OA and Sustainable Ocean Planning

1. Outcome

Practitioners will gain practical understanding of four decision use cases: sustainable ocean economy roadmaps that integrate economic development targets with ecosystem health thresholds; SDG 14 implementation planning that uses accounting-derived indicators to track progress on marine pollution, ecosystem management, fisheries sustainability, and economic benefits; integrated coastal management that connects land-based pressures to marine outcomes through physical supply and use tables; and Marine Spatial Planning that organises the spatial allocation of ocean activities using coherent, integrated data supporting analysis of trade-offs and synergies.

2. Requirements

• TG-0.1 General Introduction to Ocean Accounts—provides foundational understanding of Ocean Accounts, the Ocean Accounts Framework, and the conceptual basis for measuring sustainability through changes in natural capital

3. Guidance Material

3.1 What is sustainable ocean planning?

Sustainable ocean planning encompasses the processes through which governments, communities, and other stakeholders make decisions about how ocean and coastal areas will be used and managed. These decisions concern the spatial allocation of activities, the regulation of resource extraction, the conservation of ecosystems, and the pursuit of economic objectives in ways that maintain or enhance the long-term productivity and resilience of marine environments. As established in TG-0.1, sustainable ocean development entails three interconnected objectives: advancing ocean-based economic activities that provide sustainable livelihoods, ensuring equitable distribution of benefits across society, and conserving and enhancing marine ecosystems and their ecological processes^[1].

The practical challenge for sustainable ocean planning lies in reconciling competing demands on ocean space and resources. Fishing communities, shipping industries, offshore energy developers, tourism operators, conservation interests, and coastal residents all have legitimate claims on how marine areas should be managed. Planners require integrated information systems that can reveal the relationships between these different uses and the environmental conditions that underpin them. Traditional approaches to ocean management, which often address individual sectors or issues in isolation, have proven inadequate to the complexity of managing socio-ecological systems where environmental health underpins economic productivity^[2].

Decision use cases for sustainable ocean planning

Ocean accounts support four principal decision use cases in sustainable ocean planning (see Section 3.5 for planning framework descriptions and Table 3.2.2 for required accounts).

Sustainable ocean economy roadmaps integrate economic development targets with ecosystem health thresholds. Asset accounts for fish stocks, mangroves, coral reefs, and seagrass meadows provide baseline values against which depletion or enhancement can be measured (TG-3.1 Asset Accounts). Ocean economy thematic accounts quantify current contributions to GDP and employment (TG-2.5 Structure and Function of the Ocean Economy). Combined presentations of natural and produced capital stocks enable planners to assess whether blue economy growth is generating real wealth or merely converting natural capital into economic output (TG-3.8 Combined Presentations). The 2025 SNA treatment of depletion as a production cost provides a direct mechanism for this assessment: when extraction exceeds sustainable yield, net domestic product falls, signaling unsustainable resource use^[3].

SDG 14 implementation planning uses accounting-derived indicators to track progress on marine pollution, ecosystem management, fisheries sustainability, and economic benefits from sustainable ocean use. Physical extent accounts map directly to SDG indicator 14.5.1 (marine protected area coverage). Asset accounts for fish stocks support indicator 14.4.1 (proportion of fish stocks within biologically sustainable levels). Flow accounts for residuals support indicator 14.1.1 (coastal eutrophication and floating plastic debris density). Economic accounts enable assessment of the economic contribution of sustainable fisheries (14.7.1). The role of ocean accounts in supporting SDG 14 monitoring is detailed in Section 3.4^[4].

Integrated coastal management connects land-based pressures to marine outcomes through physical supply and use tables, supporting targeting of interventions to reduce nutrient loading, sediment transport, and other coastal impacts. The SEEA Central Framework enables systematic tracking of residual flows from land-based activities to marine receiving environments^[5]. By spatially attributing pressures to sources and linking them to changes in ecosystem condition, ocean accounts support the identification of priority actions to reduce negative impacts^[6].

Marine Spatial Planning (MSP) has emerged as a leading framework for organizing the spatial allocation of ocean activities. MSP processes typically involve mapping existing uses and conditions, identifying conflicts and compatibilities between different activities, and establishing zones or regulations that govern what activities are permitted in different areas. The effectiveness of MSP depends critically on the availability of coherent, integrated data that can support analysis of trade-offs and synergies across multiple objectives^[7]. Ocean Accounts provide precisely this type of structured information^[8].

3.2 Sustainability indicators from ocean accounts

Three categories of sustainability indicators derived from ocean accounts are particularly relevant for sustainable ocean planning:

Asset change indicators track the stocks and changes in stocks of marine natural capital. These include:

• Changes in ecosystem extent (area of different marine and coastal ecosystem types)
• Changes in ecosystem condition (physical, chemical, biotic, and landscape characteristics)
• Changes in stocks of individual environmental assets (fish biomass, seabed minerals)
• Ecosystem degradation (measured as the decline in expected future ecosystem service flows)

The 2025 SNA establishes that sustainability fundamentally concerns the maintenance of capital stocks necessary for long-term development, and that depletion of natural resources should be treated as a cost of production^[9]. Net Domestic Product (NDP), which deducts both depreciation of produced assets and depletion of natural resources from GDP, is thus conceptually superior to GDP as a measure of economic performance from a sustainability perspective^[10]. Ocean accounts enable the calculation of ocean-specific contributions to these adjusted aggregates, revealing whether ocean-based economic activity is maintaining or eroding the natural capital base.

Ecosystem condition accounts: index structure and reference conditions

For the reference condition options, normalisation formula, and aggregation methods used in ecosystem condition accounts, see TG-2.1 Aggregate Biophysical Indicators of Environmental State and TG-3.1 Asset Accounts Section 3.4.2.

Flow indicators measure the services provided by marine ecosystems and their relationship to economic activity:

• Provisioning services (wild fish biomass harvested, aquaculture production, marine genetic resources)
• Regulating services (coastal protection from storms and erosion, carbon sequestration in blue carbon ecosystems, water purification)
• Cultural services (marine recreation, coastal tourism, cultural and spiritual values)

The SEEA Ecosystem Accounting framework organizes ecosystem services into supply and use tables that reveal which economic sectors benefit from which ecosystem services, and which ecosystem assets supply those services^[11].

Pressure indicators measure the impacts of human activities on marine environments:

• Residual flows (pollution, marine debris, nutrient loading)
• Resource extraction rates relative to regeneration capacity
• Physical disturbance to marine habitats
• Climate-related pressures (ocean warming, acidification, sea level rise)

The SEEA Central Framework provides the structure for recording these physical flows between the economy and the environment through Physical Supply and Use Tables (PSUTs)^[12]. By spatially attributing pressures to sources and linking them to changes in ecosystem condition, ocean accounts support the identification of priority actions to reduce negative impacts.

The following table summarizes how indicators from different account types link across environmental, economic, social, and governance domains, and how each connects to specific SDG 14 targets.

Table 3.2.1: Indicator-account linkage across sustainability domains

For interim MPA coverage calculations, compilers should use UNEP-WCMC/IUCN WDPA data^[13].

Downward connections to accounts and indicators

Sustainable ocean planning requires specific accounts and indicators to inform decision processes. The following table maps planning use cases to the accounts that should be compiled and the indicators that should be derived:

Table 3.2.2: Planning use cases and required accounts

This table provides compilers with a roadmap for prioritizing account compilation based on the planning processes active in their country. For example, a country developing its first SDG 14 Voluntary National Review should prioritize extent accounts (for MPA coverage), asset accounts for aquatic resources (for fish stock sustainability), and ocean economy accounts (for economic contribution indicators).

3.3 Balancing economic and environmental objectives

A core function of sustainable ocean planning is to navigate trade-offs between economic objectives and environmental protection. Ocean accounts support this by providing integrated information that allows decision-makers to assess how different choices affect both domains simultaneously. The extended balance sheet approach, which records both produced assets (ports, vessels, coastal infrastructure) and natural capital (ecosystem assets, fish stocks, seabed resources) within a consistent valuation framework, enables comprehensive assessment of ocean wealth. As the 2025 SNA establishes, natural capital comprises natural resources (recognized within the integrated framework of national accounts) and ecosystem assets (measured through SEEA Ecosystem Accounting)^[14]. Changes in this comprehensive ocean balance sheet reveal whether development is increasing overall wealth or converting natural capital into produced capital—or worse, depleting natural capital without corresponding gains.

The ecosystem degradation concept provides a monetary measure of the cost of environmental decline. Degradation is defined as the decline in the expected future ecosystem service flows attributable to human activity during an accounting period^[15]. By measuring degradation in monetary terms consistent with national accounts, planners can assess the full costs of development pathways that damage marine ecosystems.

Illustrative two-step degradation calculation: As a simplified illustration, consider a coastal mangrove ecosystem providing USD 800,000/yr in coastal protection services. A decline in mangrove condition reduces that service flow by USD 100,000/yr. At a discount rate of 5%, capitalising this annual loss over the remaining asset life (say 30 years) yields a degradation charge of approximately USD 1.5 million—representing the present value of foregone protection services attributable to the condition decline. The full methodology requires specialist expertise in ecosystem service valuation and may require collaboration with environmental economists for first compilations. Detailed compilation guidance is deferred to a dedicated TG circular. See also SEEA-EA Chapter 10 and TG-3.1 Asset Accounts for asset valuation methodology^[16].

Practical application of this balancing function involves several steps, summarised in Table 3.3.0 below.

Table 3.3.0: Steps in applying ocean accounts to balance economic and environmental objectives

The accounting framework ensures that these assessments maintain internal consistency. Because all components are linked through supply-use relationships and stock-flow identities, changes projected for one component must be reconciled with changes in related components. This discipline prevents the optimistic assumptions that can otherwise undermine planning processes.

Dashboard approach for ocean sustainability monitoring

An effective approach to presenting integrated sustainability information is the ocean sustainability dashboard—a set of headline indicators spanning economic, environmental, and social dimensions that can be tracked over time and compared against targets. Table 3.3.1 presents an illustrative dashboard structure populated with synthetic data.

Table 3.3.1: Ocean sustainability dashboard (Country A, illustrative)

The dashboard reveals that while economic indicators are on track to meet targets, environmental and pollution indicators are lagging. This pattern suggests that economic growth is occurring at the expense of natural capital depletion—a finding confirmed by the gap between gross ocean GVA (3.5%) and net ocean GVA adjusted for depletion (3.3%). The dashboard structure enables presentation to cabinet-level decision-makers and supports integrated policy responses that address economic, environmental, and social dimensions simultaneously. This approach draws on the combined presentation principles described in TG-3.8 Combined Presentations, which provides detailed guidance on assembling multi-dimensional indicator sets from ocean accounts.

3.4 Integration with SDG monitoring

SDG 14 ("Conserve and sustainably use the oceans, seas and marine resources for sustainable development") establishes a global framework for ocean sustainability with specific targets and indicators^[18]. Ocean accounts provide a structured basis for producing many of these indicators and for understanding the relationships between them.

Key SDG 14 targets and their connection to ocean accounts include:

SDG 14 monitoring and ocean accounts

Sustainable Development Goal 14 encompasses ten targets and eleven indicators covering marine pollution, ecosystem management, ocean acidification, fisheries sustainability, marine protected areas, small-scale fisheries, marine research, and UNCLOS implementation^[19]. As of 2024, all SDG 14 indicators have an established methodology (Tier I or II), although data coverage remains uneven across regions and indicators^[20]. Significant data gaps persist—particularly for small island developing states and developing countries, and for targets relating to marine pollution (SDG 14.1), subsidies (SDG 14.6), and economic benefits to SIDS and LDCs (SDG 14.7)^[21].

Ocean accounts provide a systematic framework for generating data that supports SDG 14 monitoring. Physical extent accounts map directly to indicator 14.5.1 (marine protected area coverage). Asset accounts for fish stocks support indicator 14.4.1 (proportion of fish stocks within biologically sustainable levels). Flow accounts for residuals support indicator 14.1.1 (coastal eutrophication and floating plastic debris density). Economic accounts enable assessment of the economic contribution of sustainable fisheries (14.7.1). Rather than addressing each indicator in isolation through bespoke data collection efforts, the accounting approach provides an integrated information system from which a range of indicators can be drawn.

The Kunming-Montreal Global Biodiversity Framework (GBF), adopted in December 2022, establishes complementary targets relevant to ocean accounting, including Target 3 (30% of marine areas effectively conserved by 2030), Target 5 (sustainable harvesting of wild species), and Target 10 (sustainable management of areas under agriculture, aquaculture, and forestry)^[22]. Ocean accounts can generate indicators aligned with both SDG 14 and GBF targets, and the shared data foundations required for monitoring both frameworks reinforce the case for investment in comprehensive ocean accounting.

Beyond SDG 14, ocean accounts support monitoring of other SDGs that intersect with ocean sustainability. SDG 2 (Zero Hunger) targets benefit from accounts that track fish provisioning and aquaculture production. SDG 8 (Decent Work and Economic Growth) targets can draw on ocean economy thematic accounts that measure employment and value added in ocean sectors. SDG 13 (Climate Action) targets connect to accounts measuring blue carbon stocks and sequestration services^[23].

National ocean accounts provide the macro-level reference data against which corporate biodiversity disclosures can be benchmarked; guidance on aligning ocean accounts with private sector reporting frameworks (including GBF Target 15 and the Taskforce on Nature-related Financial Disclosures) is addressed in a forthcoming TG circular on private sector engagement.

3.5 Planning frameworks and ocean accounts

Ocean accounts integrate with various planning frameworks that guide ocean governance. This section describes how accounting information flows into and supports specific planning processes.

Marine Spatial Planning

MSP processes require data on current uses, environmental conditions, and the compatibility of different activities. Ocean accounts contribute:

• Spatial data on ecosystem extent and condition organized by Basic Spatial Units (BSUs)
• Economic data on the location and intensity of ocean-related activities
• Service flow data revealing dependencies of economic activities on ecosystem condition
• Pressure data identifying sources and pathways of environmental impacts

The systematic organization of these data within the ocean accounts framework supports the GIS-based overlay analysis that is central to MSP. Planners can interrogate which areas face multiple pressures, which economic activities depend on ecosystem services supplied from specific locations, and where conservation measures would yield the greatest benefits^[24].

Integrated Coastal Management

Integrated coastal management addresses the land-sea interface where many ocean sustainability challenges originate. Ocean accounts support integrated coastal management by:

• Linking terrestrial and marine BSUs to trace land-based sources of marine pollution
• Connecting coastal ecosystem condition to upstream pressures
• Measuring the coastal protection services that natural ecosystems provide
• Tracking changes in coastal land cover and its implications for marine environments

The physical supply and use structure of the SEEA Central Framework enables systematic tracking of residual flows from land-based activities to marine receiving environments^[25].

Compiling accounts that span the land-sea interface requires harmonising Basic Spatial Units (BSUs) across terrestrial and marine domains. The recommended approach is drainage basin allocation: identify the sub-catchments draining to each coastal BSU, then apportion terrestrial pressures (nutrient loading, sediment, pollutants) to marine receiving BSUs using a hydrological weighting factor derived from relative catchment area and runoff volume. GIS intersection is the standard technical method for this attribution. For first compilations, a simplified approach—mapping coastal watershed polygons to the nearest marine BSU—is acceptable. BSU design should match the resolution of available data; no fixed resolution is prescribed. See ESCAP (2021) Ocean Accounts: Piloting the SEEA EEA for the Ocean, Chapter 3, and SEEA-EA paras 3.29--3.44 for detailed spatial framework guidance^[26].

Fisheries Management

Fisheries management requires information on stock status, extraction rates, and the ecosystem context of target species. Ocean accounts contribute:

• Asset accounts for aquatic resources providing stock estimates and sustainable yield calculations
• Depletion measures indicating whether extraction exceeds natural regeneration
• Ecosystem condition data relevant to recruitment success and stock productivity
• Economic data on fishing industry structure and performance

The SEEA Central Framework establishes the accounting treatment for aquatic resources, distinguishing between cultivated (aquaculture) and natural (wild-capture) biological resources and providing guidance on stock measurement and depletion accounting^[27].

Blue Economy Development

Blue economy strategies seek to expand ocean-based economic activity while maintaining environmental sustainability. Ocean accounts inform blue economy planning by:

• Quantifying current contributions of ocean sectors to GDP, employment, and trade
• Measuring dependencies of economic sectors on ecosystem services
• Identifying opportunities for growth in sustainable ocean sectors
• Assessing whether current development trajectories maintain or erode natural capital

Ocean economy thematic accounts, structured according to SNA principles, provide the foundation for blue economy assessment^[28]. See also TG-2.5 Structure and Function of the Ocean Economy for blue economy account compilation guidance.

Climate Adaptation Planning

Coastal and marine areas face significant climate risks including sea level rise, ocean warming, acidification, and increased storm intensity. Ocean accounts support climate adaptation by:

• Measuring blue carbon stocks and sequestration services
• Tracking ecosystem condition indicators sensitive to climate change (coral bleaching, species range shifts)
• Valuing coastal protection services at risk from ecosystem degradation
• Identifying areas and populations most exposed to climate-related hazards

The thematic accounting approach established in SEEA Ecosystem Accounting enables the development of carbon stock accounts that track carbon in different marine and coastal reservoirs^[29]. See also TG-3.1 Asset Accounts for carbon stock account methodology.

3.6 Implementation process for ocean accounts

Implementation process for ocean accounts: lessons from ESCAP pilots

The ESCAP Ocean Accounts Pilot Programme (2019) demonstrated a structured implementation methodology across seven countries—China, Indonesia, Malaysia, Samoa, Thailand, Vanuatu, and Vietnam. The approach used the Diagnostic Tool for Environment Statistics as a framework for guiding a structured conversation among stakeholders to determine which accounts should be prioritized^[30].

The Diagnostic Tool addresses two core components:

Table 3.6.1: Diagnostic Tool components for ocean accounts scoping

Pilots to date have addressed topics including the value of the ocean economy and sustainability of food supply; physical measures of regulating and maintenance services (coastal protection, carbon sequestration, water purification); ecosystem extent and change (e.g., decline in mangrove area, increase in marine protected area coverage); land-based sources of marine pollution; and resource requirements of coastal tourism. The following table illustrates the types of pilot topics selected across the ESCAP programme:

Table 3.6.2: ESCAP pilot topics and associated policy concerns

The scoping phase typically involved an independent consultant, the National Statistical Office, or a responsible government agency coordinating a detailed scoping report. Most pilots identified data availability and access as major constraints and addressed these by using publicly available data, establishing data sharing arrangements with relevant institutions, or conducting original fieldwork and socio-economic surveys. A second national workshop reviewed preliminary results, benefited from additional technical guidance, and developed messaging for a release document. The process was followed in all seven ESCAP pilots, which demonstrated substantial results within an approximately six-month timeframe^[31].

Case illustration: Vietnam ESCAP Pilot (Quang Ninh Province, 2019)

The 2019 ESCAP ocean accounts pilot for Vietnam integrated UNEP-WCMC global data on coral reefs and seagrasses with local data on mangroves, ports, and marine protected areas to assess ecosystem extent changes in Quang Ninh Province. The pilot overlaid multiple spatial datasets from different institutions within a common spatial framework to produce an initial physical ecosystem extent account, demonstrating how disparate datasets can be combined to reveal relationships between port development, shipping routes, protected area coverage, and changes in mangrove, coral, and seagrass extent^[32].

The Vietnam pilot illustrates a broader finding from the ESCAP programme: initial ocean accounts can be compiled by integrating existing data from multiple sources within a common spatial and classificatory framework, rather than requiring substantial new data collection. The scoping reports produced by each pilot country have been published by ESCAP and provide detailed documentation of the diagnostic process, data sources used, and accounts compiled^[33].

Prioritising account types: a decision framework

When capacity allows only one or two pilot topics, countries can use the following decision matrix to align account type selection with the policy context driving demand. The matrix is a recommended starting point, not a mandatory decision rule; the ESCAP Diagnostic Tool and Table 3.2.2 provide complementary guidance.

Table 3.6.3: Policy context and recommended first-priority account types

Countries with limited capacity should consider extent accounts as the lowest-cost, highest-data-availability starting point: area data for major ecosystem types can typically be compiled from existing remote sensing products and protected area registries without primary data collection. Cross-reference Table 3.2.2 and the ESCAP Diagnostic Tool for further context-specific guidance.

3.7 Worked example: Ocean sustainability dashboard

To demonstrate the practical application of ocean accounts to sustainable ocean planning, this section presents a synthetic worked example showing how account-derived indicators populate an ocean sustainability dashboard for decision-makers. The example uses hypothetical data for a medium-sized coastal state developing a five-year sustainable ocean economy roadmap.

Scenario

Country B is a middle-income coastal state with an ocean economy contributing 4.2% of GDP and employing 380,000 people. The government is developing a sustainable ocean economy roadmap for 2025-2030 that aims to increase the ocean economy's GDP contribution to 5.5% while ensuring fish stocks are rebuilt to sustainable levels and coastal ecosystems are protected. The Ministry of Finance requires quantified evidence that the proposed roadmap maintains natural capital and does not rely on unsustainable resource depletion.

Account compilation

The National Statistics Office compiled the accounts summarised in Table 3.7.0 below for baseline year 2024. The asset account for aquatic resources records opening biomass of 165,000 tonnes, natural growth of 32,000 tonnes, natural mortality of 13,000 tonnes, net natural change of 19,000 tonnes, actual catch of 32,000 tonnes/yr, and closing stock of 152,000 tonnes; sustainable yield is 28,000 tonnes/yr, implying depletion of 4,000 tonnes/yr.

Table 3.7.0: Baseline accounts compiled for Country B (2024)

Indicator derivation

From these accounts, the following sustainability indicators were derived for the dashboard:

Table 3.7.1: Baseline sustainability indicators for Country B (2024)

Scenario projections

The sustainable ocean economy roadmap proposes three intervention packages, each with projected effects on economic and environmental indicators. The projections use the accounting identities to ensure internal consistency: changes in fish stock biomass are reconciled with extraction and growth rates; changes in ecosystem extent affect service flows; changes in condition affect service capacity.

Table 3.7.2: Scenario projections for 2030 target year

Scenario A (Business as usual): Continuation of current policies results in increased ocean GVA but continued depletion of fish stocks (depletion rising to 6,000 tonnes/yr), declining mangrove extent (−50 km²), and worsening coral condition. Net ocean GVA grows more slowly than gross GVA due to increased depletion costs, signaling unsustainability.

Scenario B (Moderate intervention): Implementation of catch limits at sustainable yield (28,000 tonnes/yr), mangrove restoration (+40 km²), and wastewater treatment upgrades reducing nitrogen loading by 18%. Ocean GVA reaches 5.2% of GDP, fish stocks recover fully to the MSY biomass target (195,000 tonnes) by 2030, and net ocean GVA growth matches gross growth (no depletion). The "fish stocks at sustainable levels" indicator is Achieved under Scenario B: the stock returns to the MSY biomass target, and catch is at or below sustainable yield throughout the projection period^[36]. This scenario meets most 2030 targets.^[37]

Scenario C (Strong conservation): More aggressive interventions including marine protected area expansion, larger restoration programmes, and stronger pollution controls. Environmental indicators exceed targets (fish stock biomass reaches 210,000 tonnes, above the 195,000 t MSY target), but ocean GVA growth is slightly constrained (5.0% vs 5.5% target) due to spatial allocation of 15% of fishing grounds to no-take MPAs. The additional stock recovery in Scenario C reflects enhanced recruitment from no-take zones and reduced bycatch mortality, projected using a spatial population model.

Note on scenario modelling levels: The accounting-based scenario projections in Scenarios A and B can be implemented using stock identity accounting—opening stock + net natural change − catch = closing stock—and do not require specialist fisheries modelling. The spatial population model referenced in Scenario C requires collaboration with fisheries scientists and is presented for completeness, not as a minimum requirement for compilers. For practitioners who wish to pursue Scenario C-level analysis, see FAO (1999) Guidelines for the routine collection of capture fishery data^[38] and ICES (2021) stock assessment guidance^[39].

Dashboard presentation

The scenario analysis was presented to cabinet in Table 3.7.3, showing the trade-offs between economic growth and environmental outcomes:

Table 3.7.3: Sustainable ocean economy roadmap dashboard (Country B)

Policy implications

The analysis demonstrated that:

1. Gross GVA overstates sustainability: The gap between gross and net ocean GVA (4.2% vs 4.18% in 2024, widening to 4.8% vs 4.3% under business-as-usual in 2030) reveals that current growth relies on natural capital depletion. This finding, grounded in the 2025 SNA treatment of depletion as a production cost, provided compelling evidence for the finance ministry that current policies are unsustainable.

2. Catch limits enable rebuilding: Scenario B shows that reducing catch to sustainable yield (28,000 tonnes/yr) allows fish stocks to recover from 152,000 tonnes to the MSY biomass target of 195,000 tonnes over six years, even while maintaining a productive fishery. This reverses the depletion recorded in asset accounts and eliminates the NDP adjustment, demonstrating that conservation measures can align economic and environmental objectives.

3. Restoration investments yield long-term returns: The mangrove restoration component of Scenario B (+40 km² by 2030) costs an estimated USD 15 million over six years but generates coastal protection services valued at USD 480,000/yr (replacement cost basis) and carbon sequestration services valued at USD 160,000/yr, providing annual service flows of USD 640,000. The undiscounted breakeven point is approximately year 23 (USD 15,000,000 ÷ USD 640,000/yr ≈ 23.4 years). Practitioners should apply their country's social discount rate when replicating this analysis; blue carbon values may increase as carbon prices rise, strengthening the net benefits case over time^[40]. These service flows are recorded in ecosystem service accounts (TG-3.2).

4. Pollution controls support ecosystem recovery: The 18% reduction in nitrogen loading under Scenario B (from 12,400 to 10,200 tonnes/yr), achieved through wastewater treatment upgrades costing USD 22 million, improves water quality sufficiently to support coral and seagrass condition improvement. The condition improvements are projected to increase ecosystem service capacity by 8%, yielding fishery nursery benefits that partially offset the costs of pollution controls.

Based on this analysis, the cabinet approved Scenario B as the basis for the sustainable ocean economy roadmap, with specific budget allocations for catch management enforcement, mangrove restoration, and wastewater infrastructure documented in the national budget presentation (TG-1.1 OA and National Budget Processes).

4. Acknowledgements

This Circular has been approved for public circulation and comment by the GOAP Technical Experts Group in accordance with the Circular Publication Procedure.

Authors: [To be confirmed]

Reviewers: [To be confirmed]

5. References