State Practice on the
Establishment of Multiple
Maritime Boundaries:
Assessing the Challenges of
Separating Seabed and Water Column
Boundaries
Professor Clive Schofield
The Australian National Centre for Ocean
Resources and Security (ANCORS)
Challenge Lead, Sustaining Coastal and
Marine zones
UOW Global Challenges
University of Wollongong
Australia
Continental Shelf
Territorial Sea Baseline
Internal waters
Baselines and Maritime Zones
The
Area
Sea-bed, Subsoil, Sedentary Species
(Extended
Continental Shelf)
Exclusive
Economic Zone (EEZ)
High Sea
Water Column,
Sea-bed, Subsoil
12 M
Territorial
sea
Shelf
Contiguous
zone
200 M
12 M
Sea Level
Upper
Slope
Animation by Arsana & Schofield, 2012
Source: TALOS Manual (5th edition, 2014)
Plateu
or
Terrace
Lower
Slope
Rise
Deep
Ocean
Global Maritime Jurisdiction
Source: Global Maritime Boundaries Database
Source: CIA
Implications of Extended Maritime Claims
• Extended maritime claims
 200 nautical mile claims = 147km2 million (43nm2 million)
 41% of the area of the oceans
 19% of Earth’s surface
•
Proliferation in the number of “new” potential
maritime boundaries
 Less than 50% delimited
 A young process
 Many agreements only partial
 Continental shelf delimitations prior to the introduction of
the EEZ
• Trend towards ‘upgrading’ continental shelf
boundaries to ‘single maritime boundaries’
Ireland-UK
• Continental shelf
delimitation (1988)
• ‘staircase’ effect
• Problematic to
‘upgrade’ to a single
maritime boundary?
Source: International Maritime Boundaries
Ireland-UK
• UK-France, UK-Ireland
“grey zone”
arrangements
• Operational
understandings
enforcement
• Longstanding navy-tonavy cooperation in place
• Common fisheries
context
Source: UKHO
Fishery Grey Zones
Ireland
UK
France
Source: UKHO
Ireland-UK (2013)
• Conversion of
continental shelf
boundary to EEZ
delimitation
• Minor adjustments
along the line
• Exchange of equivalent
areas and equivalent
potential for
exploitation
Continental Shelf/EEZ Delimitation
LOSC Articles 74 and 83
1. The delimitation of the continental shelf
(exclusive economic zone) between States
with opposite or adjacent coasts shall be
effected by agreement on the basis of
international law, as referred to in Article 38
of the Statute of the International Court of
Justice, in order to achieve an equitable
solution.
The equitable principles/relevant circumstances rule
Minimal Guidance?
The delimitation provisions in the
Convention have been termed: “a last
minute endeavour…to get agreement on
a very controversial matter” and
therefore “consciously designed to
decide as little as possible”
(Eritrea/Yemen Arbitral Tribunal, 1999)
EEZs and the Decline of Geophysical Factors
• LOSC led to a significant
shift away natural
prolongation arguments
• Introduction of the EEZ:
seabed rights to 200nm
• Libya-Malta case (1985):
“the geological and
geomorphological
characteristics of those
areas...are completely
immaterial” (Libya/Malta
Case, para.39).
• Some claims persist (e.g.
Australia, China, Korea)
Source: Limits in the Sea
Methodology
• Any method of boundary delimitation is
acceptable with the support of the parties,
even if inconsistent with other approaches –
as long as the interests of third parties are
not infringed
• Clear that one method has been used far
more than any other: equidistance
• Emergence of a three-stage approach

Provisional line constructed on the basis of equidistance
Timor Sea
Delimitations
• Impact of Timor
Trough on location
of AustraliaIndonesia
continental shelf
boundary of 1972
• 1981 Provisional
fisheries
arrangement
• 1997 Perth Treaty
(EEZ)
Timor Sea Boundary Arrangements
Source:
Geoscience
Australia
Maritime Delimitation in the Torres Strait
Source:
Geoscience
Australia
Source:
Geoscience
Australia
Practical Challenges of Separate Boundaries
• Non-coincident continental shelf and water
column boundaries raise problematic issues
concerning the management of:




Tensions between resource rights
Installations and structures
Marine environmental protection
Marine scientific research
• Example:
 If Australia is to access and develop resources in its
continental shelf overlain by Indonesian EEZ it will
necessarily impair Indonesia’s rights
Problematic Fisheries Enforcement Issues
• In April 2008 the Australian Fisheries
Management Authority (AFMA) apprehended
33 Indonesian fishing vessels suspected of
illegal fishing “off northern Australia”
• 9 of the vessels (& 55 crew) involved had NOT
been illegally fishing (N. of provisional fisheries
enforcement/EEZ line and not fishing for
sedentary species)
• Compensation paid and crews returned to
Indonesia
Multiple Maritime Boundaries
• Certainly possible but practice limited
• Potentially problematic to implement
• Strong trend towards ‘single maritime boundaries’
 Not always possible
• Multiple boundaries are better than none!
• Potential for increasing practice
• Challenges associated with separate seabed and
water column boundaries can be overcome:
 context of a complex, multi-zonal system
 increasing intensity and diversity of marine activities
 enhanced use of tools such as marine spatial planning