1 Vessel traffic characteristics
Operational factors
1.1 The vicinity of TRNP is regularly visited by passenger
boats carrying scuba divers into the Park and fishing vessels
conducting fishing operations outside the Core Zone. Passenger boats
voyaging into the TRNP are strictly regulated by the Tubbataha
Management Office and must call on the ranger station before
proceeding to the designated dive sites (TMO 2008). Such boats are
usually smaller kinds of boats and yachts. On the other hand,
fishing vessels are often wooden vessels domestically registered,
operating from other parts of the country. Management of the TRNP
for the most part has effectively kept domestic fishing activity out
of the Core Zone, which is designated as a "no-take" area. Fishing
operations take place mainly in the Buffer Zone (TPAMB 2014). Both
commercial fishers and small-scale Filipino fishers use fish
aggregating devices called payao to attract valuable pelagic fish
(TPAMB 2014). These types of fish aggregating devices normally
involve buoys or floats with clusters of material, floating just
beneath the sea surface, and anchored to the seabed with rope or
chain. They may pose navigational hazards due to the possibility of
entanglement with propellers of passing ships if they are run over.
In addition, foreign poachers engaged in illegal fishing have often
been found, and boats of local fishers collecting valuable topshells
have been seen entering the Park at night (TPAMB 2014). Given the
illegality of their activity, poachers surreptitiously entering,
operating in, or exiting the Park area may pose collision hazards.
1.2 There has been only one instance to date where the
Philippine Government issued a petroleum exploration contract with
an area that included parts of the TRNP. This contract has not been
implemented as of the time of this application, and the TPAMB has
requested the Department of Energy to exclude the area of the TRNP
from the said contract (TPAMB 2014).
Vessel types
1.3 Satellite AIS-based data, procured via NORAD and analysed
and processed by the Australian Maritime Safety Authority, for the
12-month period from October 2012 to September 2013 show numerous
and varied ships passing the TRNP at varied distances. Cargo ships
constitute the absolute majority (approx. 70%) of such vessels,
followed by tankers (approx. 10%) and other types of ships (approx.
18%). These do not include ships not equipped by AIS, particularly
numerous smaller domestic vessels. Available data indicate that at
minimum, total vessel traffic passing in proximity of the TRNP Core
Zone may be categorized in table 1.
|
Distance from TRNP Core Zone
|
Type
|
20 NM
|
30 NM
|
40 NM
|
50 NM
|
Cargo
|
2,225
|
2,645
|
2,922
|
3,152
|
Fishing
|
1
|
1
|
1
|
1
|
Passenger
|
6
|
6
|
10
|
11
|
Tanker
|
288
|
349
|
397
|
442
|
Other
|
591
|
709
|
778
|
845
|
TOTAL
|
3,111
|
3,710
|
4,108
|
4,451
|
Table 1: Total number and types of ships that passed within certain
distances from the TRNP Core Zone between October 2012 and
September 2013
Traffic characteristics
1.4 TRNP lies at the intersection of north-south and
east-west shipping routes that traverse the Sulu Sea, connecting the
South China Sea to the Celebes Sea and to the Pacific Ocean
respectively. At least 4,451 AIS-equipped vessels passed within 50
NM around the TRNP, the majority (some 75%) along the north-south
route that connects Northeast Asia with Oceania. Traffic passing
along the North-South route is described below likewise in terms of
distance from the TRNP Core Zone, set out in table 2, below.
|
Distance from TRNP Core Zone
|
Type
|
20 NM
|
30 NM
|
40 NM
|
50 NM
|
Cargo
|
2,100
|
2,470
|
2,715
|
2,882
|
Fishing
|
1
|
1
|
1
|
1
|
Passenger
|
4
|
4
|
7
|
8
|
Tanker
|
198
|
237
|
270
|
291
|
Other
|
524
|
625
|
689
|
735
|
TOTAL
|
2,827
|
3,337
|
3,682
|
3,917
|
Table 2: Number and types of ships that passed within certain
distances from the TRNP Core Zone, along the North-South
routes, between October 2012 and September 2013
1.5 North of the Sulu Sea, ships passing along the North-South route pass
into/out of the area through the Mindoro and Tablas Passages astride
the Philippine island Province of Mindoro, converging/diverging east
of the TRNP (refer to figure 1, below). A significant proportion
pass within 10 NM of the Core Zone, i.e. through the TRNP Buffer
Zone. This is consistent with actual observations using partial
radar coverage from the TRNP ranger station, which has recorded
multiple transits of vessels within the Buffer Zone between
2010-2013. These ships then pass out/into the area via the Sibutu
Passage.
1.6 International maritime traffic through the Sulu Sea on this route
likely connect major ports in the Philippine island of Luzon (e.g.
Manila, Batangas) and Northeast Asia with ports in Indonesia, Papua
New Guinea and Australia.
1.7 Traffic passing along the East-West route is distributed as follows,
likewise in terms of distance from the TRNP Core Zone – refer to
table 3, below.

Figure 1: Traffic density plot of ships travelling along
North-South routes near the TRNP
|
Distance from TRNP Core Zone
|
Type
|
20 NM
|
30 NM
|
40 NM
|
50 NM
|
Cargo
|
178
|
265
|
350
|
490
|
Fishing
|
0
|
0
|
0
|
0
|
Passenger
|
4
|
4
|
7
|
7
|
Tanker
|
105
|
138
|
167
|
208
|
Other
|
97
|
130
|
150
|
192
|
TOTAL
|
384
|
537
|
674
|
897
|
Table 3: Number and types of ships passing within certain distances
from the TRNP Core Zone, along the East-West routes, between
October 2012 and September 2013
1.8 Ships passing along the East-West route enter/exit the Sulu Sea
through the Balabac Strait; those that traverse through the Bohol
Sea are brought in proximity of the southern portion of the TRNP
(see figure 2). Compared with ships on the North-South route, less
numbers of vessels cross into the Buffer Zone around the TRNP.
1.9 International maritime traffic through the Sulu Sea on this East-West
route likely call on major Philippine ports of Cebu and Iloilo from
other ports in the Far East. The proportion of vessels that continue
on through the archipelago and out by the Surigao Strait from this
area is significantly less.

Figure 2: Traffic density plot of ships travelling along
the East-West route near the TRNP
Harmful substances carried
1.10 The significant proportion of chemical and oil tankers
passing within 10 NM of the TRNP Core Zone is a cause for concern. A
closer examination of the AIS data show that shipping routes running
through the east and west of the Park bring vessels in closest
proximity to the TRNP Core Zone. Data indicates that the major route
is to the east, with more than 774 vessels passing along a
north-south route within 7.5 NM of the Park. This included 89
chemical tankers (11.49%) and 185 oil tankers (23.9%). Several
thousand vessels pass annually along this north-south route further
offshore. To the west of the Park, some 165 vessels including 31
chemical tankers (18.7%) and 46 oil tankers (27.9%) travelled within
9 NM of the Park along another north-south route.
1.11 The threat of oil and chemical pollution and potential
catastrophic impact on coral reefs is well known. With oil and
chemical tankers passing so close to the TRNP, there is a
significant risk of accidental spills and even grounding on the
reefs. Notably, the two successive ship-grounding incidents that
took place in 2013 (the USS Guardian in January and the
Min Ying Pu in March) were both travelling along
north-south routes.
2 Natural factors
Hydrographical
2.1 The TRNP is located in a region of the Sulu Sea of varied depth
ranging from 1,490 to 2,769 m. Charts indicate that the Tubbataha
Reefs rise above these deep waters abruptly, forming separate
underwater pinnacles topped off by coral reef structures. Depths can
change radically, from 1,000 m to less than one metre within a
distance of only one nautical mile around the reefs. This steeply
rising slope contributes significantly to the risk of grounding for
vessels in the area. The reefs provide little protection from strong
winds and surface currents.
2.2 Hydrographic information from the Philippine Coast Pilot Guide
(NAMRIA 1995) describes all reefs within the TRNP in very clear
terms as inherent dangers to navigation:
-
"The North and South Atoll of Tubbataha Reefs are
considered to be dangerous reefs separated by a deep
channel about 5 miles wide.
-
The North Atoll is oblong in shape and encloses a lagoon
2 miles wide and 5 miles long, with depths of 7.3 to
32.9 m at mud bottom. There are no passages through
the barrier reef into the lagoon; only small
launches can cross the barrier reef at high tide.
Deep water is close to the outer edge of the reefs,
and no anchorages are available. North Islet,
Central Islet, and a number of small black rocks are
the only objects that appear above high water. At
low water, a large number of detached sand cays or
ridges, each about 91 m long and 9 to 18 m, can be
seen along the entire length of the reef. North
Islet is covered with gravel and some guano.
-
The South Atoll is about 4.5 miles long North and South
with several black rocks and sand cays visible at
high water.
-
South Islet is made up of loose, white sand about 1.5 m
above high water, and is protected by riprap. The
39.6 m cylindrical, steel-framed tower which used to
be a lighthouse on this islet is very prominent.
-
Jessie Beazley Reef, about 18 miles north of Tubbataha
Reef Light, extends about 640 m in a north-westerly
direction and is about 137 m wide. At the centre of
the reef is a small hill of broken coral about 1.8 m
high, devoid of vegetation. At low water, the reef
bares over a considerable area. Birds can sometimes
land on the bare parts of this reef. White sand cay
is readily visible by day at a distance of 3 to 5
miles."
Meteorological
2.3 The Sulu Sea within which the TRNP is situated is a deep sea in the
Southeast Asian region located along the south western quadrant of
the Philippines. It is bounded by Palawan Island on the west,
Mindoro Island to the north, Panay Island and Mindanao Island to the
east, the Sulu Archipelago to the southeast, and Borneo to the
southwest. Weather and climate is strongly influenced by the East
Asian Monsoons and the seasonal migrations of the Inter-tropical
Convergence Zone (ITCZ) and the El Nino Southern Oscillation (ENSO).
A north-easterly wind prevails in winter and a south-westerly wind
prevails in summer, but otherwise it is very variable during the
transitional periods (Oppo et al. 2003; Latiff et al. 2014). Sudden
heavy rainfalls are known to occur appear within the Sulu Sea
region, posing hazards to shipping (Butt and Johnson, 2013).
2.4 Rough seas are present from July to October and November to March.
Rainfall is highest in the Sulu Sea from May through November. From
June through September, the ITCZ rainfall merges with the East Asian
Monsoon. By October and November, the East Asian summer monsoon
rains are over, and the dry season starts in the northern SCS but
reaches its seasonal maximum in the southern SCS due to the
southward position of the ITCZ (Oppo et al. 2003). The Philippines,
including the Sulu Sea, is also located within the tropical "typhoon
belt" regularly traversed by typhoons. On average, about 20 tropical
cyclones develop within the Philippine Area of Responsibility each
year, of which around half make landfall (PAGASA 2009). These
disturbances periodically aggravate weather and sea conditions in
the Sulu Sea, thus sudden violent storms, heavy rainfall, and strong
winds increase the risk of navigational incidents.
Oceanographic
2.5 The Sulu Sea is a semi-enclosed basin connected to surrounding seas
over shallow sills. It is surrounded by major landmasses such as
Palawan, Borneo, Mindanao, Panay, Antique, and Mindoro, as well as
connecting several bodies of Philippine waters such as the Linapacan
and Balabac Straits, the Sibuti Passage, Moro Gulf, Dipolog Strait,
Bohol Sea, Panay Gulf, and Mindoro Passage. The Mindoro Passage to
the north/northwest is the deepest passage at 420 m, connecting the
Sulu Sea to the South China Sea, and with the Java Sea across the
shallow Sunda Shelf. The Sibutu Passage to the south is the next
deepest passage, connecting the Sulu Sea to the Sulawesi Sea (Oppo
et al. 2003). The TRNP lies between these two passages, which also
form the entry/exit points for North-South routes traversing the
Sulu Sea. Water circulation patterns in the Sulu Sea show that there
is an inflow from the South China Sea at the Mindoro and Balabac
Straits, and an outflow into the Sulawesi Sea at the Sibutu Passage.
There is a cyclonic circulation in the southern basin (Han et al.
2009). A strong current forms in the northeast Sulu Sea where
currents from the Mindoro and Tablas straits converge. These
converging currents are also entry/exit points for North-South
shipping routes. Surface current speeds have been measured to be as
much as 100 cm/sec (Han et al. 2009).
2.6 Strong westward currents in the Bohol Sea carry the surface water of
the western Pacific from the Surigao Strait into the Sulu Sea via
the Dipolog straits. In the Sibuyan Sea, currents flow west which
carry the surface water from the Western Pacific near the San
Bernardino Strait into the Sulu Sea via the Tablas Strait (Han et
al., 2009). Surface currents exhibit strong variations or reversals
from winter to summer, with the TRNP forming a centre around which
the currents circulate. Generally, during the South West Monsoon,
waters flow in a clockwise motion around the TRNP, driven by
currents from the Dipolog and Linapacan Straits (Han et al., 2009).
The fact that TRNP is located at the centre of this circulation
pattern increases the possibility that any discharges or vessels
adrift near TRNP will likewise be carried around and into its
boundaries.
3 Other Information
3.1 Since 2010, TRNP Park Rangers have been collecting and compiling
information on impacts of international shipping traffic around the
TRNP, albeit with limited capabilities due to the isolation and
inherent limitations of surveillance capabilities of the Park Ranger
Station. Annual records have been based on personal observations of
Park Rangers and extremely limited radar coverage of the immediate
vicinity of the TRNP. A review of the records of limited radar
coverage during the period from 2010-2013 echoes the upward trend of
ship transit, notably passing through the TRNP Buffer Zone. Refer
table 4, below.
Year
|
No. of Ships
Tracked
|
Monthly
Average
|
Rate of
Increase
|
2010
|
3,358
|
280
|
-
|
2011
|
4,253
|
363
|
23%
|
2012
|
3,616
|
302
|
-20%
|
2013
|
5,546
|
462
|
35%
|
Table 4: Number of ships tracked by the TRNP Park Ranger Station with
extremely limited radar coverage
3.2 The upward trend in ship transits around the TRNP translates into an
expected increasing risk in shipping-related impacts, both
operational and accidental. Ship groundings have been demonstrated
as the most prominent risk, followed by pollution from discharges. A
recent study of maritime trade and traffic trends in the
Sulu-Sulawesi Region concluded that all global trade forecasts
indicate "higher volumes of international shipping will transit
through or close to Philippine national waters and as a consequence
increase the vulnerability of the Tubbataha Reefs Natural Park". It
pointed out that the potential increase in very large vessels
transiting through the area to service the ore, coal and LNG trades,
and growing populations around the Sulu-Sulawesi Region that would
likely also increase import activities and the corresponding number
of vessels operating in the area, also posed significant threats.
(Butt and Johnson 2013).
3.3 A separate study that mathematically modelled ship incident risks
around TRNP corroborated the above report by concluding that
"incident probabilities and monetary value at risk (MVR) have
increased in recent years; the probability of pollution in 1999-2007
increased by about 60% for South-East Asia compared to 1979-1998,
and the associated MVR for tankers has doubled." It further noted
that the increase of pollution risk close to the TRNP is even larger
(Heij et al. 2013).
3.4 Park rangers have documented a notable increase in the amount of
foreign, non-Philippine marine debris (product packaging, plastic
containers) collected at the TRNP ranger station, indicating a clear
correlation between the amount of shipping traffic and the amount of
marine debris washed ashore at the park ranger station (refer to
table 5, below).
Year
|
Kg of debris collected
|
2010
|
198
|
2011
|
627
|
2012
|
635
|
2013
|
1,460
|
Table 5: Weight of marine debris collected annually by TRNP Park
Rangers
3.5 Ship groundings have occurred on Tubbataha Reefs. Available records
indicate that as early as 1925, the British steamship Egremont
Castle ran aground near the lighthouse on South Atoll,
and in June 1949, the US steamer Flying Cloud ran aground
near the South Island. Despite modern navigational technologies and
accurate charting, such groundings have continued to take place. In
January 2013, the US Navy minesweeper USS Guardian ran
aground on the South Atoll and had to be completely dismantled for
removal. Shortly after, in March 2013 the Chinese fishing vessel
Min Ying Pu ran aground on the North Atoll and had to
be salvaged (TPAMB 2014). These successive incidents in the TRNP
have demonstrated its continued exposure to high risks posed by
international shipping activity. The increase in shipping activity
around the TRNP denotes a corresponding increase in risks of similar
ship groundings.
3.6 Chemical and oil spill simulations conducted for the Tubbataha
Management Office by the Physical Oceanography Laboratory of the
Marine Science Institute show that at any given month, due to the
proximity of several shipping routes around the TRNP, there is a
very high probability that pollutants from chemical or oil spills
will cross into the boundaries of the TRNP. Depending on the
distance, time of year, monsoon and sea conditions, in the worst
case scenario (outside of a vessel grounding) pollutants can take as
little as four hours for chemical spills and five hours for oil
spills. In the best case scenario, a chemical/oil spill threat can
take as much as 8½ days before reaching the TRNP. Again, the
increasing trend in shipping activities around the TRNP will result
in a corresponding increase in risks of accidental chemical and oil
spills (Villanoy et al. 2015).
3.7 In case of a marine incident at or in the vicinity of the TRNP, there
are only two government vessels available in the nearest Coast Guard
District operating base at Puerto Princesa City, a 35 m Search and
Rescue Vessel and a 30 m Fisheries Monitoring, Control, and
Surveillance patrol vessel. It will take such vessels approximately
10 hours to respond to an incident at the TRNP, assuming that the
said vessels are not being used elsewhere and are capable of taking
the stricken vessel in tow. Private salvage companies based in
Manila with dedicated salvage capability will take at least 24 hours
to respond to a marine casualty or incident in the vicinity of the
TRNP. Moving the concentration of shipping away from the Park
significantly reduces the risks of incidents and may provide just
enough additional time for Park Rangers and other government
agencies to prepare adequate incident response measures.