Overview of Relevant Statistical Standards

1. Outcome

After reading this circular, you will understand:

• How three international standards fit together to give you the accounting architecture for ocean accounts -- what the SNA 2025 covers (economic activity), what the SEEA Central Framework adds (physical stocks and flows of natural resources), and what SEEA Ecosystem Accounting contributes (ecosystems as spatial units with measurable condition and services).
• Why these standards matter for policy decisions you support. When a government prepares a national ocean budget (TG-1.1 OA and National Budget Processes), it needs 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. When compilers build asset accounts for marine natural resources (TG-3.1 Asset Accounts), they apply SEEA CF guidance on physical depletion and monetary valuation to reveal whether fisheries extraction is sustainable. When analysts measure ecosystem services from coastal ecosystems (TG-2.4 Ecosystem Goods and Services), they use SEEA EA's spatial framework to quantify mangrove carbon sequestration, coral reef coastal protection, and seagrass nursery habitat services -- information that directly shapes marine protected area design and blue carbon finance.
• Which classification systems you will use to organise ocean data consistently -- and why each one exists.
• Where emerging ocean-specific standards stand and how the GOAP Technical Guidance bridges the gap until a formal SEEA Ocean standard is adopted.

Key terms introduced here are defined in TG-0.6 Glossary.

2. Requirements

Essential prerequisites:

• 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

Helpful background:

• TG-0.6 Glossary -- for terminology definitions used throughout this circular

3. Guidance Material

The standards described here form a coherent, layered system. Think of them as nested frameworks, each extending the one before it:

• The System of National Accounts (SNA) tells you how much economic activity your country generates -- including from the ocean.
• The SEEA Central Framework extends the SNA to track physical stocks of natural resources (like fish) and physical flows between the environment and the economy (like tonnes of fish caught).
• SEEA Ecosystem Accounting goes further, treating entire ecosystems -- coral reefs, mangroves, seagrass meadows -- as measurable assets with condition scores and service flows.
• Ocean Accounts apply all three standards to the marine and coastal domain, adding governance and social dimensions.

This section examines each standard in turn, highlighting what it lets you measure and where you will apply it. For guidance on data quality considerations applicable across all ocean accounting work, see TG-0.7 Quality Assurance Principles.

Figure 0.2.1: Statistical standards framework hierarchy^[1]

3.1 System of National Accounts 2025

What question does this answer? How much economic value does your country's ocean generate -- and is that value sustainable?

The System of National Accounts (SNA) is the internationally agreed standard for measuring economic activity. Countries use it to compile GDP and other national accounts statistics. The 2025 edition, adopted by the United Nations Statistical Commission at its 56th session in March 2025, strengthens linkages with environmental accounting and introduces concepts directly relevant to ocean accounts^[2].

At its core, the SNA defines an integrated framework consisting of the sequence of economic accounts (recording flows between institutional sectors), supply and use tables (showing how products move through the economy), and balance sheets (recording stocks of assets and liabilities)^[3]. You build ocean accounts on top of this framework. In the Ocean Accounts Framework (TG-0.1), the SNA's integrated accounts define and structure Edge E3 -- the monetary flows between assets and economic sectors. The 2025 SNA now refers to "thematic and extended accounts" (replacing the earlier "satellite account" terminology from the 2008 SNA) to better reflect how these compilations integrate within the broader national accounting framework^[3:1].

Key concepts for ocean accounting

The SNA 2025 provides several foundational concepts you will use throughout ocean accounting work.

The integrated framework of national accounts -- which means the sequence of economic accounts, supply and use tables, labour market tables, and the table on capital services^[3:2] -- gives you the structure for ocean economy thematic accounts. When you compile ocean economy accounts (TG-3.3 Economic Activity Relevant to the Ocean), you extract ocean economy sub-matrices from these integrated tables, following the same accounting identities and valuation principles that keep the national accounts in balance.

The sequence of economic accounts tracks production of goods and services, the generation and distribution of income, the use of income for consumption or saving, and capital accumulation, culminating in balance sheets of assets and liabilities^[4]. For the ocean economy, this sequence lets you measure gross value added by ocean industries (fishing, aquaculture, maritime transport, offshore energy), income flows 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: it explicitly recognises natural resources as a separate asset category, with renewable energy resources now also explicitly included^[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 covers seabed minerals, offshore energy resources (including renewables like offshore wind and tidal energy), aquatic biological resources such as fish stocks, and coastal land.

The 2025 SNA also introduces the concept of natural capital -- which it defines as "the combination of natural resources and ecosystem assets"^[6]. In practice, this bridges the SNA's treatment of individual natural resources with the ecosystem approach in SEEA Ecosystem Accounting. This matters because ocean accounts 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 shows how to compile fish stock asset accounts (using SEEA CF) and coral reef ecosystem asset accounts (using SEEA EA) using complementary, consistent methodologies that you can aggregate 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 has significant implications for ocean accounting. When fish stocks are harvested beyond sustainable levels, the resulting depletion counts as a cost that reduces net measures of production. The SNA now emphasises that the volume change of net domestic product (NDP) is 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 gives you stronger signals about whether ocean-based economic activities are sustainable.

Concrete application: When you compile structural indicators for the ocean economy (TG-2.5 Structure and Function of the Ocean Economy), you 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 sets clear criteria for what counts as economic production. The key test: an 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 determines how you treat different types of ocean activity. Fish growing in aquaculture facilities counts as production (analogous to livestock rearing), while the natural growth of wild fish stocks in unmanaged international waters does not^[8:1]. The SNA clarifies that even when natural resources like fish under a quota regime become more numerous, this growth "is not under the direct control, responsibility and management of an institutional unit and thus is not treated as production"^[9].

What does this mean for your work? Aquaculture production goes into ocean economy gross value added and contributes to ISIC Division 03 (Fishing and Aquaculture) output reported in TG-3.3. Natural growth of wild fish stocks, by contrast, does not count as production -- instead, you record it as an addition to stock in the physical asset account in TG-3.1 Table 7, where it offsets extraction (catch) and natural mortality to calculate changes in fish stock biomass.

Asset boundary

Natural resources appear on the SNA's balance sheets only when institutional units exercise effective ownership -- that is, when they "are actually in a position to be able to benefit from them"^[10]. For ocean accounting, resources within a country's Exclusive Economic Zone (EEZ) are generally within scope, because the coastal state exercises sovereign rights over them. Resources in the high seas "over which no ownership rights can be exercised" fall outside the asset boundary^[10:1]. The SNA explicitly notes that ecosystem assets sit outside its integrated framework, but recommends compiling ecosystem accounts according to SEEA Ecosystem Accounting^[11].

For resources in areas beyond national jurisdiction (ABNJ), the BBNJ Agreement -- 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, which entered into force on 17 January 2026 -- may provide new frameworks for accounting treatment as its governance structures develop^[12]. The Agreement establishes new institutional arrangements for marine genetic resources, area-based management tools, environmental impact assessments, and capacity-building in ABNJ. Over time, these may clarify how to attribute benefits from high seas resources and thus inform asset accounting boundaries. For guidance on deep-sea and ABNJ accounting, see 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]. It describes the SEEA as providing "a comprehensive set of monetary and non-monetary accounts covering natural resources and ecosystem assets"^[13] and "strongly encourages" compilation of ecosystem accounts according to SEEA Ecosystem Accounting^[11:1]. Importantly for this Technical Guidance, the 2025 SNA 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) gives you the methodological basis for compiling ocean economy accounts as a cross-cutting segment of the national economy. When you prepare the ocean economy thematic supply and use tables described in TG-3.3 Section 3.4, you follow SNA 2025 guidance to identify 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). You extract these from 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

What question does this answer? What does your country take from the ocean, what does it put back, and how much is left?

The SEEA Central Framework (SEEA CF) is a multipurpose framework for describing the interactions between the economy and the environment, and for measuring 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 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]. In practice, you classify these into seven 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 matters most -- it covers 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, stating that it covers "all natural resources, cultivated biological resources and land within a country of reference (including resources within a country's exclusive economic zone)"^[19]. For high seas resources, the scope is narrower: "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 gives you the framework for measuring physical flows between the environment and the economy. All flows from the environment to the economy fall under natural inputs -- which means 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), complementing the monetary supply and use tables of the SNA.

For ocean accounting, the physical flow accounts let you measure: 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 covers residual flows -- emissions and waste returned to the environment -- which are critical for understanding pollution pressures on marine ecosystems.

Concrete application: When you compile physical flow accounts for a coastal region (TG-3.2 Flows from Environment to Economy), you 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 gives you the foundation for 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 you then value 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 defines 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]. In plain terms: if you take out more than nature puts back, the difference is depletion.

The SEEA CF also addresses discards: "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 matters directly for fisheries accounting, where discards can represent a significant portion of total catch. Detailed methodological guidance for asset accounts is in TG-3.1 Asset Accounts.

Aquaculture versus wild capture

The SEEA CF maintains a clear distinction between cultivated and natural biological resources. Cultivated biological resources -- including aquaculture -- fall within the production boundary, meaning you treat aquaculture production similarly to agricultural production^[25]. Natural biological resources (including wild fish) enter the economy at the point of harvest^[26]. This distinction determines how you record changes in fish stocks: changes in aquaculture stocks count 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 in TG-3.1 Table 1a, cultivated aquatic resources (aquaculture) and natural aquatic resources (wild fish) appear 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 (3,000 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 covers individual environmental assets comprehensively, it does not treat the ocean itself as an environmental asset. The framework notes that it "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]. Marine ecosystems as integrated spatial units also fall outside SEEA CF's scope -- for that, you need SEEA Ecosystem Accounting. The SEEA CF does not specifically address coral reefs, mangroves, seagrass meadows, or other marine ecosystem types; those are covered in the next section.

3.3 SEEA Ecosystem Accounting

What question does this answer? How healthy are your marine ecosystems, what services do they provide, and what are they worth?

SEEA Ecosystem Accounting (SEEA EA) was adopted by the United Nations Statistical Commission in March 2021 as an international statistical standard for ecosystem accounting^[27]. Where the SEEA CF tracks individual resources (fish, minerals, water), SEEA EA treats ecosystems as integrated spatial units -- ecosystem assets -- that you measure 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 Convention on Biological Diversity definition. An ecosystem asset is the statistical unit you actually measure: "contiguous spaces of a specific ecosystem type characterized by a distinct set of biotic and abiotic components and their interactions"^[29]. You assign each ecosystem asset to an ecosystem type -- a category that "reflects a distinct set of abiotic and biotic components and their interactions"^[30].

Ecosystem services are "the contributions of ecosystems to the benefits that are used in economic and other human activity"^[31]. They represent flows generated by ecosystems that feed into the production of benefits -- and they are distinct from the benefits themselves. In the Ocean Accounts Framework (TG-0.1), final ecosystem services correspond to Edge E9 (flows from environmental stocks to the economy) and Edge E10 (flows to society), while intermediate services correspond to Edge E11 (flows within the environmental domain). The SEEA EA distinguishes final ecosystem services (directly used by economic units or households) from 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]. Together, they give you a complete picture -- from physical area, through health, to monetary value:

1. Ecosystem extent accounts -- record the areas of different ecosystem types and track changes over time. This tells you whether you are gaining or losing mangroves, seagrass, or reef area.
2. Ecosystem condition accounts -- record the quality of ecosystem assets through condition variables and indicators. This tells you whether your remaining ecosystems are healthy or degrading.
3. Ecosystem services flow accounts in physical terms -- record the supply and use of ecosystem services in physical units. This tells you how much coastal protection, carbon sequestration, or fish nursery service your ecosystems provide.
4. Ecosystem services flow accounts in monetary terms -- record the value of ecosystem services in currency units. This tells you the economic contribution of ecosystem services.
5. Monetary ecosystem asset accounts -- record the value of ecosystem assets as natural capital. This tells you the total capital value of your marine ecosystems.

An important distinction: the Statistical Commission adopted the physical ecosystem accounts (chapters 3 through 7) as a full international statistical standard, but adopted the valuation chapters (8 through 11) at the level of "internationally recognized statistical principles and recommendations"^[34]. This means the valuation methodologies carry a different level of international endorsement than the physical accounting frameworks -- something to note when your ocean accounting work involves monetary valuation of marine ecosystem services and assets^[27:1].

Concrete application: When you compile ecosystem accounts for a coastal zone, you 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), natural expansion (+0.3 km2), and storm damage (-2.0 km2), yielding closing extent of 496.8 km2 mangroves. For seagrass, storm damage (-0.8 km2) yields closing extent of 199.2 km2. 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 148.7 million after accounting for degradation (-USD 1.65 million), conversions (-USD 1.32 million), and a downward revaluation reflecting revised long-term coastal development projections (-USD 5.08 million), partially offset by revaluation from updated coastal protection valuations (+USD 8.25 million) and the value of natural expansion and restoration (+USD 0.5 million). The net revaluation effect and physical changes together produce the closing value.

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 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

Why do we use this classification? Because it groups marine habitats by ecological function and sensitivity to human activity -- exactly the distinctions that matter for ecosystem accounting.

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 for ecosystems that depend on fluxes between contrasting environments^[39]. For ocean accounting, the relevant realms are:

• Marine realm (M) -- covering marine shelves (M1), pelagic ocean waters (M2), deep-sea floors (M3), and anthropogenic marine systems (M4)
• Transitional realms -- covering 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 your marine ecosystem extent accounts.

Concrete application: When you apply the IUCN GET to coral reef ecosystem accounts (TG-6.1 Coral Reef Ecosystem Accounting), you classify photic coral reefs as ecosystem functional group M1.3 within the Marine Shelf biome (M1). This classification lets you 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 -- you 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

You measure ecosystem condition using a three-stage approach: presenting condition variables, deriving condition indicators, and optionally deriving composite indices^[41]. The SEEA EA links condition to the concept of ecosystem integrity -- which means "the ecosystem's capacity to maintain its characteristic composition, structure, functioning and self-organization over time within a natural range of variability"^[42]. For ecologists, this will be a familiar concept; for statisticians, think of it as the reference state against which you measure deviation. Key drivers of condition for marine ecosystems include bathymetric profile, climate factors (including ocean acidification and temperature), substrate type, ocean circulation, salinity, and human activities^[43].

3.4 SEEA-Oceans (Emerging)

Where does ocean-specific accounting guidance stand today?

There is not yet a separate "SEEA-Oceans" standard adopted by the United Nations Statistical Commission. Instead, the SEEA EA 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].

This 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 the Statistical Commission adopts.

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 let you measure^[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 in action. 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. Ocean data "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

Why do classification systems matter? Because consistent classification ensures your data can be compared across countries and over time. Without agreed codes for industries, products, government spending, and ecosystem types, every country's ocean accounts would be a one-off exercise with no basis for international benchmarking.

The key classifications for ocean accounting span economic activities, products, government expenditure, environmental protection activities, and ecosystem types.

International Standard Industrial Classification (ISIC)

What does ISIC tell you? Which industries make up your ocean economy, and how do they compare with other countries' ocean economies.

The International Standard Industrial Classification of All Economic Activities (ISIC) classifies economic activities into a four-level hierarchy: sections (alphabetic), divisions (2-digit), groups (3-digit), and classes (4-digit)^[51]. ISIC Revision 5 was endorsed by the UN Statistical Commission at its 55th session in March 2024^[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) -- covering 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]. Note that processing of fish at land-based plants falls separately in Division 10 (Food products)^[57]. As ISIC Rev.5 was endorsed in March 2024 and its final text is now published, compilers should consult the definitive classification structure when assigning codes.

Concrete application: When you compile the ocean economy sector composition indicators in TG-2.5 Table 3.1, you classify ocean industries using ISIC codes. Marine fishing (ISIC 0311) and marine aquaculture (ISIC 0321) fall 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) fall 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)

What does CPC tell you? What ocean products and services flow through your economy -- and in what quantities.

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

Division 04 (Fish and Other Fishing Products) provides detailed categories for live fish, fresh fish, crustaceans, molluscs, and other aquatic products, distinguishing 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]. As CPC Ver.3.0 was endorsed in March 2024 and its final text is now published, compilers should consult the definitive classification structure when assigning codes.

Classification of Functions of Government (COFOG)

What does COFOG tell you? How much your government spends on ocean-related functions -- fisheries management, maritime infrastructure, marine environmental protection.

The Classification of Functions of Government (COFOG) classifies 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

What do these tell you? How much is spent specifically on protecting marine environments and managing marine resources.

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

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 described 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 you use them 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. 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]. You may need supplementary classification detail for comprehensive ocean accounts.

3.6 Standards Application Summary

Table 3.1 maps each standard to the concepts it provides, the ocean accounting applications it enables, and the circulars where you find detailed implementation guidance. Use this as a reference for locating the right standard for your accounting task.

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 1.65 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 Aggregate Biophysical Indicators of Environmental State.

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