Aquaculture Accounts

The guidance covers production boundary treatment, asset classification for aquaculture stocks, carrying capacity and sustainable production considerations, and environmental interactions including feed inputs and waste outputs. This Circular provides the accounting foundation for the thematic methodologies in TG-6.8 Aquaculture Thematic Methods.

This Circular requires familiarity with:

• TG-0.1 General Introduction to Ocean Accounts: conceptual framework and key components of Ocean Accounts
• TG-0.2 Overview of Relevant Statistical Standards: methodological foundations in SNA 2025, SEEA CF, and SEEA EA
• TG-3.1 Asset Accounts: general methodology of physical and monetary asset accounts
• TG-3.3 Economic Activity Relevant to the Ocean: industry classification framework for aquaculture

Related Circulars:

Aquaculture has grown rapidly worldwide, with production exceeding wild-capture fisheries for human consumption in recent years. This expansion creates accounting challenges that differ from those of traditional fisheries. Whilst wild-capture fisheries extract natural biological resources from common-pool stocks, aquaculture involves deliberate cultivation under the direct control, responsibility and management of institutional units. This placement of aquaculture within the production boundary of the national accounts carries substantial implications for how aquaculture stocks and their changes are recorded.

This section examines the production boundary treatment (Section 3.1), compilation procedures for aquaculture accounts (Section 3.2), asset classification for aquaculture stocks (Section 3.3), carrying capacity considerations for sustainable production (Section 3.4), and environmental interactions (Section 3.5). Section 3.6 presents worked examples demonstrating account compilation with synthetic data. The guidance presented here aligns with the SEEA Central Framework, the SEEA Agriculture, Forestry and Fisheries (SEEA AFF), and the 2025 SNA treatment of cultivated biological resources.

3.1 Production Boundary Treatment

The distinction between aquaculture and wild-capture fisheries governs their accounting treatment. The distinction rests on the production boundary—the demarcation between economic activity treated as production and natural processes that fall outside the production boundary. For guidance on the relationship between natural and produced assets, see TG-3.1 Asset Accounts Section 3.4.1 (Aquatic resources) and Section 3.6 (Produced Assets in the Ocean Domain).

The production boundary and aquaculture

The SEEA Central Framework establishes that “the production boundary includes all activities carried out under the responsibility, control and management of a resident institutional unit in which labour and assets are used to transform inputs of goods and services into outputs of other goods and services”. Applying this principle to aquatic resources, the SEEA CF states that “the growth of fish in fish farms and other aquaculture facilities is treated as a process of production”.

The FAO definition of aquaculture, adopted in the SEEA CF, provides the operational basis for this distinction:

“Aquaculture is the farming of aquatic organisms, including fish, molluscs, crustaceans and aquatic plants. Farming implies some form of intervention in the rearing process to enhance production, such as regular stocking, feeding, protection from predators, etc. Farming also implies individual or corporate ownership of the stock being cultivated. For statistical purposes, aquatic organisms that are harvested by an individual or corporate body that has owned them throughout their rearing period contribute to aquaculture, while aquatic organisms that are exploitable by the public as a common property resource, with or without appropriate licences, are the harvest of fisheries.”

Table 3.9.1: Aquaculture production boundary decision criteria

This decision table summarises the distinguishing characteristics that determine whether aquatic resources fall on the natural or cultivated side of the production boundary. In practice, some operations exhibit characteristics from both columns, requiring case-by-case assessment against the three criteria established above.

Implications for accounting treatment

The placement of aquaculture within the production boundary has several implications:

Output measurement. The growth of aquaculture organisms constitutes output in the national accounts sense. This growth is recorded as production of the aquaculture industry, contributing to GDP and value added. In contrast, the natural growth of wild fish stocks is not treated as production and does not contribute directly to economic output—only the extraction (harvest) enters the economic accounts. For guidance on how natural resource extraction is treated, see TG-3.2 Flows from Environment to Economy. The industry classification of aquaculture within the ocean economy is addressed in TG-3.3 Economic Activity Relevant to the Ocean.

Asset classification. Aquaculture stocks are classified as produced assets rather than natural resources. This contrasts with wild fish stocks, which are classified as natural (non-produced) assets subject to depletion accounting. The distinction between produced and non-produced assets affects balance sheet treatment and the calculation of depletion-adjusted income measures. The framework for natural aquatic resource accounting is presented in TG-3.1 Asset Accounts Section 3.4.1.

Capital formation. Investment in aquaculture stocks is recorded as gross fixed capital formation (for breeding stocks) or changes in inventories (for stocks being raised for harvest). This treatment parallels the accounting for livestock in agriculture, where breeding cattle are treated as fixed assets and animals raised for slaughter are treated as inventories.

For mixed and transitional cases (ranching, stock enhancement, IMTA), see the reclassification guidance in Section 3.3.

This section provides a step-by-step procedure for compiling aquaculture accounts, integrating production accounts, asset accounts, and environmental flow accounts. The procedure assumes that countries have established coordination mechanisms between statistical offices, aquaculture regulatory agencies, and environmental authorities as described in TG-4.7 National Data Coordination Architectures.

Step 1: Delineate aquaculture operations and classify systems

Identify all aquaculture operations within the national accounting boundary and classify them according to:

a) System type—open systems (cage culture, net-pens, on-bottom culture), closed systems (tanks, raceways, recirculating aquaculture systems), or semi-intensive systems (pond culture, integrated systems);

b) Species or species groups—finfish (salmon, sea bass, tuna), crustaceans (shrimp, prawns), molluscs (oysters, mussels), aquatic plants (seaweed);

c) Salinity—marine aquaculture (operating in coastal waters or offshore), brackish water aquaculture, or freshwater aquaculture (the latter is outside the ocean accounting boundary but may be included in national aquaculture accounts; see the note on freshwater aquaculture scope at the end of this step);

d) Purpose—food production, ornamental species, stock enhancement/ranching (see Section 3.1 for treatment of transitional cases).

Data sources include aquaculture licensing registries, fisheries statistical databases (FAO FishStatJ; see TG-4.10 Extending Fisheries Statistics Section 3.8.1 for full database description, including coverage, refresh frequency, and limitations), remote sensing analysis for spatial extent of cage culture operations (TG-4.1 Remote Sensing and Geospatial Data), and industry census data from statistical offices.

Freshwater aquaculture scope note: Freshwater aquaculture (catfish, tilapia, carp, and other freshwater species) falls outside the ocean accounting boundary but is within scope for SNA national production accounts and should be compiled using the same methodology described in this Circular. Within ocean accounts, freshwater aquaculture production should appear as a memorandum item or in a supplementary “All Aquaculture” table that includes freshwater alongside marine and brackish production, with clear delineation by salinity category. The national total should be reconcilable to FAO FishStatJ national aquaculture production figures, which include all systems, to support cross-country comparability and external validation.

Step 2: Compile production accounts

Assemble aquaculture production data following the Supply and Use Table (SUT) framework described in TG-3.3 Economic Activity Relevant to the Ocean:

a) Output—Record aquaculture production in physical terms (tonnes live weight) and monetary terms (value at basic prices). Output includes both harvest for sale and intermediate transfers between hatcheries and grow-out operations.

b) Intermediate consumption—Record feed inputs (fishmeal, fish oil, plant-based feeds), fingerlings/juveniles purchased from hatcheries, veterinary services, energy inputs, and other operational inputs. Feed inputs from wild fisheries should be separately identified to enable calculation of fish-in-fish-out ratios (Section 3.5).

c) Value added—Calculate gross value added as output minus intermediate consumption. This measures the aquaculture sector’s contribution to GDP.

a) Opening stock—Determine stock biomass at the beginning of the accounting period using the following tiered data source hierarchy: (1) facility biomass records as the primary source; (2) regulatory production returns where facility records are absent or unreliable; (3) statistical survey estimates where regulatory returns are unavailable; (4) model-based estimates using licensed area multiplied by species-specific average stocking density norms sourced from national fisheries authority technical tables, as a last resort. Compilers must flag fallback methods (sources 3 and 4) in metadata following TG-0.7 Quality Assurance conventions. For breeding stocks, record number of broodstock by species. For growing stocks, record total biomass by species and cohort/size class where data permit.

b) Additions to stock—Record natural growth (biomass increase from feeding and maturation), hatchery production or purchases of juveniles (additions to growing stocks), and reclassifications from natural resources (wild-caught organisms introduced for fattening or broodstock).

c) Reductions in stock—Record harvest (sales or transfers to processing), normal losses (routine mortality from disease, predation, environmental stress), catastrophic losses (disease outbreaks, harmful algal blooms, storm damage), escapes (reclassifications to natural resources), and culling (removal of unproductive broodstock).

d) Closing stock—Verify that closing stock equals opening stock plus additions minus reductions. Reconcile discrepancies through data quality audits.

c) Revaluations—Record holding gains or losses reflecting price changes during the accounting period, separate from volume changes.

For valuation methodology, see TG-3.1 Asset Accounts Sections 3.3 (monetary asset accounts) and 3.6 (produced assets).

Step 5: Compile environmental flow accounts

Record flows between aquaculture operations and the environment following the methodology in TG-3.2 Flows from Environment to Economy and TG-3.4 Flows from Economy to Environment:

b) Residual outputs—Record nutrient emissions (nitrogen and phosphorus from uneaten feed, faeces, excretion—measured in tonnes N and P), chemical releases (therapeutants, antifoulants—kilograms active ingredient), organic waste deposition (tonnes organic matter), and escapes (number or biomass, classified by species).

c) Spatial attribution—Assign emissions and environmental pressures to receiving ecosystems or management zones to enable integration with ecosystem condition accounts (TG-3.1 Asset Accounts Section 3.5.2).

Data sources include environmental monitoring programs, aquaculture environmental impact assessments, nutrient budget models for cage culture operations, veterinary chemical use records, and escape event reporting systems. See TG-2.7 Pollution Flows for emission accounting methodology.

Step 6: Assess carrying capacity and sustainability indicators

Integrate aquaculture accounts with ecosystem accounts to assess sustainability:

a) Stocking density analysis—Compare actual stocking levels against recommended carrying capacity thresholds for different system types and species. Excessive stocking reduces growth rates, increases disease risk, and elevates environmental pressures.

b) Feed conversion efficiency—Calculate feed conversion ratios (FCR—mass of feed per mass of production) and fish-in-fish-out ratios (FIFO—mass of wild fish in feed per mass of farmed output) as indicators of resource efficiency. See TG-2.11 Resource Efficiency for indicator methodology.

c) Environmental pressure indicators—Calculate nutrient loading per unit area of coastal zone, sediment organic enrichment indices beneath cage sites, and chemical loading. Compare against water quality standards or ecosystem health thresholds from TG-2.1 Biophysical Indicators.

d) Habitat conversion tracking—Where aquaculture expansion involves coastal habitat conversion (mangrove clearance for pond construction, seagrass loss beneath cage moorings), record extent changes in ecosystem accounts for affected habitats. See TG-6.2 Mangrove and Coastal Wetland Accounting for mangrove accounting methodology.

Step 7: Integration and consistency checks

Ensure internal consistency and integration across account types:

a) Production-asset consistency—Verify that harvest recorded in production accounts equals reductions from harvest in asset accounts. Reconcile discrepancies through improved measurement or identification of unrecorded flows.

b) Feed flow consistency—Ensure that wild fish used for feed recorded in aquaculture intermediate consumption matches extractions recorded in fisheries accounts (TG-1.5 OA and Fisheries Management).

c) Ecosystem integration—Link aquaculture environmental pressures (nutrient loading, habitat conversion) to changes in ecosystem condition indicators for receiving ecosystems. Declining condition in coastal ecosystems may signal that aquaculture intensity exceeds ecological carrying capacity.

d) Temporal consistency—Maintain consistent time series by adjusting for changes in system boundaries, classification, or measurement methodology. Document adjustments in metadata following TG-0.7 Quality Assurance standards.

This compilation procedure provides the foundation for policy-relevant analysis. It allows governments to assess whether aquaculture expansion is sustainable, identify environmental pressure points requiring management intervention, and track progress towards blue economy and biodiversity targets.

The classification of aquaculture assets must distinguish between different types of aquaculture systems and different categories of aquaculture stocks within those systems. This section builds on the general asset classification framework in TG-3.1 Asset Accounts Section 3.2 (Step 2).

Classification of aquaculture stocks

Within aquaculture operations, stocks must be classified according to their function in the production process:

Breeding stocks (fixed assets). Aquatic organisms maintained for reproduction purposes are treated as fixed assets in the SNA classification. These resources yield repeat products (eggs, juveniles, milt) over multiple production cycles. In asset accounts, they are recorded separately from stocks held for sale, and their growth is recorded as gross fixed capital formation. The 2025 SNA confirms that “animal resources yielding repeat products” include “aquatic resources maintained for controlled reproduction”.

Physical asset account structure

Table 3.9.2 presents the structure of a physical asset account for cultivated aquatic resources, following the format in SEEA CF Table 5.22.

Table 3.9.2: Structure of physical asset account for cultivated aquatic resources

Note on monetary account columns: Where monetary columns are added to Table 3.9.2, revaluation entries (holding gains/losses from price changes) must be presented as a separate line item distinct from the volume change entries above, to avoid confounding volume and price effects in the time series. See Step 4 for the method hierarchy governing monetary valuation.

Note on breeding stock depreciation illustration: For a cohort replaced after two spawning cycles (typically two years for Atlantic salmon), a compiler would record in Year 1: GFCF for the new cohort acquisition; in Year 2: CFC (consumption of fixed capital) through the year as productive capacity declines, and at end of Year 2: the remaining book value written down simultaneously with new cohort GFCF. Both entries appear in the same accounting period when mass replacement occurs.

This structure parallels the asset account for natural aquatic resources presented in TG-3.1 Asset Accounts Table 1, enabling side-by-side comparison and consolidation of total aquatic resource accounts.

Growth in stock encompasses both increase in numbers (through hatching, natural reproduction where relevant) and increase in biomass (growth of individual organisms). For breeding stocks, only the growth of the breeding population is recorded. The juveniles produced are recorded as additions to growing stocks.

Reclassifications record transfers between natural and cultivated categories. Introduction of wild-caught organisms as broodstock or seed represents a reclassification from natural to cultivated resources. Release of cultured organisms for ranching or enhancement programmes, and escapes from aquaculture facilities, represent reclassifications from cultivated to natural resources.

Harvest records the removal of organisms from growing stocks for sale or processing. For breeding stocks, animals removed for slaughter (culling of unproductive or excess broodstock) are recorded as reductions.

Normal losses include mortality from routine causes such as disease, predation, and environmental stress within normal operating parameters.

Catastrophic losses record exceptional losses from disease outbreaks, harmful algal blooms, extreme weather events, or other unexpected events beyond normal operating expectations.

Aquaculture stocks are valued following standard SNA principles for produced assets. For inventory valuation, the 2025 SNA treatment of work-in-progress recognises that cost accumulation methods may not provide satisfactory results where growth is non-linear. Similar challenges arise for aquaculture, where growth is not linear and substantial mortality may occur. For guidance on valuation approaches, see TG-1.9 Valuation.

For breeding stocks (fixed assets), valuation should reflect the expected future economic benefits from the breeding capacity. Depreciation is recorded for the decline in value as breeding animals age and their productive capacity declines.

3.4 Carrying Capacity Considerations

The concept of carrying capacity in aquaculture contexts refers to the maximum production that can be sustained in a given environment without causing unacceptable environmental impacts or production failures. The FAO definition of aquaculture (see footnote ) describes aquaculture as involving “some form of intervention in the rearing process to enhance production,” whilst ISIC Rev.4 Group 032 describes aquaculture as involving “some form of intervention in the rearing process… Farming also implies individual or corporate ownership of the stock being cultivated”.

The Statistical Framework for Measuring the Sustainability of Tourism (SF-MST) provides a parallel treatment of carrying capacity in its discussion of tourism environmental limits (para 4.103), supporting the broader applicability of carrying capacity concepts within environmental-economic accounting. The SEEA AFF notes that asset accounts “can be used to better understand the carrying capacity of agricultural areas with respect to livestock, for example, the number of cattle per hectare”. This is a direct statistical precedent for applying carrying capacity analysis to cultivated biological resources.

Authoritative sources for carrying capacity thresholds

For accounting purposes, carrying capacity considerations affect the interpretation of production levels and the assessment of sustainability:

Stock assessment. The opening and closing stocks of cultivated aquatic resources should be assessed against the carrying capacity of the facilities and environment. Stocking at levels that exceed carrying capacity may lead to reduced growth rates, increased mortality, disease outbreaks, and environmental degradation.

Sustainable yield. Whilst the concept of maximum sustainable yield (MSY) is traditionally applied to wild fisheries (see TG-6.7 Fisheries Stock Assessment), analogous concepts apply to aquaculture in open systems. Production that exceeds ecological carrying capacity may degrade the supporting ecosystem, reducing its capacity to support future production.

Environmental condition. For open aquaculture systems operating within marine ecosystems, the ecosystem condition accounts described in TG-3.1 Asset Accounts Section 3.5.2 should capture changes in environmental quality that affect or are affected by aquaculture operations.

Integration with ecosystem accounts

The SEEA Ecosystem Accounting framework provides a basis for linking aquaculture accounts with ecosystem condition and service accounts. Key linkages include:

Supporting services. Marine ecosystems provide water quality maintenance, waste assimilation, and habitat functions that support aquaculture production. Degradation of these supporting services may reduce carrying capacity and production potential.

Provisioning services. In some extensive aquaculture systems, natural productivity contributes directly to fish growth, representing a flow of ecosystem services to the aquaculture activity.

Regulating services. Ecosystems regulate water temperature, disease prevalence, and harmful algal blooms, all of which affect aquaculture production.

For guidance on ecosystem service accounting, see TG-3.2 Flows from Environment to Economy and TG-2.4 Ecosystem Goods and Services.

Aquaculture, particularly in open marine systems, interacts substantially with the surrounding environment. These interactions must be captured in ocean accounts to record the aquaculture sector’s environmental dependencies and impacts in full. This section complements the general guidance on environmental flows in TG-3.2 Flows from Environment to Economy and TG-3.4 Flows from Economy to Environment.

Inputs from the environment

Aquaculture operations draw upon environmental inputs that should be recorded in physical supply and use accounts:

Water abstraction. Land-based aquaculture systems (tanks, ponds, raceways) may abstract large volumes of freshwater or seawater. These abstractions should be recorded in water accounts following the methodology in SEEA-Water. For marine cage culture, passive water exchange through nets or tidal action is not abstraction and should not be recorded. Only pumped intake into a controlled facility qualifies (see the decision rule in Step 5a). Water quality requirements for cage culture operations should be noted as context for ecosystem condition assessment.

Feed from wild fisheries. A material environmental interaction is the use of fish meal and fish oil derived from wild-caught fish as feed inputs for carnivorous aquaculture species. The SEEA AFF notes that “fish products provide nutrition in a stable and concentrated form, which enables the fish to feed efficiently and grow to their full potential. Many of the intensively farmed fish are carnivorous, including, among others, Atlantic salmon, trout, sea bass and turbot. In line with the emergence of modern aquaculture in the 1970s, fish meal and fish oil have become major components of feed for those species”.

For resource efficiency analysis, see TG-2.11 Resource Efficiency.

Ecosystem services. As noted in Section 3.4, aquaculture benefits from ecosystem services including water quality maintenance, disease regulation, and larval supply (for some species). These services represent flows from the environment to the economy that may be captured in ecosystem service accounts.

Outputs to the environment

Aquaculture operations generate outputs to the environment that should be recorded in residual flow accounts:

Nutrient loading. Aquaculture releases nutrients (primarily nitrogen and phosphorus) through uneaten feed, faeces, and metabolic excretion. In open systems, these nutrients are released directly to the marine environment and may contribute to eutrophication in poorly flushed areas. Nutrient releases should be recorded in emission accounts following the SEEA CF methodology for residual flows. For guidance on pollution flow accounting, see TG-2.7 Pollution Flows.

Organic matter. Feed waste and faeces settling beneath cage sites can alter benthic conditions, affecting sediment chemistry and benthic communities.

Chemical releases. Aquaculture may involve use of therapeutants (antibiotics, parasiticides), antifoulants, and other chemicals that are released to the environment. These should be recorded following standard emission accounting principles. Chemical treatments for parasites (e.g., hydrogen peroxide, azamethiphos) are quantifiable where veterinary chemical use records are maintained and should appear in the chemical releases row with a species/compound breakdown where data permit.

Escapes. Organisms that escape from aquaculture facilities represent a flow from the economy to the environment. As noted in Sections 3.1 and 3.3 (Table 3.9.2), these should be recorded as reclassifications from cultivated to natural aquatic resources “in cases where the fish are able to integrate into natural fish stocks”. Where integration is not possible (e.g., non-native species in unsuitable environments), escapes should be recorded as losses.

For detailed methodological guidance on site-specific assessment and integration with ecosystem accounts, see TG-6.8 Aquaculture Thematic Methods. The broader relationship between aquaculture and fisheries within ocean accounting is addressed in TG-1.5 OA and Fisheries Management, which discusses how aquaculture and wild-capture fisheries interact in contributing to ocean-based food production and how both are treated within integrated fisheries governance frameworks.

This section presents three worked examples with synthetic data demonstrating the compilation of aquaculture accounts for common scenarios: a shrimp farm production account, a coastal zone mangrove conversion tracking system, and a salmon cage culture nutrient loading assessment.

Example 1: Coastal shrimp farm production and asset accounts

Table 3.9.4: Shrimp aquaculture physical asset account, 2025

Note on PL stocking unit: Post-larvae (PL) are commercially traded in millions of individuals. The 1,200 tonnes figure represents nursery-stage juveniles at approximately 0.3 g average body weight (approximately 4,000 million individuals or 4.0 billion PL). Where the primary data source is in units of millions of individuals, compilers should convert to biomass using the average individual weight at stocking, which should be documented in facility records or species-specific industry norms. The memo column above illustrates this parallel recording.

Verification: Closing stock (1,000) = Opening stock (800) + Additions (4,700) - Reductions (4,500). Account balances correctly.

Feed conversion and efficiency indicators:

• Feed conversion ratio (FCR) = Feed input / Biomass growth = 6,000 / 3,500 = 1.71 (industry benchmark for intensive shrimp: 1.5-2.0)
• Fish-in-fish-out ratio (FIFO) = Wild fish equivalent of fishmeal / Harvest = (1,500 / 0.225) / 3,800 = 6,667 / 3,800 = 1.75, at the standard fishmeal yield of 22.5 per cent of raw fish (net consumer of wild fish, as FIFO > 1.0)

Environmental flow implications: The 1,500 tonnes of fishmeal embodied in purchased feed, about 6,700 tonnes of wild fish equivalent, represents a wild fish equivalent analytical indicator (FIFO). This should be presented as a satellite table or memo item rather than as a direct natural input in the main accounts, consistent with the double-counting avoidance rule described in Section 3.5 and SEEA AFF para 3.169.

Example 2: Mangrove conversion tracking for shrimp pond expansion

Context: The same coastal nation experienced shrimp aquaculture expansion from 2020-2025, involving conversion of mangrove ecosystems to pond culture. The example demonstrates integration of aquaculture asset accounts with ecosystem extent accounts.

Scenario parameters (synthetic data):

• Mangrove extent 2020: 12,000 hectares
• Mangrove extent 2025: 11,500 hectares
• Shrimp pond extent 2020: 300 hectares
• Shrimp pond extent 2025: 500 hectares
• Documented mangrove-to-pond conversion 2020-2025: 200 hectares
• Other mangrove losses (erosion, development): 300 hectares

Table 3.9.5: Ecosystem extent account for mangrove and shrimp pond ecosystems, 2020-2025

Cross-account consistency: The 200 hectares of mangrove-to-pond conversion appears as a reduction in the mangrove extent account and as an addition to the shrimp pond (produced asset) area. This reclassification tracks the transformation of natural ecosystem assets into cultivated aquaculture infrastructure.

Policy implications: The 4.2% loss of mangrove extent over five years signals environmental pressure from aquaculture expansion. Mangrove ecosystem service losses include carbon sequestration capacity (estimated 3-5 tonnes CO2e/ha/yr), coastal protection value, and nursery habitat for wild fisheries. See TG-6.2 Mangrove and Coastal Wetland Accounting for mangrove accounting methodology, including valuation of ecosystem services lost through conversion.

GBF Target 10 relevance: Countries reporting under the Kunming-Montreal Global Biodiversity Framework must track area under sustainable aquaculture. The 200-hectare mangrove conversion would need to be balanced by demonstrating that the resulting shrimp farms meet environmental sustainability criteria to avoid negative reporting against biodiversity targets.

• Salmon production: 150,000 tonnes live weight harvest
• Feed input: 195,000 tonnes (FCR = 1.3)
• Feed composition: 30% protein, 20% fat, nitrogen content 4.8% of feed, phosphorus content 0.9%
• Estimated nutrient releases applying illustrative release fractions (see note below):
  • Nitrogen: 195,000 tonnes feed × 0.048 × 0.65 (illustrative N release fraction) = 6,084 tonnes N
  • Phosphorus: 195,000 tonnes feed × 0.009 × 0.70 (illustrative P release fraction) = 1,229 tonnes P
• Receiving coastal ecosystems: 15 fjord systems, total surface area 450 km²

Note on release fractions: The nitrogen (0.65) and phosphorus (0.70) release fractions used in this example are illustrative scenario parameters, not authoritative emission factors. They fall within the upper range of published values for intensive fed-finfish systems. Compilers should use release fractions from their national regulatory framework, environmental monitoring programmes, or established reference sources (e.g., HELCOM PLC-Water Guidelines, which specify aquaculture nutrient thresholds for the Baltic Sea, or FAO reference values). Published release fractions vary by feed composition, species, and production system type. Table 3.9.6 illustrates this range:

Table 3.9.6: Published range of nutrient release fractions by aquaculture system type (illustrative)

Table 3.9.7: Nutrient emission account for salmon aquaculture, 2025

Nutrient loading intensity:

• Nitrogen loading = 6,084 tonnes / 450 km² = 13.5 tonnes N/km²/yr
• Phosphorus loading = 1,229 tonnes / 450 km² = 2.7 tonnes P/km²/yr

Ecosystem condition linkages: These nutrient loading rates should be assessed against water quality standards and ecosystem condition indicators from TG-2.1 Biophysical Indicators. Indicators might include:

• Dissolved oxygen levels in bottom waters (hypoxia threshold: < 2 mg/L)
• Chlorophyll-a concentrations (eutrophication indicator)
• Benthic community condition indices beneath cage sites

Carrying capacity assessment: If condition indicators show declining trends (increasing hypoxia, benthic degradation), this signals that aquaculture intensity may exceed the ecological carrying capacity of the receiving fjord systems. Authorities may need to adjust licensing to reduce stocking density or redistribute farms to less-impacted areas.

Data sources: Nutrient release estimates are typically derived from mass-balance models combining feed input data (from industry records), feed composition (from nutritional analysis), and empirically-determined release fractions (from scientific literature or site-specific monitoring). For emission accounting methodology, see TG-2.7 Pollution Flows and TG-3.4 Flows from Economy to Environment.

Cross-stack connections: These worked examples demonstrate integration across the accounting stack:

• Upward to TG-1.x policy: Mangrove conversion and nutrient loading evidence informs decisions on aquaculture zoning, licensing thresholds, and environmental performance standards (TG-1.2 OA and Marine Spatial Planning, TG-1.5 OA and Fisheries Management).
• Lateral to TG-2.x indicators: FCR and FIFO ratios feed into resource efficiency indicators (TG-2.11), and nutrient loading drives water quality indicators (TG-2.1).
• Downward to TG-4.x data: Extent mapping requires remote sensing and geospatial analysis (TG-4.1). Nutrient budget models require data integration from production statistics, feed composition databases, and field monitoring (TG-4.6 Data Harmonisation and Interoperability).

3.7 Provisioning-Service Quantification: Linking Aquaculture Output to Ecosystem Service Accounts

Aquaculture production accounts (Sections 3.2—3.3) measure cultivated output as a produced asset within the SNA production boundary. They do not, by themselves, quantify the provisioning ecosystem services that supporting marine and coastal ecosystems contribute to that output, nor do they quantify the wild-capture and gleaning flows that often coexist with aquaculture in the same coastal zone. Practitioners may consider compiling complementary provisioning-service accounts following SEEA EA Chapter 6, particularly where aquaculture sits alongside wild-capture fisheries, gleaning, or mangrove fuel-wood collection in an integrated coastal accounting area.

The candidate workflows below are presented as parallel quantification pipelines: aquaculture production accounting (covered in Sections 3.2—3.3), wild-capture catch accounting, gleaning, and wood/non-timber forest product (NTFP) provisioning. Each pipeline produces a physical supply table and, where feasible, a monetary supply table. Practitioners may select the workflows applicable to their accounting area and tier their implementation according to data availability.

3.7.1 Aquaculture production accounting (reference)

The physical asset and production accounts compiled per Sections 3.2—3.3 directly populate the provisioning-service entry for cultivated aquatic resources. Output recorded in tonnes live weight by species and system type may be cross-tabulated against the supporting ecosystem (coastal waters, brackish ponds converted from mangrove, offshore cage sites) to indicate the spatial distribution of cultivated provisioning supply. Monetary valuation follows the produced-asset method hierarchy in Step 4 (market price; cost-accumulation fallback). FAO aquaculture statistics, reported through FAO FishStatJ, provide the national benchmark against which compiled accounts may be reconciled.

3.7.2 Wild-capture catch accounting (parallel workflow)

a) Physical measurement. Compile total annual landed catch (kg/yr) from national or regional fisheries agency records, supplemented where coverage is thin by structured fisher surveys. Disaggregate by (i) species or species group; (ii) gear type; and (iii) ecosystem association (typically coral reef, seagrass, mangrove, or pelagic) using species-habitat associations from peer-reviewed literature, validated against local fisher knowledge where feasible. Where landing surveys cover only a fraction of trips, practitioners may calibrate coverage against provincial or regional statistics to derive an extrapolation factor.

b) Monetary valuation: resource rent. Resource rent is computed following the method defined in TG-3.2 Flows from Environment to Economy Section 3.5. A negative residual indicates that fishing costs exceed revenue under prevailing conditions and may be reported as a zero ecosystem service value with the negative figure disclosed in metadata. The resource rent method is consistent with the FAO Code of Conduct for Responsible Fisheries principles on economic sustainability of fisheries and with the SEEA EA treatment of market-based provisioning services.

c) Tiered implementation. Practitioners may begin at Tier 1 (national aggregate catch statistics with global or regional unit values transferred from comparable contexts) and progress to Tier 2 (locally compiled landings disaggregated by species, gear, and ecosystem, with domestically sourced cost data) or Tier 3 (vessel-level production accounts with site-specific capital stock valuation). Value-transfer accuracy is limited and may not be acceptable beyond preliminary accounts. Practitioners may consider flagging Tier 1 entries as indicative.

d) Data sources. FAO FishStat global capture production records provide the international benchmark. National fisheries authority landings registers, port samplers, and structured artisanal-fisher surveys provide the disaggregated detail required for ecosystem attribution.

3.7.3 Gleaning (intertidal hand-collection)

a) Physical measurement. Where direct catch records are unavailable, household survey instruments may be used to estimate per-collector annual harvest (kg/yr) by target species group. Aggregate across the eligible population within accessible distance of the providing ecosystem. Spatial proxy models — in which collection is modelled as a function of distance to the resource edge, accessible standing stock, and household demand parameters — may be used to extrapolate where survey coverage is incomplete.

b) Monetary valuation. Where gleaned products enter local markets, first-sale prices may be used to compute gross revenue and a resource rent computed analogously to wild-capture fisheries (Section 3.7.2). Where collection is predominantly for subsistence with no observed market transaction, practitioners may consider a substitute-cost approach — valuing the catch against the market price of the nearest commercial equivalent — and recording the result as a Category V (non-market) valuation in metadata.

c) Use table. Gleaning output typically flows to subsistence households rather than the formal fisheries sector. The use table should record this allocation distinctly to preserve the distributional information needed for livelihood and food-security analysis.

3.7.4 Wood and non-timber forest product (NTFP) provisioning from mangroves

Where aquaculture operations are sited in or adjacent to mangrove ecosystems — a common pattern for brackish-water shrimp and milkfish ponds — the mangrove area that remains intact may continue to provide wood and NTFP provisioning services (fuel wood, building poles, charcoal feedstock, honey, dye, traditional medicine) to surrounding communities. The provisioning-service account for mangrove wood is conceptually independent from the aquaculture account but should be compiled in the same accounting area to enable trade-off analysis between mangrove conversion for ponds and retained mangrove provisioning value.

a) Physical measurement. Where direct household survey data on fuel-wood collection are unavailable, practitioners may consider a spatial proxy model estimating per-household extraction as a function of distance from household to mangrove edge, accessible deadwood stock, and a baseline household demand parameter drawn from peer-reviewed literature. Aggregation across eligible households within an accessible distance band yields total annual collection. Practitioners may flag the use rate against a sustainable yield benchmark (commonly expressed as a function of standing biomass and rotation length) to check consistency with mangrove extent accounts.

d) Cross-account consistency. The use rate implied by the physical account must be cross-checked against extent and condition accounts for the providing mangrove ecosystem. A use rate exceeding sustainable yield implies declining mangrove biomass, and that decline should be reflected in the extent or condition account and metadata. Practitioners may consider flagging districts where mangroves have been substantially converted to aquaculture as excluded from the provisioning model.

3.7.5 Data quality and limitations

Provisioning-service quantification in coastal contexts is sensitive to several recurring data-quality issues that practitioners may consider documenting in account metadata:

This subsection presents candidate workflows. Practitioners may select among them according to the structure of the accounting area, the data available, and the policy questions the account is intended to support. The SEEA EA framework permits parallel compilation of cultivated and natural provisioning accounts in a single physical supply and use table, with monetary entries compiled where data permit.

Authors: [To be confirmed]

Reviewers: [To be confirmed]

Note: This circular addresses a priority addition identified in the February 2025 modular structure revision.