Resource Efficiency Indicators

1. Outcome

This Circular provides comprehensive guidance on compiling resource efficiency indicators from ocean accounts. Resource efficiency indicators measure the relationship between economic outputs and natural resource inputs, revealing how effectively ocean-related industries transform natural capital into economic value. These indicators are essential for tracking progress toward circular ocean economies, assessing decoupling of economic growth from resource extraction, measuring alignment with SDG targets 8.4 (resource efficiency and decoupling) and 12.2 (sustainable resource management), and demonstrating green growth in ocean sectors. Upon completing this Circular, readers will understand the conceptual framework for resource efficiency indicators; compilation procedures for deriving material efficiency indicators for fish, water, and energy; methods for computing decoupling indicators that track the relationship between economic growth and resource use; approaches to circular economy indicators for waste, recycling, and resource recovery; and practical applications to sector-specific efficiency metrics for fisheries, aquaculture, maritime transport, and offshore energy. The guidance draws on the economic activity measures established in TG-2.5 Ocean Economy Structure and TG-3.3 Economic Activity, the physical flow accounts described in TG-3.2 Flows from Environment to Economy and TG-3.3 Flows from Economy to Environment, and the statistical standards framework presented in TG-0.2 Standards Overview. These indicators support the monitoring of Sustainable Development Goal targets and inform policy decisions aimed at achieving greater productivity from ocean resources while reducing environmental pressures. The resource efficiency indicators compiled using this guidance can feed directly into budget and planning processes described in TG-1.1 Budget Processes.

2. Requirements

This Circular requires familiarity with:

• TG-0.1 General Introduction to Ocean Accounts -- for the conceptual framework connecting ecosystems, flows, and economic activity
• TG-0.2 Overview of Relevant Statistical Standards -- for the international statistical standards underpinning ocean accounting, including SNA 2025, SEEA CF, and classification systems
• TG-3.3 Economic Activity -- for the economic measures (output, value added, GDP) that serve as the numerator in efficiency indicators, and for supply and use table structures that provide consistent economic data

For additional context on physical flow accounting, see TG-3.2 Flows from Environment to Economy. For guidance on linking efficiency indicators to environmental asset stocks, see TG-3.1 Asset Accounts. For guidance on residual flows that inform circular economy indicators, see TG-3.4 Flows from Economy to Environment.

3. Guidance Material

Resource efficiency represents a cornerstone concept in sustainable development policy, linking economic performance to environmental resource use^[1]. The SEEA Central Framework identifies resource efficiency and productivity indicators as a key application of environmental-economic accounting, noting that topics covered include "resource efficiency and productivity indicators, decomposition analysis, analysis of net wealth and depletion, sustainable production and consumption, input-output analysis and general equilibrium modelling"^[2]. The SEEA Applications and Extensions publication provides additional detailed guidance on constructing and interpreting resource efficiency indicators within the environmental-economic accounting framework; compilers should consult that publication alongside this Circular for extended methodological guidance^[3]. For ocean accounting, resource efficiency indicators reveal whether ocean-based economic activities are generating more value from less resource extraction--a fundamental test of progress toward sustainable ocean economies.

This section establishes a framework for resource efficiency indicators (Section 3.1), describes material efficiency indicators for fish, water, and energy (Section 3.2), presents decoupling indicators that compare economic and resource trends (Section 3.3), introduces circular economy indicators applicable to ocean sectors (Section 3.4), provides guidance on sector-specific efficiency metrics (Section 3.5), presents a step-by-step compilation procedure (Section 3.6), and illustrates the approach with worked examples (Section 3.7). The methodology draws on SEEA Central Framework guidance on physical flow accounts and combined presentations^[4], SEEA Energy guidance on energy intensity and efficiency indicators^[5], SDG indicator methodologies for targets 8.4 and 12.2^[6], and SEEA-Water guidance on water productivity and intensity^[7].

3.1 Resource Efficiency Framework

Resource efficiency indicators express the relationship between economic outputs and natural resource inputs. The SEEA Central Framework establishes that combined presentations of physical and monetary data "structure information in a manner that supports the derivation of combined indicators, for example, decoupling indicators which track the relationship between the use of resources and growth in production and consumption"^[8]. This conceptual foundation enables the construction of indicators that compare trends in economic activity (measured in monetary terms) with trends in resource use (measured in physical terms).

Decision use cases

Resource efficiency indicators for the ocean economy serve four primary decision contexts:

Circular ocean economy tracking -- governments committed to circular economy transitions require indicators that demonstrate whether ocean industries are reducing material throughput per unit of output, increasing recycling and reuse rates, and closing material loops. The European Commission's Circular Economy Action Plan and similar national strategies call for monitoring progress through material flow indicators, waste generation rates, and recycling performance metrics^[9].

Decoupling analysis -- SDG Target 8.4 explicitly requires countries to "improve progressively, through 2030, global resource efficiency in consumption and production and endeavour to decouple economic growth from environmental degradation"^[10]. Resource efficiency indicators provide the empirical evidence to demonstrate whether ocean economy growth is accompanied by declining resource intensity (relative decoupling) or absolute reductions in resource extraction (absolute decoupling).

SDG 12 reporting -- SDG Target 12.2 calls for achieving "sustainable management and efficient use of natural resources" by 2030^[11]. The SDG indicator framework includes material footprint per capita and per GDP (indicators 8.4.1 and 12.2.1) as headline measures of progress. Ocean economy resource efficiency indicators contribute directly to national reporting under these frameworks.

Green growth measurement -- ministries of finance and planning agencies increasingly require evidence that ocean economy growth is compatible with environmental sustainability objectives. Resource efficiency indicators provide quantified metrics for budget presentations, medium-term expenditure frameworks, and national development plans, demonstrating that ocean sectors are achieving productivity improvements without proportional increases in environmental pressure.

Basic indicator structure

Resource efficiency indicators follow a general ratio structure:

Resource Efficiency = Economic Output / Resource Input

Where:

• Economic output may be measured as gross value added (GVA), gross output, or GDP, drawn from the economic accounts described in TG-2.5 Ocean Economy Structure and TG-3.3 Economic Activity
• Resource input is measured in physical terms--tonnes of fish extracted, cubic metres of water abstracted, joules of energy consumed--drawn from physical flow accounts described in TG-3.2 Flows from Environment to Economy

The reciprocal formulation--resource intensity--expresses resource input per unit of economic output:

Resource Intensity = Resource Input / Economic Output

Both formulations provide valid analytical perspectives. Resource efficiency emphasises productivity gains (higher values indicate improvement), while resource intensity emphasises resource requirements (lower values indicate improvement). The SEEA Energy notes that "indicators of energy efficiency, energy expenditures by different industries and households, and energy intensity" can be derived through combined presentations^[12].

Selecting the economic measure

The choice of economic measure in the numerator (or denominator for intensity indicators) affects interpretation and should be made deliberately. Three principal measures are available from the ocean economy thematic and extended accounts described in TG-3.3 Economic Activity Section 3.4:

• Gross value added (GVA) is typically preferred for industry-level analysis because it excludes intermediate consumption, providing a cleaner measure of the value created by an industry from its resource inputs. GVA enables comparison across industries of different sizes and structures. The derivation of GVA from supply and use tables is described in TG-2.5 Section 3.7.
• Gross output may be more appropriate for productivity analysis within a single industry, as it captures the total volume of production and thus better reflects physical throughput. However, gross output can be inflated by high intermediate consumption, potentially misrepresenting efficiency.
• GDP is appropriate only for economy-wide analysis of the total ocean economy's resource efficiency, as it aggregates across all industries.

Compilers should document which economic measure is used and ensure consistency across time series. When comparing efficiency across countries or industries, the same economic measure should be employed to ensure valid comparisons.

Dimensions of resource efficiency

Resource efficiency can be analysed across multiple dimensions^[13]:

1. Material efficiency -- the physical quantity of natural resources (fish, minerals, water) required per unit of economic output
2. Energy efficiency -- the quantity of energy required per unit of economic output or per unit of physical output
3. Water efficiency -- the volume of water abstracted or consumed per unit of economic output
4. Carbon efficiency -- greenhouse gas emissions per unit of economic output (addressed in TG-2.8 Climate Indicators)

For ocean accounting, material efficiency is particularly relevant for fisheries and mineral extraction, energy efficiency for maritime transport and offshore energy, and water efficiency for aquaculture and coastal industries.

Resource Efficiency Indicator Specifications

Table 1 summarises the core resource efficiency indicator types, their formulations, ocean applications, and data requirements.

Table 1: Core resource efficiency indicator specifications for ocean applications

Analytical levels

Resource efficiency indicators can be compiled at multiple analytical levels:

• Economy-wide -- comparing total ocean economy GVA to total ocean resource use
• Industry-level -- comparing value added or output for specific ocean industries (fishing, shipping, offshore energy) to resource inputs for those industries
• Establishment-level -- comparing output of individual enterprises to their resource consumption (typically available only through survey or administrative data)

The industry-level analysis is typically most useful for policy, as it reveals differential efficiency across ocean sectors and identifies opportunities for improvement. The SEEA Energy provides example analyses at the industry level, showing "energy intensities for selected industries" that enable comparison across sectors^[14].

3.2 Material Efficiency Indicators

Material efficiency indicators measure the relationship between physical resource extraction and economic output. For ocean resources, the primary materials of interest are fish and other aquatic biomass, seawater (for desalination and industrial use), and seabed minerals.

Fish productivity

Fish productivity indicators relate the value of fishing industry output to the physical quantity of fish extracted. Following SEEA CF guidance on aquatic resources^[15], the key physical measure is gross catch--the total live weight of fish caught, including discarded catch but excluding pre-catch losses. This measure aligns with the physical flow accounts described in TG-3.2 Flows from Environment to Economy.

Key fish productivity indicators include:

Value added per tonne of catch -- the gross value added of the fishing industry divided by total catch weight:

Fish Productivity ($/tonne) = Fishing Industry GVA / Gross Catch (tonnes)

This indicator reveals how much economic value is generated per unit of fish extracted. Higher values may indicate higher-value species composition, more value-added processing, or improved market access. However, compilers should be aware that high economic efficiency is compatible with overfishing if prices rise as stocks decline--a phenomenon that can occur when scarcity drives up market prices for depleted species. For this reason, fish productivity indicators should always be interpreted alongside sustainability indicators. SDG indicator 14.4.1 measures "proportion of fish stocks within biologically sustainable levels"^[16], and the fisheries stock assessment methods described in TG-6.7 Fisheries Stock Assessment provide complementary measures of biological sustainability. A comprehensive assessment of fisheries resource efficiency requires examining both economic productivity and stock sustainability trends in parallel, ensuring that apparent efficiency gains are not masking resource depletion.

Catch per unit of effort (CPUE) -- while not strictly an economic efficiency indicator, CPUE relates physical catch to fishing effort and provides insight into the productivity of fishing operations and the abundance of fish stocks. CPUE is addressed in detail in TG-6.7 Fisheries Stock Assessment.

Sustainable yield ratio -- comparing actual extraction to estimated maximum sustainable yield (MSY) for managed fish stocks, providing a complementary perspective on resource sustainability.

Water productivity

Water productivity indicators relate economic output to water abstraction and consumption. The SEEA-Water framework provides detailed guidance on water intensity and productivity measurement^[17].

For ocean contexts, relevant water productivity indicators include:

Aquaculture water productivity -- the value added of aquaculture production divided by water use (intake volume for flow-through systems, or pond area times depth for standing water systems):

Aquaculture Water Productivity = Aquaculture GVA / Water Use (m³)

This indicator is relevant for aquaculture operations where water efficiency is a management priority, as described in TG-3.9 Aquaculture Accounts.

Desalination efficiency -- the ratio of freshwater output to energy input in desalination operations, relevant for coastal communities dependent on desalination.

Industrial water intensity -- for coastal industries using seawater for cooling or processing, the volume of water abstracted per unit of output.

The SEEA-Water notes that water efficiency "can be improved from the demand as well as the supply side" and that physical supply and use tables provide the information base for monitoring water efficiency^[18].

Energy productivity

Energy productivity indicators relate economic output to energy consumption. The SEEA Energy framework provides extensive guidance on energy intensity indicators^[19].

Key ocean-related energy productivity indicators include:

Maritime transport energy intensity -- energy consumption per tonne-kilometre of freight or per passenger-kilometre:

Shipping Energy Intensity = Energy Use (joules) / Transport Output (tonne-km)

This indicator is central to monitoring decarbonisation progress in the maritime sector and relates to climate indicators described in TG-2.8 Climate Indicators.

Offshore energy extraction efficiency -- for offshore oil and gas, the ratio of energy extracted to energy consumed in extraction operations (energy return on energy invested, or EROEI). See TG-3.10 Offshore Energy Accounts for detailed guidance.

Fishing fleet fuel efficiency -- fuel consumption per tonne of catch, relevant for both cost efficiency and greenhouse gas emission reduction.

The SEEA Energy notes that energy use combined with economic data enables derivation of "energy use per unit of GDP"^[20], which can be adapted to the ocean economy by relating ocean sector energy use to ocean sector GVA.

3.3 Decoupling Indicators

Decoupling indicators track the relationship between economic growth and resource use over time, revealing whether an economy is achieving more output with less environmental pressure. SDG Target 8.4 explicitly calls upon countries to "improve progressively, through 2030, global resource efficiency in consumption and production and endeavour to decouple economic growth from environmental degradation"^[21].

Concept of decoupling

Decoupling occurs when the growth rate of an environmental variable (resource use, emissions, waste generation) is lower than the growth rate of the relevant economic variable (GDP, value added, output)^[22]. Two forms are distinguished:

1. Relative decoupling -- the environmental variable continues to grow, but at a slower rate than economic output. Resource intensity declines, but total resource use increases.

2. Absolute decoupling -- the environmental variable declines in absolute terms while economic output grows. This represents genuine reduction in environmental pressure alongside economic growth.

The SEEA CF notes that combined presentations "support the derivation of combined indicators, for example, decoupling indicators which track the relationship between the use of resources and growth in production and consumption"^[23].

Computing decoupling indicators

A decoupling factor can be computed as:

Decoupling Factor = 1 - (Resource Use Growth Rate / Economic Output Growth Rate)

Where:

• A positive decoupling factor indicates relative decoupling
• A decoupling factor > 1 indicates absolute decoupling
• A negative factor indicates increasing resource intensity ("recoupling")

Alternatively, an elasticity formulation expresses the responsiveness of resource use to economic growth:

Resource Elasticity = % Change in Resource Use / % Change in Economic Output

An elasticity less than 1 indicates relative decoupling; a negative elasticity with positive economic growth indicates absolute decoupling.

Methodological considerations for time period selection

Decoupling indicators are sensitive to the time period selected and to economic cycles, particularly in industries subject to natural variability such as fisheries. Compilers should consider the following methodological guidance when computing and presenting decoupling indicators:

• Peak-to-peak or trough-to-trough comparison -- for cyclical industries such as fishing, where catch volumes fluctuate with stock dynamics and environmental conditions, comparing equivalent phases of the cycle (e.g., peak-to-peak) avoids misleading trend signals that merely reflect cyclical position.
• Rolling averages -- using three-year or five-year rolling averages smooths annual variability and reveals underlying trends more reliably than single-year comparisons.
• Minimum time horizon -- decoupling assessments generally require at least five years of data to distinguish genuine structural trends from short-term fluctuations. Longer time series (ten or more years) are preferable for robust conclusions.
• Short-term versus long-term interpretation -- short-term decoupling may reflect temporary factors (economic recession reducing demand, or a strong recruitment year inflating catch) rather than genuine structural change. Compilers should present both short-term (five-year) and long-term (ten-year or longer) decoupling assessments where data permit, and clearly distinguish between the two in reporting.

Ocean economy decoupling indicators

For ocean accounting, key decoupling indicators include:

Fish extraction decoupling -- comparing growth in fishing industry GVA to growth in fish catch tonnage:

Fish Decoupling Factor = 1 - (Fish Catch Growth Rate / Fishing GVA Growth Rate)

Positive values indicate that the fishing sector is generating more value from each tonne of fish extracted--potentially through higher prices, better species mix, or more value-added processing. This indicator should be interpreted alongside stock sustainability indicators from TG-6.7 Fisheries Stock Assessment.

Maritime emissions decoupling -- comparing growth in shipping sector GVA to growth in greenhouse gas emissions:

Shipping Emissions Decoupling = 1 - (Emissions Growth Rate / Shipping GVA Growth Rate)

This indicator tracks progress toward the International Maritime Organization's decarbonisation goals and relates to the climate indicators described in TG-2.8 Climate Indicators.

Material footprint decoupling -- SDG indicators 8.4.1 and 12.2.1 measure material footprint (per capita and per GDP)^[24], which can be computed for ocean-related materials to track decoupling at the economy-wide level.

3.4 Circular Economy Indicators

Circular economy indicators measure the extent to which economic systems reduce waste, reuse materials, and recycle resources--moving from linear "take-make-dispose" models toward circular flows. SDG Target 12.5 aims to "substantially reduce waste generation through prevention, reduction, recycling and reuse"^[25].

Circular economy concepts

The circular economy model seeks to maintain the value of products, materials, and resources in the economy for as long as possible, minimising waste and resource extraction^[26]. For ocean sectors, circular economy principles apply to:

• Fishing and aquaculture -- reducing discards and bycatch, utilising fish processing waste for feed or other products
• Maritime transport -- extending vessel lifetimes, recycling ship materials at end of life
• Offshore energy -- decommissioning and recycling offshore platforms, repurposing infrastructure

These applications relate to the flows from economy to environment described in TG-3.4 Flows from Economy to Environment.

Waste and recycling indicators

Key circular economy indicators for ocean sectors include:

Discard ratio in fisheries -- the proportion of catch that is discarded rather than landed:

Discard Ratio = Discarded Catch / Gross Catch

The SEEA CF treats discarded catch as "natural resource residuals"--flows that are extracted but immediately returned to the environment^[27]. SDG indicator 14.4.1 and related fisheries management frameworks track bycatch and discard reduction.

Fish waste utilisation rate -- the proportion of fish processing residues (heads, bones, offal) that are converted to useful products (fishmeal, fish oil, fertiliser):

Waste Utilisation Rate = Residues Utilised / Total Processing Residues

National recycling rate -- SDG indicator 12.5.1 measures the national recycling rate^[28], which can be disaggregated for materials relevant to ocean sectors (plastics, metals from shipbuilding).

Marine litter generation -- flows of waste to the marine environment, representing a failure of circular economy systems. Addressed in TG-2.7 Pollution Flows and TG-6.12 Marine Litter.

Resource recovery indicators

For extractive ocean industries, resource recovery indicators measure the proportion of in-situ resources that are successfully captured:

Extraction efficiency for minerals -- the proportion of identified reserves that are extracted over the lifetime of an operation, relevant for seabed mining and offshore hydrocarbons.

Energy recovery in offshore operations -- the proportion of potential energy content captured in oil and gas extraction, accounting for losses from flaring, venting, and fugitive emissions. See TG-3.10 Offshore Energy Accounts for detailed guidance.

3.5 Sector-Specific Efficiency Indicators

Different ocean sectors require tailored efficiency indicators that reflect their specific resource use patterns and economic characteristics. This section provides guidance on key indicators for fisheries, aquaculture, maritime transport, and offshore energy.

Fisheries efficiency indicators

For the fishing industry, key efficiency indicators include:

Table 2: Key fisheries efficiency indicators

The relationship between these indicators and sustainable yield is addressed in TG-6.7 Fisheries Stock Assessment.

Aquaculture efficiency indicators

For aquaculture, efficiency indicators focus on feed conversion, water use, and energy intensity:

Table 3: Key aquaculture efficiency indicators

Detailed guidance on aquaculture accounting is provided in TG-3.9 Aquaculture Accounts.

Maritime transport efficiency indicators

For shipping and maritime transport, efficiency indicators align with international decarbonisation frameworks:

Table 4: Key maritime transport efficiency indicators

The International Maritime Organization's greenhouse gas strategy establishes targets for reducing carbon intensity of international shipping^[29].

Offshore energy efficiency indicators

For offshore energy extraction, efficiency indicators address both conventional and renewable energy:

Table 5: Key offshore energy efficiency indicators

Detailed guidance on offshore energy accounting is provided in TG-3.10 Offshore Energy Accounts.

3.6 Compilation Procedure

Compiling resource efficiency indicators requires a systematic procedure for extracting data from ocean economy accounts and physical flow accounts, computing ratios, and presenting results. The procedure described below follows the SEEA Central Framework guidance on combined presentations and indicator derivation^[30].

Step-by-step compilation

Step 1: Identify ocean economy industries and extract GVA data. Using the ocean economy supply and use tables compiled under TG-3.3 Economic Activity, extract the gross value added row for each ocean industry. This provides the economic measure (denominator for intensity indicators, numerator for productivity indicators). The extraction procedure is described in TG-2.5 Ocean Economy Structure Section 3.7, Steps 2-5.

Step 2: Compile physical flow accounts for natural resource inputs. Following TG-3.2 Flows from Environment to Economy, compile physical supply and use tables recording:

• Fish catch (tonnes, live weight) by fishing industry
• Water abstraction (cubic metres) by aquaculture and coastal industries
• Energy consumption (joules or tonnes oil equivalent) by maritime transport, fishing, and offshore energy industries

The physical flow accounts should be compiled for the same reference period and industry classification as the monetary accounts to ensure consistency.

Step 3: Match physical flows to industries. For each ocean industry, identify the corresponding physical resource inputs from the physical supply and use tables. The industry classification in the physical accounts must align with the industry classification in the monetary accounts. Where classifications differ, use concordance tables or proportional allocation methods to achieve consistency. Common challenges include disaggregating offshore energy from total energy extraction and estimating the coastal tourism share of total accommodation water use.

Step 4: Compute resource efficiency ratios. For each industry and resource type, compute the efficiency ratio:

Resource Efficiency = GVA (currency units) / Physical Input (physical units)

Or the intensity ratio:

Resource Intensity = Physical Input (physical units) / GVA (currency units)

Document the units clearly (e.g., "USD per tonne of fish caught" or "joules per USD of shipping GVA").

Step 5: Compile time series and compute growth rates. For decoupling analysis, compile resource efficiency indicators for multiple years (minimum five years recommended). Compute annual growth rates for both economic output and physical input variables. Apply the decoupling formulas from Section 3.3 to derive decoupling factors or elasticities.

Step 6: Present results with context. Resource efficiency indicators should be presented alongside:

• The absolute levels of both numerator and denominator (to avoid misleading interpretations)
• Benchmark comparisons (national average, international comparcomparisons, historical trends)
• Contextual information on policy drivers, structural changes, or data quality limitations

The presentation formats in Section 3.7 provide templates for reporting.

3.7 Worked Examples

This section presents worked examples illustrating the compilation and interpretation of resource efficiency indicators for a hypothetical medium-income coastal state ("Country B"). All monetary values are expressed in US dollars; physical quantities use standard SI units.

Example 1: Marine fishing material productivity

Context: Country B's marine fishing industry reported the following data for 2023 and 2024:

Computation:

Fish productivity (2023):

180,000,000 USD / 120,000 tonnes = 1,500 USD/tonne

Fish productivity (2024):

190,000,000 USD / 115,000 tonnes = 1,652 USD/tonne

Productivity change:

(1,652 - 1,500) / 1,500 × 100 = 10.1% increase

Discard ratio (2023):

24,000 / 120,000 = 20%

Discard ratio (2024):

20,000 / 115,000 = 17.4%

Interpretation: Fish productivity increased by 10.1 per cent between 2023 and 2024, while total catch declined by 4.2 per cent. This suggests improved economic efficiency--the industry generated more value per tonne of fish extracted. The declining discard ratio (from 20 per cent to 17.4 per cent) indicates progress toward circular economy principles, with a larger proportion of catch being landed rather than discarded. However, compilers should verify whether the productivity increase reflects sustainable management (higher-value species, better processing) or scarcity effects (rising prices for depleted stocks). Cross-referencing with stock assessment data from TG-6.7 would provide this context.

Example 2: Aquaculture water productivity

Context: Country B's marine aquaculture industry (primarily shrimp and finfish) reported:

Computation:

Water productivity (2023):

135,000,000 USD / 900,000,000 m³ = 0.15 USD/m³

Water productivity (2024):

145,000,000 USD / 920,000,000 m³ = 0.158 USD/m³

Productivity change:

(0.158 - 0.15) / 0.15 × 100 = 5.3% increase

Output per water unit (2023):

45,000 tonnes / 900,000,000 m³ = 0.05 kg/m³

Output per water unit (2024):

48,000 tonnes / 920,000,000 m³ = 0.052 kg/m³

Interpretation: Aquaculture water productivity improved by 5.3 per cent, indicating that the industry generated more economic value per cubic metre of water used. Physical output per water unit also increased slightly (from 0.05 to 0.052 kg/m³), suggesting genuine improvements in water use efficiency rather than price effects alone. This progress aligns with SDG Target 12.2 on efficient use of natural resources. The modest increase in total water use (2.2 per cent) coupled with a 6.7 per cent increase in production demonstrates relative decoupling of aquaculture growth from water extraction.

Example 3: Maritime transport energy intensity and decoupling

Context: Country B's maritime transport sector (sea and coastal freight and passenger transport) reported:

Computation:

Energy intensity (2024):

840,000 toe / 490,000,000 USD = 1.71 toe per million USD GVA

Or per physical output:

840,000 toe / 162,000,000,000 tonne-km = 5.19 toe per million tonne-km

Five-year GVA growth (2019-2024):

(490 - 420) / 420 × 100 = 16.7%

Five-year energy consumption growth:

(840 - 850) / 850 × 100 = -1.2%

Decoupling factor:

1 - (-1.2% / 16.7%) = 1.07

Interpretation: Country B's maritime transport sector achieved absolute decoupling between 2019 and 2024: GVA grew by 16.7 per cent while energy consumption declined by 1.2 per cent. The decoupling factor of 1.07 (>1) confirms absolute decoupling. This progress likely reflects fleet modernisation, improved operational efficiency, and potentially a shift in cargo mix toward higher-value goods. The energy intensity per tonne-km declined from 5.86 toe/million tonne-km in 2019 to 5.19 in 2024 (11.4 per cent improvement), demonstrating genuine efficiency gains. This performance contributes to national progress under SDG Target 8.4 and aligns with the International Maritime Organization's greenhouse gas reduction strategy. The temporary dip in 2020 (COVID-19 pandemic) was followed by sustained recovery with improving efficiency trends.

Example 4: Ocean economy-wide decoupling analysis

Context: Country B's total ocean economy reported the following aggregates over a ten-year period:

Computation:

Ten-year growth rates (2015-2024):

• Ocean GVA: (1,950 - 1,450) / 1,450 × 100 = 34.5%
• Fish catch: (125,000 - 135,000) / 135,000 × 100 = -7.4%
• Energy use: (2,300 - 2,100) / 2,100 × 100 = 9.5%
• Water abstraction: (2,050 - 1,800) / 1,800 × 100 = 13.9%

Decoupling factors:

• Fish: 1 - (-7.4% / 34.5%) = 1.21 (absolute decoupling)
• Energy: 1 - (9.5% / 34.5%) = 0.72 (relative decoupling)
• Water: 1 - (13.9% / 34.5%) = 0.60 (relative decoupling)

Resource elasticities:

• Fish: -7.4% / 34.5% = -0.21 (absolute decoupling)
• Energy: 9.5% / 34.5% = 0.28 (relative decoupling)
• Water: 13.9% / 34.5% = 0.40 (relative decoupling)

Interpretation: Country B's ocean economy achieved absolute decoupling from fish extraction and relative decoupling from energy and water use over the ten-year period. The negative fish elasticity (-0.21) indicates that ocean economy growth was accompanied by declining fish catch--a positive outcome if fishing pressure was previously excessive. The low energy elasticity (0.28) means that a 1 per cent increase in ocean GVA was associated with only a 0.28 per cent increase in energy consumption, demonstrating substantial efficiency improvement. Water elasticity was higher (0.40), suggesting room for further improvement in water productivity. These results can be reported under SDG indicators 8.4.1 and 12.2.1, demonstrating progress toward resource efficiency targets. The patterns also inform budget presentations under TG-1.1, providing evidence that ocean economy investment is yielding environmental as well as economic returns.

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: Volunteers sought--this circular covers a broad technical area that would benefit from expertise in fisheries economics, maritime transport economics, and energy economics

Reviewers: Technical Expert Group review pending

5. References