Measuring fish stock depletion

The 2025 System of National Accounts (SNA) introduces the recording of natural resource depletion as a cost of production, creating a need for new methods to measure the use of renewable natural assets. The Office for National Statistics (ONS) has already developed experimental depletion estimates for non-renewable resources, including oil, gas, coal, and minerals. This project will extend that work to fish stocks, helping to ensure compliance with the 2025 SNA and supporting ONS’s international leadership in natural capital accounting.

The project will investigate the data, methods, and valuation approaches needed to account for fish depletion. Key questions include data availability, how renewable resource depletion differs from non-renewable depletion, how sustainable use should be defined, and how depletion should be valued within the National Accounts framework.

A further objective is to develop estimates that are consistent with existing National Accounts time series, including a historical series extending back to the 1950s. By improving the measurement of renewable natural capital, the project will support the development of depletion-adjusted measures such as Net Domestic Product (NDP) and provide a stronger basis for assessing sustainable economic growth.

The project will begin with a review of the literature on natural capital accounting and the valuation of renewable resource depletion, identifying suitable frameworks and methods for application to fish stocks.

The research will then develop a long-run physical account for UK fish resources. This will involve assembling data on fish stocks and catches, working closely with organisations including Defra, the Marine Management Organisation (MMO), the Centre for Environment, Fisheries and Aquaculture Science (Cefas), and Seafish. Physical measurements will be combined with estimates of regeneration, population growth, and harvesting rates to construct a consistent time series of fish stock depletion and assess its sustainability.

The project will then estimate the monetary value of depletion. Historical fish price data will be compiled, accounting for differences across species and over time. Alternative valuation approaches will be assessed, including the resource rent method used by ONS for fossil fuels and methods developed for ecosystem service valuation. The suitability of these approaches for integration into natural capital accounts will be evaluated.

Supporting better policy decisions
This project will help improve understanding of the economic costs of natural resource depletion by developing measures that can be incorporated into the National Accounts. By accounting for depletion alongside other costs of production, policymakers will be better able to assess the long-term sustainability of economic activity and gauge how resilient that activity — and the policies supporting it — would be to future resource shocks. The work is of direct interest to stakeholders including HM Treasury, Defra, the UN, and the OECD.

Improving measures of sustainable growth
The research will support the development of Net Domestic Product (NDP), providing a complementary measure to GDP that reflects changes in natural capital and aligns with the inclusive wealth principles set out in the Dasgupta Review. Comparing GDP and NDP will provide a more complete picture of sustainable economic growth and well-being.

Advancing international best practice
The findings will also contribute to ONS implementation of the 2025 System of National Accounts (SNA) and strengthen its international leadership in the measurement of depletion through engagement with other national statistical institutes and the wider research community. The resulting evidence base will support better-informed economic and environmental policy decisions.