suspend it, so the protective measures must be applied in a way consistent with that duty.
There are operational pitfalls as well. The under-keel clearance margin is small and tide-dependent, so a passage plan that does not pin the Prince of Wales Channel transit to a tidal window can leave a deep-draft vessel without adequate clearance once squat is included; this is a documented cause of touch-and-go contacts. Departing from the two-way route in a non-emergency is a reporting and routeing breach. Failing to make the REEFREP reports is a SOLAS V/11 breach detectable through AIS and actionable at the next port. And the discharge regime under MARPOL Annex IV and Annex V is stricter than the global default, so a garbage or sewage discharge that would be lawful on the open sea is a Special Area offence inside the strait.
The limit that matters most for the wider system is the precedent limit. The Torres Strait is the test case for compulsory pilotage in an international strait, and because it was never litigated, it neither confirms nor forecloses the practice for other straits. A coastal state proposing compulsory pilotage elsewhere cannot point to a binding ruling in its favor, and an objecting flag state cannot point to one against. The Torres Strait stands as a worked example of how far a PSSA can reach over transit traffic and of exactly where the legal argument runs out.
See also
- Particularly Sensitive Sea Areas: overview
- Great Barrier Reef PSSA
- Galapagos PSSA
- Wadden Sea PSSA
- Tubbataha Reefs PSSA
- SOLAS Convention
- COLREG Convention
- MARPOL Annex IV sewage
- MARPOL Annex V garbage
- Under-Keel Clearance (UKC) calculator
- Squat (Barrass) calculator
- CPA / TCPA calculator
- Great Circle vs Rhumb distance comparison
References
- International Maritime Organization, Resolution MEPC.133(53), Designation of the Torres Strait as an Extension of the Great Barrier Reef Particularly Sensitive Sea Area, adopted 22 July 2005.
- International Maritime Organization, Resolution MEPC.44(30), Identification of the Great Barrier Reef as a Particularly Sensitive Area, adopted 16 November 1990.
- International Maritime Organization, Resolution A.982(24), Revised Guidelines for the Identification and Designation of Particularly Sensitive Sea Areas, adopted 1 December 2005, as amended by MEPC.267(68).
- United Nations Convention on the Law of the Sea, 1982, Part III (Articles 37 to 44), straits used for international navigation and the transit-passage regime.
- International Maritime Organization, SN/Circ.247, associated protective measure recommending pilotage in the Torres Strait, 2005.
- International Maritime Organization, Resolution MSC.171(79), amendments to existing mandatory ship reporting systems (Torres Strait extension to REEFREP), adopted 9 December 2004.
- Australian Maritime Safety Authority, Coastal Pilotage and REEFVTS guidance.
- Torres Strait Treaty between Australia and Papua New Guinea, 18 December 1978.