These guidelines are intended to help those who design routine data collection programmes, focusing on the relationship between typical questions asked by policy-makers and managers, and the data required for providing reliable answers. Fisheries policy and management objectives, particularly under the precautionary approach, need to be based on analyses of reliable data. Data are needed to make rational decisions, evaluate the fisheries performance in relation to management activities and fulfil regional requirements. These objectives are achieved using fishery performance indicators. Indicators are used to measure the state of the resource, the performance of fishing controls, economic efficiency, socio-economic performance and social continuity. The primary factor in choosing which data to collect is the link between the necessary operational, biological, economic and socio-cultural indicators and their associated variables. The way in which different data variables are collected needs to be tailored to the structure of the fishery. The strategy will be strongly influenced by the budget and personnel available, and the degree to which fishers and others cooperate. The programme must identify which variables should be collected through complete enumeration and which can be sampled. Collection methods are influenced by the variable itself, the strategy, collection point and the skill of the enumerator. Once collected, fishery data must be stored securely but made easily available for analysis, which is achieved through a computer-based data management system, following the basic data processing principles. The implementation of a data collection programme should follow a normal project cycle, developing a new legal and institutional framework as appropriate.