Groupe de travail chargé de coordonner les statistiques des pêches (CWP)

Reference harmonization

The harmonization of statistical data from capture fisheries and aquaculture is an essential component in the collation of national, regional and global statistics (Fig. 1) and the development of the data value chain. CWP has long supported and fostered the development of data harmonization which involves inter alia the implementation of standard concepts and classifications, the reporting of statistics through national or regional data forms and questionnaires, and the reconciling of differences in the data. With recent progress in digital technologies, CWP parties and national agencies with a remit for fishery and/or aquaculture statistics are increasingly collecting, reporting and disseminating statistical data using electronic systems which are generally web-based and often developed for an agency’s purpose using specific requirements, data structures and coding. As a result, the statistical concepts, reference data and classifications associated with statistical data may differ between national agencies and regional and international organizations. Such differences may limit the exchange, collation and wider use of the data and their integration in the data value chain. Data harmonization may not be straightforward if mappings to concepts and standards vary among organizations or there is inadequate documentation of their use along the data value chain.

New requirements and procedures for data harmonization will also be needed to integrate fishery and aquaculture statistics derived from data from emerging technologies such as satellite-based Automatic Identification System (AIS, e.g. Taconet et al., 2019), Visible Infrared Imaging Radiometer Suite (VIIRS) and Synthetic Aperture Radar systems (SAR). In some cases, statistical data may need to be mapped to common standards and classifications prior to their wider use and the time required for such mapping and data harmonization may grow significantly if an agency reports to, or uses data from, multiple organizations which may use different standards and classifications.

Figure 1. Generalized scheme for the harmonization of capture fishery and aquaculture statistics

Prior to using statistical data, national agencies are often required to compile mappings to their own purpose-built frameworks or reconcile mappings between the different frameworks used by CWP parties and organizations. These prerequisite steps may be time consuming, costly and difficult to undertake if there is poor compatibility between concepts and definitions used by the agencies involved. However, the effort and cost of data harmonization may be greatly reduced by implementing a global standard framework for capture fishery and aquaculture statistics in order to foster the use by organizations of common definitions, standards and formats in their statistical dissemination systems. Where feasible this global standard may also facilitate the integration of data collection systems such as vessel registries, licensing of fishing activities or fishers, and logbook systems which are used for deriving statistics.

In this context, CWP has developed a global standard to facilitate the reporting and exchange of statistical data on capture fisheries and aquaculture for use by CWP parties and national, regional and international organizations. This standard, known as the CWP Standard for Reference Harmonization, establishes a framework for a modular set of data structures commonly used for data collection and reporting among CWP parties at different levels of the data value chain. The standard is based on statistical concepts, reference data and classifications agreed by CWP and published in the CWP Handbook. Harmonization of statistical concepts, including definitions and related metadata is an essential prerequisite for the interoperability and streamlining of information flow between data systems. The data structures use a set of common statistical concepts that represent minimum global requirements which accommodate the different coding systems used by CWP parties (Fig. 2).

Figure 2. Generalized pathway for data used in capture fishery and aquaculture statistics

The CWP Standard for Reference Harmonization may be used by agencies and organizations to facilitate the diverse requirements for reporting and exchanging national, regional and global statistical data on capture fisheries and aquaculture. Use of the standard is also expected to reduce the burden faced by national agencies when reporting to multiple organizations. The harmonized statistical concepts of the standard reduce the overall data and metadata reporting burden and associated cost, and lay the basis for establishing data exchange agreements among CWP parties. The standard also enhances the dissemination of comprehensive and harmonized statistics which are essential for the timely processing and analysis of data which underpins evidence-based advice on the sustainable development and management of capture fisheries and aquaculture. The CWP Standard for Reference Harmonization promotes the use of data modules to bring together statistical concepts relevant to each data structure (Fig. 3). CWP parties and organizations are encouraged to incorporate these data structures in their reporting functions and, where applicable, in their data collection frameworks.

The development of the CWP Standard for Reference Harmonization was initiated by CWP in 2015 (FAO, 2016). An ad-hoc Task Group on Reference Harmonization for capture fishery and aquaculture statistics was established to develop and test standard data structures to facilitate the interoperability across different organizations’ databases and simplify automation of data and metadata exchange (FAO, 2019a). A workshop dedicated to Tuna RFMOs (t-RFMOs) and CWP parties piloted the development of data structures with a focus on catch and effort statistics (FAO, 2019b). The workshop trialed the use of data structures to prepare published t-RFMO datasets of nominal catch and catch and effort for eventual dissemination in the FIRMS Global Tuna Atlas.

CWP has also emphasized the need to foster the use of a common set of reference data standards and international classifications to be exchanged together with the statistical datasets to enable the interpretation and interoperability of statistics across different organizations’ databases. While the emphasis was directed at the use of statistics at the global level, the outcomes of this work are also suitable for use at regional and national levels.

CWP endorsed the Standard for Reference Harmonization for initial use with data structures which underpin capture fishery statistics. CWP also endorsed implementation guidelines for the standard. Further work is underway to expand the set of data structures and associated definitions, concepts and classifications in order to support the full range of capture fishery and aquaculture statistics used by CWP parties and organizations.

Figure 3. CWP data structures and modules

FAO. 2016. Report of the twenty-fifth session of the Coordinating Working Party on Fishery Statistics. Rome, Italy, 23–26 February 2016. FAO Fisheries and Aquaculture Report No. 1172. Rome, FAO. 32 pp. (also available at

FAO. 2019a. Report of the twenty-sixth session of the Coordinating Working Party on Fishery Statistics. Rome, Italy, 15–18 May 2019. FAO Fisheries and Aquaculture Report No. 1293. Rome, FAO. 51 pp. (also available at

FAO. 2019b. FAO technical workshop on global harmonization of Tuna fisheries statistics. Rome, 19-22 March 2018. FAO Fisheries and Aquaculture Report No. 1239. Rome, FAO. 55 pp. (also available at

FAO. 2019c. Technical background document of the Task Group on Reference Harmonization. Twenty-sixth session of the Coordinating Working Party on Fishery Statistics. Meeting document. [Cited 1 November 2020].

FAO. 2022. Report of the twenty-seventh session of the Coordinating Working Party on Fishery Statistics. Rome, Italy, 20-24 June 2022. FAO Fisheries and Aquaculture Report No. 1397. Rome, FAO. 51 pp. (also available at

Taconet, M., Kroodsma, D., & Fernandes, J.A. 2019. Global Atlas of AIS-based fishing activity - Challenges and opportunities. Rome, FAO. (also available at


Resources for reference harmonization

FAO. FIRMS Global Tuna Atlas (GTA). 2023. Fisheries and Aquaculture Division [online]. Rome. [Cited Monday, July 17th 2023].