Overview of Relevant Statistical Standards

1. Outcome

This Circular provides a comprehensive overview of the international statistical standards that underpin Ocean Accounts, establishing the methodological foundations on which the Technical Guidance is built. Readers will gain an understanding of how the System of National Accounts 2025 (SNA 2025), the System of Environmental-Economic Accounting Central Framework (SEEA CF), and SEEA Ecosystem Accounting (SEEA EA) collectively provide the accounting architecture for measuring ocean-economy-society interactions.

Understanding these standards enables critical policy applications. When governments prepare national ocean budgets (TG-1.1 OA and National Budget Processes), they rely on ocean economy statistics compiled following SNA 2025 principles--gross value added, employment, trade, and fish protein supply--to demonstrate the sector's contribution to national income and justify public investment in ocean management. When compiling asset accounts for marine natural resources (TG-3.1 Asset Accounts), compilers apply SEEA CF guidance on physical depletion (catch exceeding sustainable yield) and monetary valuation (net present value of resource rents), translating stock assessment data into balance sheet entries that reveal whether fisheries extraction is sustainable. When measuring ecosystem services from coastal ecosystems (TG-2.4 Ecosystem Goods and Services), analysts use SEEA EA's spatial accounting framework to quantify mangrove carbon sequestration, coral reef coastal protection, and seagrass nursery habitat services, supporting policy decisions on marine protected area design and blue carbon finance.

The Circular introduces the emerging ocean accounting framework being developed within the SEEA family of standards, and identifies the international classification systems essential for compiling consistent and comparable ocean accounts. By understanding these foundational standards, readers will be equipped to interpret the detailed methodological guidance provided in subsequent Circulars and to situate their accounting work within the broader international statistical architecture. Key terms introduced here are defined in TG-0.6 Glossary.

2. Requirements

This Circular requires familiarity with:

• TG-0.1 General Introduction to Ocean Accounts -- for the conceptual framework and key components of Ocean Accounts, including the relationship between environmental and economic accounting frameworks and the spatial boundaries relevant to ocean accounting.

3. Guidance Material

The international statistical standards described in this Circular form a coherent, hierarchical system. The System of National Accounts (SNA) provides the overarching framework for economic accounting, while the System of Environmental-Economic Accounting (SEEA) extends this framework to measure interactions between the economy and the environment. Within the SEEA family, the Central Framework addresses individual environmental assets and physical flows, while SEEA Ecosystem Accounting provides methodology for measuring ecosystems as integrated spatial units. Ocean Accounts build upon all these standards, adapting their concepts and methods to the marine and coastal domain.

This section examines each standard in turn, highlighting its relevance to ocean accounting and the specific methodological guidance it provides. For guidance on data quality considerations applicable across all ocean accounting work, see TG-0.7 Quality Assurance.

Figure 0.2.1: Statistical standards framework hierarchy^[1]

3.1 System of National Accounts 2025

The System of National Accounts (SNA) is the internationally agreed set of standards for measuring economic activity. It provides the conceptual framework, classifications, and accounting rules that countries use to compile their national accounts statistics, including measures such as Gross Domestic Product (GDP). The 2025 SNA, adopted by the United Nations Statistical Commission at its 56th session in March 2025, represents a significant update that strengthens linkages with environmental accounting and introduces new concepts directly relevant to ocean accounts^[2].

The SNA defines a "whole set of standards, including extended/thematic accounts and supplementary items"^[3]. At its core is the integrated framework of national accounts, which consists of the sequence of economic accounts (recording flows between institutional sectors), supply and use tables (showing how products flow through the economy), and balance sheets (recording stocks of assets and liabilities)^[3:1]. This integrated framework provides the foundation upon which environmental accounts--including ocean accounts--are constructed.

Key concepts for ocean accounting

The SNA 2025 provides several concepts that are foundational for ocean accounting applications. The integrated framework of national accounts consists of the sequence of economic accounts, supply and use tables, labour market tables, and the table on capital services^[3:2]. When compiling ocean economy thematic accounts (TG-3.3 Economic Activity Relevant to the Ocean), compilers extract ocean economy sub-matrices from these integrated tables, following the same accounting identities and valuation principles that ensure the national accounts balance.

The sequence of economic accounts records the production of goods and services, the generation, distribution and redistribution of income, the use of income for consumption or saving, and capital accumulation, culminating in balance sheets showing stocks of assets and liabilities^[4]. For the ocean economy, this sequence enables measurement of gross value added by ocean industries (fishing, aquaculture, maritime transport, offshore energy), flows of income to households employed in ocean sectors, government expenditure on fisheries management and marine environmental protection, and investment in ocean infrastructure.

Treatment of natural resources

A key advance in the 2025 SNA is the explicit recognition of natural resources as a separate category within the asset classification, with renewable energy resources now also explicitly recognised^[5]. The SNA identifies five categories of natural resources: land, mineral and energy resources, biological resources, water resources, and other natural resources^[2:1]. For ocean accounting, this classification encompasses seabed minerals, offshore energy resources (including renewable sources such as offshore wind and tidal energy), aquatic biological resources such as fish stocks, and coastal land.

The 2025 SNA introduces the concept of natural capital, defined as "the combination of natural resources and ecosystem assets"^[6]. This definition bridges the SNA's treatment of individual natural resources with the ecosystem approach taken in SEEA Ecosystem Accounting, providing important conceptual coherence for ocean accounts that must measure both individual marine assets (such as fish stocks) and marine ecosystems (such as coral reefs or seagrass meadows). The treatment of natural capital in ocean contexts is applied in TG-3.1 Asset Accounts, which demonstrates how fish stock asset accounts (SEEA CF) and coral reef ecosystem asset accounts (SEEA EA) are compiled using complementary but consistent methodologies that can be aggregated into a comprehensive natural capital balance sheet for ocean domains.

Depletion as a cost of production

The 2025 SNA treats depletion of natural resources as a cost of production, alongside the depreciation of produced assets^[7]. This treatment has significant implications for ocean accounting. When fish stocks are harvested beyond sustainable levels, the resulting depletion is recorded as a cost that reduces net measures of production. The SNA now emphasises that "the volume change of net domestic product (NDP) is identified as the conceptually preferred measure of economic growth, not replacing but to be used alongside the volume change of gross domestic product (GDP)"^[7:1]. This shift toward net measures provides stronger signals about the sustainability of ocean-based economic activities.

Concrete application: When compiling structural indicators for the ocean economy (TG-2.5 Structure and Function of the Ocean Economy), analysts calculate Net Ocean GVA by subtracting depletion of marine natural resources from Gross Ocean GVA. If a coastal state reports Gross Ocean GVA of USD 1,750 million but fish stock depletion of USD 35 million and offshore mineral depletion of USD 60 million, Net Ocean GVA is USD 1,655 million--revealing that 5.4% of the ocean economy's recorded gross contribution depends on drawing down natural capital. This measure directly informs medium-term expenditure frameworks in national ocean budgets (TG-1.1 Section 3.4), signalling to budget officials that current economic gains from ocean sectors may not be sustainable without investment in fisheries management and conservation.

Production boundary and natural processes

The SNA establishes clear criteria for what constitutes economic production. A necessary condition is that the activity "must be carried out under the instigation, control and responsibility of some institutional unit that exercises ownership rights over whatever is produced"^[8]. This criterion has important implications for ocean accounting. The growth of fish in aquaculture facilities is treated as production (analogous to livestock rearing), while the natural growth of wild fish stocks in international waters not subject to management is not counted as production^[8:1]. The SNA notes that "the natural growth of non-cultivated biological resources, such as fish stocks under a quota regime, may take the form of fish becoming more numerous. Although these resources are economic assets, growth of this kind is not under the direct control, responsibility and management of an institutional unit and thus is not treated as production"^[9].

This boundary has operational consequences for compiling ocean economy GDP statistics. Aquaculture production is included in ocean economy gross value added and contributes to the output of ISIC Division 03 (Fishing and Aquaculture) reported in TG-3.3. Natural growth of wild fish stocks, by contrast, is not production but is recorded as an addition to stock in the physical asset account in TG-3.1 Table 7, where it is offset against extraction (catch) and natural mortality to calculate changes in fish stock biomass.

Asset boundary

Natural resources are included in the SNA's balance sheets "provided that institutional units are exercising effective ownership rights over them, that is, are actually in a position to be able to benefit from them"^[10]. For ocean accounting, this means that resources within a country's Exclusive Economic Zone (EEZ) are generally within scope, as the coastal state exercises sovereign rights over these resources. However, resources in the high seas "over which no ownership rights can be exercised" are excluded from the asset boundary^[10:1]. The SNA explicitly notes that ecosystem assets are excluded from the integrated framework but recommends compilation of ecosystem accounts according to SEEA Ecosystem Accounting^[11].

For resources in areas beyond national jurisdiction (ABNJ), the Agreement under the United Nations Convention on the Law of the Sea on the Conservation and Sustainable Use of Marine Biological Diversity of Areas beyond National Jurisdiction (BBNJ Agreement), which entered into force on 17 January 2026, may provide new frameworks for accounting treatment as its governance structures develop^[12]. Compilers should note that the BBNJ Agreement establishes new institutional arrangements for marine genetic resources, area-based management tools, environmental impact assessments, and capacity-building in ABNJ, which may over time clarify the institutional attribution of benefits from high seas resources and thus inform asset accounting boundaries. Guidance on deep-sea and ABNJ accounting is provided in TG-6.6 Deep-Sea and ABNJ.

Linkage with SEEA

The 2025 SNA "strengthens the linkages with the System of Environmental Economic Accounting (SEEA) as an important framework that is complementary to and aligned with the SNA"^[5:1]. The SNA describes the SEEA as providing "a comprehensive set of monetary and non-monetary accounts covering natural resources and ecosystem assets"^[13] and "strongly encourages" the compilation of ecosystem accounts according to SEEA Ecosystem Accounting^[11:1]. The 2025 SNA also explicitly identifies ocean accounting as an application of its thematic accounting framework^[2:2].

Concrete application: The SNA's thematic accounting framework (SNA 2025 Chapter 38) provides the methodological basis for compiling ocean economy accounts as a cross-cutting segment of the national economy. When preparing the ocean economy thematic supply and use tables described in TG-3.3 Section 3.4, compilers follow the SNA 2025 guidance on identifying ocean-characteristic industries (ISIC Division 03 Fishing and aquaculture, ISIC Division 50 Water transport, offshore portions of ISIC Division 06 Extraction of crude petroleum and natural gas) and ocean-characteristic products (CPC Division 04 Fish and fishing products, CPC Division 65 Water transport services), extracting these from the national supply and use tables while maintaining the accounting identities (output = intermediate consumption + final demand + exports - imports) that ensure internal consistency.

3.2 SEEA Central Framework

The SEEA Central Framework (SEEA CF) is "a multipurpose conceptual framework that describes the interactions between the economy and the environment, and the stocks and changes in stocks of environmental assets"^[14]. Adopted as an international statistical standard in 2012, the SEEA CF extends the SNA's economic accounts to systematically record physical flows between the environment and the economy, and to measure stocks of individual environmental assets. An update to the SEEA CF is currently underway, with adoption anticipated in March 2028, to ensure alignment with the 2025 SNA^[15].

Environmental assets

The SEEA CF defines environmental assets as "the naturally occurring living and non-living components of the Earth, together constituting the biophysical environment, that may provide benefits to humanity"^[16]. These assets are classified into seven main categories: mineral and energy resources; land; soil resources; timber resources; aquatic resources (including wild fish and aquaculture); other biological resources; and water resources^[17]. For ocean accounting, the aquatic resources category is particularly important, encompassing both cultivated aquatic resources (aquaculture) and natural aquatic resources (wild fish, crustaceans, molluscs, and aquatic plants)^[18].

The SEEA CF explicitly includes resources within a country's Exclusive Economic Zone. It states that "the SEEA Central Framework includes all natural resources, cultivated biological resources and land within a country of reference (including resources within a country's exclusive economic zone)"^[19]. However, the scope for high seas resources is more limited: "While some aquatic resources on the high seas are included as part of individual environmental assets (e.g., fish stocks attributable to countries on the basis of international agreements on access rights), the overall scope of the asset boundary in the SEEA Central Framework is narrower"^[20].

Physical flow accounts

The SEEA CF provides a detailed framework for measuring physical flows between the environment and the economy. All flows from the environment to the economy fall under the heading of natural inputs, which include natural resource inputs, inputs of energy from renewable sources, and other natural inputs^[21]. The Physical Supply and Use Tables (PSUTs) record these flows in physical units (tonnes, cubic metres, joules), providing a complement to the monetary supply and use tables of the SNA.

For ocean accounting, the physical flow accounts enable measurement of: fish catches and other aquatic harvests; extraction of seabed minerals and energy resources; use of marine water; and inputs of marine renewable energy (wind, wave, tidal). The SEEA CF also provides frameworks for recording residual flows--emissions and waste returned to the environment--which are critical for understanding pressures on marine ecosystems from pollution.

Concrete application: When compiling physical flow accounts for a coastal region (TG-3.2 Flows from Environment to Economy), compilers populate a Physical Supply and Use Table with rows for natural aquatic resources (measured in tonnes), offshore oil and gas (measured in barrels of oil equivalent), and marine renewable energy (measured in joules). The Supply Table shows gross catch of demersal fish (24,000 tonnes) supplied from the environment, while the Use Table shows intermediate consumption of fish by fish processing industries (5,000 tonnes) and final consumption by households (19,000 tonnes). This physical accounting provides the foundation for deriving sustainability indicators: if the sustainable yield estimate is 22,000 tonnes but gross catch is 24,000 tonnes, the physical accounts signal that extraction exceeds regeneration by 2,000 tonnes--a measure of physical depletion that is then valued in monetary terms in the asset accounts.

Asset accounts structure

Asset accounts in the SEEA CF record the opening stock of an environmental asset at the beginning of an accounting period, additions and reductions during the period, and the closing stock^[22]. For aquatic resources, additions include natural growth (recruitment and biomass increase), while reductions include catches (extractions), natural mortality, and catastrophic losses. The SEEA CF introduces the concept of physical depletion as "the decrease in the quantity of the stock of a natural resource over an accounting period that is due to the extraction of the natural resource by economic units occurring at a level greater than that of regeneration"^[23].

The treatment of discards is also addressed: "During the extraction of some natural resource inputs, not all extraction is retained in the economy, for example, in fishing operations, there is an amount of discarded catch"^[24]. This guidance is directly relevant for fisheries accounting where discards can represent a significant portion of total catch. Detailed methodological guidance for asset accounts is provided in TG-3.1 Asset Accounts.

Aquaculture versus wild capture

The SEEA CF maintains a clear distinction between cultivated and natural biological resources. "All cultivated biological resources are considered to be within the production boundary"^[25], meaning that aquaculture production is treated similarly to agricultural production. In contrast, natural biological resources (including wild fish) "are recorded as entering the economy at the point of harvest"^[26]. This distinction has fundamental implications for how changes in fish stocks are recorded--changes in aquaculture stocks are recorded as changes in produced assets, while reductions in wild fish stocks through overfishing constitute depletion of natural resources.

Concrete application: In the comprehensive physical asset account template presented in TG-3.1 Table 1a, cultivated aquatic resources (aquaculture) and natural aquatic resources (wild fish) are shown in separate columns. For cultivated resources, the opening stock of 12,000 tonnes increases through growth in stock (3,500 tonnes) and reclassifications from natural resources (200 tonnes of stocked juveniles), then decreases through harvest (3,200 tonnes) and normal losses (400 tonnes), yielding a closing stock of 12,100 tonnes. For natural resources, the opening stock of 180,000 tonnes increases through natural growth (28,000 tonnes) and discoveries (5,000 tonnes of upward stock reappraisal), then decreases through gross catch (24,000 tonnes), natural mortality (15,000 tonnes), and catastrophic losses (2,000 tonnes from a hypoxia event), yielding a closing stock of 171,000 tonnes. The derived entry shows sustainable yield of 22,000 tonnes, so depletion equals gross catch minus sustainable yield: 24,000 - 22,000 = 2,000 tonnes.

Limitations for marine ecosystems

While the SEEA CF provides comprehensive guidance for individual environmental assets, it does not treat the ocean itself as an environmental asset. The framework "does not include oceans and the atmosphere as part of environmental assets, since their stocks are too large to be meaningful for analytical purposes"^[20:1]. Similarly, marine ecosystems as integrated spatial units are outside the scope of the SEEA CF--for this, SEEA Ecosystem Accounting is required. The SEEA CF also does not specifically address coral reefs, mangroves, seagrass meadows, or other marine ecosystem types; these are covered in SEEA Ecosystem Accounting.

3.3 SEEA Ecosystem Accounting

SEEA Ecosystem Accounting (SEEA EA) was adopted by the United Nations Statistical Commission in March 2021 "as an international statistical standard for the ecosystem accounting framework and physical ecosystem accounts, and presents internationally recognized statistical principles and recommendations for the valuation of ecosystem services and assets"^[27]. The SEEA EA extends the SEEA CF by treating ecosystems as integrated spatial units--ecosystem assets--that can be measured in terms of their extent, condition, and the services they provide.

Core concepts

The SEEA EA defines an ecosystem as "a dynamic complex of plant, animal and micro-organism communities and their non-living environment interacting as a functional unit"^[28], drawing on the definition in the Convention on Biological Diversity. An ecosystem asset is the statistical representation of this concept: "contiguous spaces of a specific ecosystem type characterized by a distinct set of biotic and abiotic components and their interactions"^[29]. Each ecosystem asset is assigned to an ecosystem type, which "reflects a distinct set of abiotic and biotic components and their interactions"^[30].

Ecosystem services are defined as "the contributions of ecosystems to the benefits that are used in economic and other human activity"^[31]. They represent flows generated by ecosystems that enter into production of benefits, and are distinguished from the benefits themselves. The SEEA EA distinguishes between final ecosystem services (directly used by economic units or households) and intermediate services (inputs to the supply of other ecosystem services)^[32].

Five types of ecosystem account

The SEEA EA describes five types of ecosystem account^[33]:

1. Ecosystem extent accounts -- record the areas of different ecosystem types and changes in these areas over time
2. Ecosystem condition accounts -- record the quality of ecosystem assets, measured through condition variables and indicators
3. Ecosystem services flow accounts in physical terms -- record the supply and use of ecosystem services in physical units
4. Ecosystem services flow accounts in monetary terms -- record the value of ecosystem services in currency units
5. Monetary ecosystem asset accounts -- record the value of ecosystem assets as natural capital

The Statistical Commission noted that there are "outstanding methodological concerns related to chapters 8 to 11 on valuation"^[34]. Accordingly, while the physical ecosystem accounts in chapters 3 through 7 of the SEEA EA were adopted as a full international statistical standard, the valuation chapters (8 through 11) were adopted at the level of "internationally recognized statistical principles and recommendations"^[27:1]. This distinction is relevant for ocean accounting applications that involve monetary valuation of marine ecosystem services and assets, as the valuation methodologies carry a different level of international endorsement than the physical accounting frameworks.

Concrete application: When compiling ecosystem accounts for a coastal zone, compilers follow the five-account structure described in TG-3.1 Section 3.7 (Worked Example). The extent account (Table 5) records opening extent of 500 km² of mangroves, 200 km² of seagrass, and 15,000 km² of continental shelf waters, tracking conversions from mangroves to aquaculture (-4.0 km²), restoration projects (+2.5 km²), and storm damage (-2.5 km²), yielding closing extent of 496.8 km² mangroves and 199.2 km² seagrass. The condition account (Table 6) records condition variables including mangrove canopy density (declining from 72% to 70%), leaf litter production (declining from 480 to 465 g/m²/yr), and connectivity index (declining from 0.68 to 0.65), signalling ecosystem degradation. The ecosystem services flow accounts quantify coastal protection service (USD 12,000/ha/yr), carbon sequestration (USD 400/ha/yr), and fish nursery service (USD 800/ha/yr), totalling USD 13,200/ha/yr for mangroves. These service flows are then capitalised at a 4% discount rate to derive the monetary ecosystem asset account (Table 8), showing mangrove asset value of USD 165 million declining to USD 163.6 million after accounting for degradation (-USD 1.65 million) and conversions (-USD 1.32 million), partially offset by revaluation from updated coastal protection valuations (+USD 8.25 million).

Marine ecosystem considerations

The SEEA EA provides specific guidance for marine ecosystems. It notes that "marine ecosystems are not concentrated near one surface (i.e. the air-land/water interface) but extend throughout the water column and include the underlying sediment and seabed"^[35]. The recommended approach for delineation is pragmatic: "for marine ecosystems within the continental shelf, it is recommended that ecosystem assets be delineated based on the areas of the different ecosystem types associated with the seabed, for example, seagrass meadows, subtidal sandy bottoms and coral reefs"^[35:1].

The spatial boundary for ecosystem accounting aligns with the SEEA CF: "Consistent with the scope of the SEEA Central Framework, the scope of national jurisdictions for ecosystem accounting should include all ecosystems across the terrestrial, freshwater and marine realms to the boundary of the exclusive economic zone (EEZ)"^[36]. For areas beyond national jurisdiction, the SEEA EA notes that these may be "the focus of regional or international accounting work"^[37].

IUCN Global Ecosystem Typology

The SEEA EA adopts the IUCN Global Ecosystem Typology (GET) as its reference classification for ecosystem types^[38]. The GET divides the biosphere into five core realms (Terrestrial, Subterranean, Freshwater, Marine, and Atmospheric) plus transitional realms that accommodate ecosystems depending on fluxes between contrasting environments^[39]. For ocean accounting, the relevant realms include:

• Marine realm (M) -- with biomes for marine shelves (M1), pelagic ocean waters (M2), deep-sea floors (M3), and anthropogenic marine systems (M4)
• Transitional realms -- including shoreline systems (MT1), supralittoral coastal systems (MT2), anthropogenic shorelines (MT3), brackish tidal systems (MFT1), and semi-confined transitional waters (FM1)

The Marine Shelf biome (M1) encompasses ecosystem functional groups including seagrass meadows, kelp forests, photic coral reefs, shellfish beds and reefs, subtidal rocky reefs, and subtidal sand and mud habitats^[40]. These categories provide the classification framework for marine ecosystem extent accounts.

Concrete application: When applying the IUCN GET to coral reef ecosystem accounts (TG-6.1 Coral Reef Accounts), compilers classify photic coral reefs as ecosystem functional group M1.3 within the Marine Shelf biome (M1). This classification enables compilers to adopt the biome-specific indicative condition variables listed in SEEA EA Table 5.7, which recommends measuring coral cover (structural state B2), calcification rates (functional state B3), water temperature and ocean pH (physical and chemical state A1, A2), and species richness (compositional state B1) as core condition variables for coral reef condition accounts. The GET's hierarchical structure also enables aggregation--extent accounts can report total Marine Shelf extent (summing M1.1 seagrass + M1.3 coral reefs + M1.4 shellfish beds + M1.6 rocky reefs) and total Transitional realm extent (summing MFT1.2 mangroves + MT1.1 rocky shores + MT1.2 sandy beaches), providing nested spatial reporting at ecosystem functional group, biome, and realm levels.

Ecosystem condition measurement

Ecosystem condition is measured using a three-stage approach: presentation of condition variables, derivation of condition indicators, and optional derivation of composite indices^[41]. The SEEA EA links condition to the concept of ecosystem integrity: "the ecosystem's capacity to maintain its characteristic composition, structure, functioning and self-organization over time within a natural range of variability"^[42]. For marine ecosystems, key drivers of condition include bathymetric profile, climate factors (including ocean acidification and temperature), substrate type, ocean circulation, salinity, and human activities^[43].

3.4 SEEA-Oceans (Emerging)

The development of dedicated ocean accounting guidance within the SEEA framework is ongoing. The SEEA EA does not describe a separate "SEEA-Oceans" standard; rather, it describes ocean accounts as a thematic accounting application that builds upon SEEA EA and the SEEA Central Framework^[44]. The ocean accounts framework has been developed through the work of UN-ESCAP and the Global Ocean Accounts Partnership (GOAP), with the UN Statistical Commission commending this work at its 51st session in March 2020^[15:1].

It is important to note that a formal SEEA Ocean standard has not yet been adopted by the United Nations Statistical Commission. The GOAP Technical Guidance provides an interim methodological framework that applies the principles of the SNA 2025, SEEA CF, and SEEA EA to the marine and coastal domain, drawing on the best available international guidance. As the international statistical community continues to develop ocean-specific methodology, this Technical Guidance will be updated to reflect any standards adopted by the Statistical Commission.

Ocean accounts framework

The SEEA EA describes ocean accounts as providing "a broad framework for connecting relevant elements of the SNA, the SEEA Central Framework and SEEA EA in order to harmonize priority ocean data covering economic, ecological, governance and social dimensions"^[44:1]. The framework adds governance, management and technology accounts alongside the environmental and economic accounts derived from SEEA^[45].

Ocean accounts enable measurement of^[46]:

• Changes in ocean ecosystem extent and condition and in associated flows of ecosystem services
• Changes in ocean wealth, including produced assets (e.g., ports) and non-produced assets (e.g., mangroves, coral reefs)
• Ocean-related income and welfare for different groups of people
• Ocean-based economic production (GDP from ocean-related sectors)
• Changes in how oceans are governed and managed

Current status and development

The Global Ocean Accounts Partnership (GOAP), endorsed as a key initiative in the UN Ocean Decade Programme in July 2025, coordinates the development of ocean accounting methodology and supports implementation in member countries^[15:2]. As of 2025, more than 33 countries are undertaking ocean accounting initiatives, with the "Pledge to Advance Ocean Accounts by 2030" garnering support from 19 nations and 7 international organisations^[15:3]. At the Third United Nations Conference to Support the Implementation of Sustainable Development Goal 14 (UNOC3) in Nice in June 2025, the political declaration "Our ocean, our future: united for urgent action" formally recognized ocean accounting as a key mechanism to accelerate action for a sustainable ocean economy^[47].

Several countries have produced pilot ocean accounts that demonstrate the framework's application. Australia has invested in national-scale ocean accounting planning with an initial focus on blue carbon ecosystems (mangroves, saltmarsh, seagrass, kelp)^[15:4]. The Netherlands has published an experimental SEEA Ocean Ecosystem Account for the Dutch North Sea, representing a comprehensive SEEA EA implementation for marine ecosystems^[48]. Costa Rica is developing the world's first integrated ocean account combining environmental, economic, and social data, with its implementation roadmap adopted by the Council for Environmental Accounts in 2025^[15:5].

Challenges for ocean accounting

The SEEA EA acknowledges specific challenges for ocean accounting. Data on the ocean "is more fragmented than data for terrestrial and freshwater ecosystems and the understanding of the ecological and economic connections among marine ecosystems, coastal ecosystems and other ecosystems is less advanced, although the relationship is expected to be highly non-linear"^[49]. Additional challenges include appropriately reflecting the three dimensions of marine areas (depth in addition to area), accurately capturing changes in condition, and addressing transboundary issues for migrating fish stocks and shared ecosystems^[50].

3.5 Related Classification Standards

The compilation of ocean accounts requires the consistent application of international classification standards. These classifications ensure that data are collected, organised, and reported in ways that enable comparison across countries and over time. The key classifications for ocean accounting span economic activities, products, government expenditure, environmental protection activities, and ecosystem types.

International Standard Industrial Classification (ISIC)

The International Standard Industrial Classification of All Economic Activities (ISIC) provides the framework for classifying economic activities^[51]. ISIC Revision 5 was endorsed by the UN Statistical Commission at its 55th session in March 2024 and organises activities into a four-level hierarchy: sections (alphabetic), divisions (2-digit), groups (3-digit), and classes (4-digit)^[52]. Countries are expected to adapt national classifications by 2025 and implement ISIC Rev.5 in statistical programmes from 2027.

For ocean accounting, the most directly relevant ISIC categories include:

• Division 03 (Fishing and Aquaculture) -- encompassing marine fishing, freshwater fishing, marine aquaculture, and freshwater aquaculture^[53]
• Division 50 (Water Transport) -- covering sea and coastal passenger transport, sea and coastal freight transport, and inland water transport^[54]
• Class 5222 (Service activities incidental to water transportation) -- including port operations, navigation, pilotage, and lighthouse activities^[55]

Other ocean-relevant categories are distributed across the classification, including shipbuilding, offshore support activities for petroleum and natural gas extraction, and recreational fishing services^[56]. The processing of fish at land-based plants is classified separately in Division 10 (Food products)^[57]. Compilers should verify that these division and class codes remain consistent in the final published text of ISIC Rev.5, as the transition from Rev.4 may have introduced reclassifications at the detailed class level.

Concrete application: When compiling the ocean economy sector composition indicators presented in TG-2.5 Table 3.1, compilers classify ocean industries using ISIC codes. Marine fishing (ISIC 0311) and marine aquaculture (ISIC 0321) are grouped under "Marine living resources," which together account for 10.0% of ocean economy GVA and 18.0% of ocean employment. Maritime transport (ISIC 5011, 5012) and ports (ISIC 5222, 5224) are grouped under "Maritime transport and ports," accounting for 18.0% of ocean GVA and 12.0% of employment. This ISIC-based classification enables consistent comparison with national industry statistics and international benchmarking against other countries' ocean economy structures.

Central Product Classification (CPC)

The Central Product Classification (CPC) provides the framework for classifying goods and services^[58]. CPC Version 3.0 was endorsed by the UN Statistical Commission at its 55th session in March 2024 and is organised into a five-level hierarchy from sections to subclasses^[59]. CPC 3.0 includes adaptations for digital transformation and green economy elements, aligned with SNA 2025. Each CPC subclass corresponds to specific ISIC classes of industrial origin, enabling linkage between product statistics and industry statistics^[60].

Division 04 (Fish and Other Fishing Products) provides detailed categories for live fish, fresh fish, crustaceans, molluscs, and other aquatic products, with distinctions between wild-caught and farmed products^[61]. Division 21 covers processed fish products. Transport services related to water are classified in Divisions 65 (water transport services) and 67 (port and waterway operation services)^[62]. Compilers should verify that these division codes remain consistent in the final published text of CPC Ver.3.0, as the transition from Ver.2.1 may have introduced reclassifications.

Classification of Functions of Government (COFOG)

The Classification of Functions of Government (COFOG) enables classification of government expenditure by purpose^[63]. COFOG is currently under revision, with adoption expected in March 2028, aligned with the SEEA CF update timeline^[64]. For ocean accounting, COFOG identifies relevant government functions including:

• 04.2.3 (Fishing and hunting) -- covering fisheries management, regulation, licensing, and support for commercial fishing activities^[65]
• 04.5.2 (Water transport) -- covering maritime transport infrastructure and operations^[66]
• Division 05 (Environmental protection) -- with sub-categories applicable to marine environmental protection, including pollution abatement and biodiversity protection^[67]

CEPA and CReMA

The Classification of Environmental Protection Activities (CEPA) and Classification of Resource Management Activities (CReMA) provide detailed categories for environmental expenditure and activities^[68]. CEPA covers activities aimed at preventing, reducing, and eliminating pollution and environmental degradation, while CReMA covers activities aimed at preserving natural resource stocks.

For ocean accounting, relevant CEPA categories include wastewater management (CEPA 2) covering discharge to marine waters^[69]; protection and remediation of soil and water (CEPA 4) which "concerns surface water, groundwater and marine waters" including oil spill cleanup in coastal areas^[70]; and protection of biodiversity and landscapes (CEPA 6) covering marine species and habitat protection, marine protected area management, and fisheries quota enforcement^[71]. CReMA 13A covers production of energy from renewable sources including ocean energy (wave, tidal, thermal)^[72].

IUCN Global Ecosystem Typology

As noted in Section 3.3, the IUCN Global Ecosystem Typology (GET) serves as the reference classification for ecosystem types in SEEA Ecosystem Accounting. For ocean accounting, the GET provides a comprehensive typology of marine and coastal ecosystems organised into realms, biomes, and ecosystem functional groups. The Marine realm alone encompasses 20 ecosystem functional groups across four biomes, from seagrass meadows and coral reefs in the Marine Shelf biome to chemosynthetic-based ecosystems in the Deep Sea Floors biome^[73]. The transitional realms add further categories for shoreline systems, coastal wetlands, mangroves, estuaries, and other coastal ecosystem types^[74].

Cross-classification considerations

These classification systems serve complementary purposes and can be used together in ocean accounting. ISIC identifies ocean-related industries (the producers), CPC identifies ocean-related products (the outputs), COFOG tracks government spending on ocean functions, CEPA/CReMA tracks environmental protection and resource management activities, and IUCN GET provides the ecosystem asset classification. Correspondences between classifications--such as the linkage between CPC subclasses and their ISIC classes of origin--facilitate integrated analysis^[75].

However, certain gaps exist for ocean accounting purposes. ISIC does not separately identify marine mining from land-based mining, offshore renewable energy is not distinctly classified, and marine-specific environmental activities are often combined with terrestrial activities in CEPA and CReMA^[76]. These limitations may require supplementary classification detail for comprehensive ocean accounts.

3.6 Standards Application Summary

Table 3.1 summarises how the international statistical standards described in this Circular are applied across the GOAP Technical Guidance, mapping each standard to the key concepts it provides, the ocean accounting applications it enables, and the specific circulars where detailed implementation guidance is provided. This mapping demonstrates the integrated use of standards across the accounting system.

Table 3.1: Application of statistical standards in ocean accounts

The integrated use of these standards is demonstrated in the worked example in TG-3.1 Section 3.7, where:

• SEEA EA's IUCN GET classification (M1.1 Seagrass, MFT1.2 Mangroves) defines the ecosystem assets for extent accounts (Table 5)
• SEEA EA's Ecosystem Condition Typology structures the condition variables (Table 6: canopy density B2, leaf litter production B3)
• SEEA EA's ecosystem service typology identifies provisioning (fish nursery) and regulating services (coastal protection, carbon sequestration) for valuation
• SEEA CF provides the asset account structure for fish stocks (Table 7: natural growth, gross catch, depletion)
• SNA 2025 thematic accounting framework supports valuation using net present value of resource rents (4% discount rate applied)
• The monetary ecosystem asset account (Table 8) records degradation (USD 1.76 million) analogous to SNA depletion

This integrated application of standards ensures that the accounts are internally consistent, internationally comparable, and capable of supporting the cross-stack policy applications described in TG-1.1 National Ocean Budgets and TG-2.1 Biophysical Indicators.

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: GOAP Secretariat

Reviewers: GOAP Technical Expert Panel

5. References