This publication is part of the Studies and Reviews series of the General Fisheries Commission for the Mediterranean (GFCM), which focuses on specific aspects of scientific interest for Mediterranean and Black Seafisheries. This handbook is the fruit of the coordinated work by 23 researchers from different institutes and stems from an experience on fish ageing analysis carried out at the Mediterranean level. It falls within one of the main targets of the mid-term strategy (2017–2020) towards the sustainability of Mediterranean and Black Sea fisheries implemented by the GFCM, which aims, among other things, to enhance knowledge and expertise on fisheries namely by strengthening data collection and information. Since 1984, several institutes in Italy have been involved in national and international scientific programmes on fisheries, focused on the study of the biology, ecology, population dynamics and assessment of the most important fishery resources, such as Merluccius merluccius, Mullus barbatus, Sardina pilchardus and Engraulis encrasicolus. In accordance with regulations, (including within the GFCM Data Collection Reference Framework [DCRF] and, at the European level, the Data Collection Framework [DCF]), biological, environmental, technical and socio- economic data have been regularly collected for the fishing and processing sectors. Since the beginning of data collection, the need for coordination was present and there was general agreement that regional coordination would greatly increase the efficiency of national programmes. In light of this, a working group on fish ageing analysis was created in 2014 under the supervision of the Italian Society of Marine Biology (SIBM). The present volume reports the main results of this working group. This document was produced with the financial support of the European Union. The views expressed herein can in no way be taken to reflect the official opinion of the European Union.