Maritime Transport and Ports

This Circular builds upon the following prerequisites:

• TG-0.1 General Introduction to Ocean Accounts — foundational framework for GOAP Technical Guidance, including core concepts, terminology, and accounting principles.

• TG-3.3 Economic Activity Relevant to the Ocean — general approach to compiling accounts for ocean-related economic activity, including industry classifications, supply and use tables, and the ocean economy thematic and extended account framework. The maritime transport accounts compiled under this Circular are a sector-specific application of the methods in TG-3.3.

Related Circulars (optional but recommended):

Readiness and sequencing. Whether a country is positioned to compile this account at all — mandate, data architecture, capacity and the order in which to build — is assessed under TG-0.8 Implementation Readiness Assessment, and is not restated here.

3.1 Maritime Transport Activities

3.1.1 Industry Classification Framework

Maritime transport activities are classified according to ISIC Revision 4.

Division 50 — Water Transport

This division encompasses the transport of passengers or freight over water, whether scheduled or not, distinguishing between sea-going vessels and inland waterway vessels based on vessel type.

Inland waterway transport (ISIC 502). For inland navigation emissions, compilers should refer to the IPCC 2006 Guidelines, Volume 2, Chapter 3, which provides default emission factors for water-borne navigation including inland vessels. Vessels operating in both inland and coastal environments should be classified by predominant area of operation. Compilers should document the classification rule in metadata and apply it consistently across the time series.

Supporting Activities (Division 52)

The “Coverage” column distinguishes ISIC classes that are mandatory components of maritime transport accounts (ISIC 5222 and the maritime-attributable share of ISIC 5224) from those that are supplementary. ISIC 5224 (Cargo Handling) covers both maritime and non-maritime cargo handling. Compilers should apply a maritime ratio to apportion the maritime share, as illustrated in the worked example in Section 3.7 using an illustrative 0.70 ratio.

(Note: ISIC Division 30, ship building [3011] and pleasure boats [3012], is excluded from TG-6.10 scope. Record these under general industry accounts.)

For accounting purposes, the commercial fleet may be disaggregated by vessel type. Table 3.1.1 below summarises the principal categories.

This disaggregation is important for emissions accounting because emission factors vary by vessel type, size, and engine configuration. The vessel classification should be used consistently across physical activity accounts, economic accounts, and emissions accounts. The Fourth IMO GHG Study (2020) provides emission factor data by vessel type and operating mode that can serve as a starting point where country-specific factors are not available.

3.1.3 Trade Flow Measurement

Maritime trade flows are measured through:

• Volume (physical): Tonnes loaded and unloaded at ports
• Value (monetary): Value of goods transported (CIF/FOB basis)
• Activity (operational): Vessel movements, port calls, cargo handling operations

Data sources include port authority records, customs declarations, automatic identification system (AIS) tracking, and shipping company reports. Satellite AIS covers most commercial vessels over 300 gross tonnes in major shipping lanes, though coverage in remote ocean areas, smaller vessel classes, and terrestrial AIS-predominant regions remains incomplete. Compilers should cross-check AIS-derived activity data against vessel registry sources such as UNCTAD’s Review of Maritime Transport and document coverage limitations in metadata.

3.2.1 Port Areas and Land Use

Port infrastructure accounting requires spatial delineation of port areas. Table 3.2.1 below summarises the main land-use components of a port.

Port areas should be mapped using consistent spatial references (see TG-4.1 Remote Sensing) and linked to the SEEA land cover and land use classifications. The port boundary should encompass the full operational area including anchorages, fairways, and approach channels.

3.2.2 Dredging and Land Reclamation

Dredging activities modify the seabed to maintain or create navigational channels and berthing areas. The distinction between capital and maintenance dredging determines SNA treatment:

Compilers should apply this rule to dredging expenditure records from port authorities and contractor invoices. Where invoices do not clearly distinguish the two, compilers should document the criterion used. For the fuller treatment of capital versus maintenance distinctions for coastal works, cross-reference TG-6.11 Coastal Infrastructure Accounting Section 3.2.4.

Physical measures:

• Volume of sediment removed (cubic metres)
• Disposal location (ocean dumping, beneficial reuse, confined disposal)
• Channel depth and width specifications

Dredge spoil as a material flow. Dredged sediment should be recorded as a material flow in the SEEA Central Framework physical flow accounts. SEEA CF paragraph 3.267 treats dredging material flows under physical flow accounting, with contaminated spoil recorded as a residual flow within waste accounts and unpolluted spoil excluded from the waste-flow boundary. Compilers should record dredge spoil volumes by disposal pathway and sediment quality classification.

Environmental considerations:

• Sediment quality (contaminant levels)
• Impacts on benthic habitats
• Turbidity and sedimentation effects

Land reclamation for port expansion should be recorded as a transformation of marine extent to land (cross-reference TG-3.1 Assets). Port expansion through reclamation may also trigger requirements under coastal infrastructure accounting (see TG-6.11 Coastal Infrastructure Accounting).

3.2.3 Port Capital Formation

Gross fixed capital formation in ports includes investment in:

• Breakwaters and seawalls
• Quay structures and berths
• Container handling equipment (cranes, straddle carriers)
• Warehouses and storage facilities
• Navigational aids and vessel traffic systems
• Environmental protection infrastructure (oil spill response, waste reception)

Capital formation should be recorded following SNA 2025 principles, distinguishing new construction and major improvements (gross fixed capital formation) from routine maintenance (intermediate consumption). Depreciation schedules vary by asset type: quay structures may have useful lives of 50 years or more, whilst handling equipment typically depreciates over 15—25 years. The perpetual inventory method (PIM) is the standard approach for compiling port capital stock.

3.2.4 Vessel Capital Stock

Vessels are produced assets that should appear in national balance sheets as transport equipment under SNA 2025 asset classification AN1131. Vessel capital stock is required for: (i) calculating consumption of fixed capital used to derive net value added in Table 3.7.1, and (ii) supporting complete asset accounting for the maritime transport industry.

Data sources for vessel capital stock:

• National vessel registries and maritime administration records (acquisition costs, vessel age, type)
• Lloyd’s Register / IHS Markit (now LSEG/Clarksons) maritime fleet databases (vessel characteristics, valuation benchmarks)
• Customs records on vessel imports and exports
• Shipping company financial statements (book values, depreciation schedules)

PIM application. Compilers should apply the perpetual inventory method to vessel acquisition costs using vessel-type-specific service lives and depreciation profiles (container vessels typically 20—30 years, bulk carriers and tankers 25—30 years, and passenger ferries 30—40 years). For the general PIM framework, see TG-3.1 Asset Accounts. The depreciation entry for ISIC 501 in Table 3.7.1 represents vessel depreciation derived through this PIM approach.

3.3.1 Greenhouse Gas Emissions

Following the SEEA Central Framework, air emissions accounts record the generation of emissions by resident economic units by type of substance.

GHG emissions from shipping include:

• Ship fuel consumption records
• AIS-derived activity data
• Port call statistics
• National fuel sales data with maritime allocation

The Fourth IMO GHG Study (2020) provides emission factor data by vessel type and operating mode. Compilers may also draw on the IPCC 2006 Guidelines, Volume 2, Chapter 3.

Table 3.3.1: Shipping emission calculation methods

Ballast water discharge is not an air emission or a SEEA residual air flow. It is a biological pressure with ecosystem condition implications. The accounting treatment for ballast water is set out in Section 3.5.1.

Residence principle application:

Reconciliation with IPCC national inventories. The SEEA-based residence attribution will differ from IPCC national inventory treatment, which excludes international marine bunker fuels from national totals and reports them as a memo item. Compilers should prepare a bridging table in metadata distinguishing SEEA-attributed shipping emissions from IPCC memo-item international marine bunker fuel quantities. For broader reconciliation between thematic emissions accounts and national climate reporting, see TG-2.8 Climate Indicators.

Flag-of-convenience and complex vessel ownership. Compilers should apply the following decision tree for residence attribution:

Practical sources include the IMO Global Integrated Shipping Information System (GISIS) and Lloyd’s Register / IHS Markit (LSEG/Clarksons) maritime databases. Open or international registries account for the majority of global gross tonnage, so most compiling countries will encounter Case 2 or Case 3 in practice.

Beyond GHGs, maritime transport releases air pollutants with local and regional health impacts:

IMO MARPOL Annex VI regulates these emissions and has established Emission Control Areas. The 2020 global sulphur cap of 0.50 per cent m/m has had a material effect on fuel composition and emissions profiles that should be reflected in time series accounts.

Underwater noise accounting is an emerging area where data availability and standardised methods remain under development. The IMO Guidelines for the Reduction of Underwater Noise from Commercial Shipping (MEPC.1/Circ.833) provide a voluntary framework, whilst regional initiatives such as JOMOPANS are developing monitoring methodologies. Compilers should record noise indicators where feasible and note limitations in metadata. For linkage to ecosystem condition assessment, see TG-2.1 Biophysical Indicators.

Maritime transport value added is calculated according to SNA 2025 principles:

Gross Value Added (GVA) = Output — Intermediate Consumption

For maritime transport industries (ISIC 50, 5222):

• Spill volume and substance type
• Location and environmental sensitivity
• Response costs
• Natural resource damage assessments
• Linkage to SEEA pollution flow accounts (TG-3.4 Flows from Economy to Environment)

Operational discharges (bilge water, cargo residues) remain a persistent source of chronic pollution that should be captured in flow accounts alongside acute events.

3.6 Compilation Procedure: Maritime Transport Supply-Use Table

Compiling maritime transport accounts follows a systematic procedure for extracting maritime transport sub-matrices from national supply and use tables, adapted from SNA 2025 Chapter 15 and the ocean economy thematic account compilation approach in TG-3.3 Economic Activity Relevant to the Ocean Section 3.4.

Step 1: Identify maritime transport industries by ISIC code. Using Table 3.1.1, identify all ISIC classes constituting maritime transport: Division 50, Class 5222, Class 5224 (port portion), and related industries. For each class, determine whether it is wholly maritime-related (ocean ratio = 1.0) or partially maritime-related (ocean ratio < 1.0).

Step 2: Extract maritime transport sub-matrices from national SUTs. From the balanced national supply and use tables, extract columns corresponding to maritime transport industries to create a maritime transport supply table and use table.

Excluding non-resident enterprise output. For countries that are major port hubs or transshipment centres, maritime transport columns may include services provided by non-resident enterprises. The residence principle requires excluding non-resident maritime output before deriving GVA. Practical data sources include balance of payments supplementary data on transportation services and port authority records of vessel nationality and operator residence. Cross-reference BPM6 paragraphs 10.73—10.88 on transportation services.

Step 4: Calculate Maritime Transport Direct GVA. For each maritime industry, multiply the industry’s gross value added from the Use Table by its maritime ratio:

$\text{Maritime Transport Direct GVA}=\sum _i({\text{GVA}}_i\times {\text{Maritime ratio}}_i)$Maritime Transport Direct GVA=i∑​(GVAi​×Maritime ratioi​)

Step 5: Compile employment accounts. Using labour input rows from the Use Table, calculate maritime transport employment by applying the same maritime ratios to employment data by industry.

Step 6: Derive trade flow indicators. From the Exports column in the Use Table, sum across maritime transport service products to calculate maritime transport service exports. From customs data, compile merchandise trade volumes and values passing through ports.

• National supply and use tables (primary source for GVA and output)
• Port authority statistical reports (cargo volumes, vessel calls, employment)
• Maritime administration records (vessel registries, seafarer certification)
• Structural business surveys (port and shipping company financial data)
• Customs declarations (trade values and volumes)
• AIS tracking data (vessel activity, voyage data)
• Fuel sales records (maritime fuel consumption for emissions)
• Balance of payments transport services supplementary data (for resident/non-resident enterprise attribution)

3.7 Worked Example: Synthetic Port/Shipping Account

This section presents a worked example for a synthetic medium-income coastal state (“Country B”) with a total GDP of approximately USD 80 billion, total employment of 15 million persons, and two major ports handling combined cargo volumes of 45 million tonnes per year. The example illustrates the mixed-industry apportionment for ISIC 5224. It applies an illustrative maritime ratio of 0.70.

Table 3.7.1: Country B Maritime Transport Account — Production Account

All monetary values in millions of USD at current prices. The ISIC 5224 column reports the maritime-attributable share after applying the 0.70 maritime ratio (total ISIC 5224 output of 350 x 0.70 = 245). The depreciation entry for ISIC 501 (USD 120 million) reflects vessel capital consumption derived through the perpetual inventory method described in Section 3.2.4.

Table 3.7.2: Country B Maritime Transport Employment

Sea transport employment is measured on a residence basis as set out in Section 3.4.2. For Country B, seafarer employment from MLC flag-state data has been adjusted to a residence basis using the BIMCO/ICS Seafarer Workforce Report (2021) national supply estimates.

Table 3.7.3: Country B Maritime Transport Emissions

Panel A: Greenhouse gases (tonnes CO2e, AR6 GWP100)

Note (biogenic CH4): The CH4 row applies the AR6 GWP100 of 29.8 for fossil-sourced methane. As biofuel blends and bio-LNG become material under IMO’s 2023 GHG Strategy fuel-mix scenarios, biogenic CH4 should be reported separately at GWP100 = 27.0 (AR6 non-fossil value). Compilers should document the fuel-type split and apply the corresponding GWP factor for each CH4 emission stream once biofuel uptake is material.

Panel B: Air pollutants (tonnes; illustrative, derived from the same fuel-consumption activity data using EMEP/EEA emission factors)

The figures in Panel B are derived from the same fuel-consumption activity data used for Panel A, applying air pollutant emission factors from the EMEP/EEA Air Pollutant Emission Inventory Guidebook (2019), Chapter 1.A.3.d. Emission factors applied at the IMO 2020 global 0.50% sulphur cap (non-ECA). Compilers applying this method to pre-2020 data or ECA-regulated routes should substitute factors consistent with the applicable sulphur limit. For linkage to health impact assessment, see TG-2.7 Pollution and Other Flows.

Table 3.7.4: Country B Port Infrastructure Capital Stock (PIM approach)

All monetary values in millions of USD at current replacement cost. The net capital stock of USD 1,270 million represents approximately 4.2 times the annual GVA from port services (USD 300 million). Vessel capital stock for ISIC 501 (not shown: see Section 3.2.4) is compiled separately under SNA asset class AN1131. The compilation applies vessel-type-specific PIM parameters. The USD 60 million annual depreciation on port infrastructure is lower than port-services depreciation in Table 3.7.1 (USD 85 million) because ISIC 5222 depreciation also covers fixed assets outside this table; compilers should reconcile the two and document the USD 25 million difference by asset type.