This handbook presents a summary of the age estimation procedures used in Spanish Institute of Oceanography (IEO) for some of the main commercial small and medium pelagic species of the Spanish fleet: anchovy (Engraulis encrasicolus), sardine (Sardina pichardus), mackerel (Scomber scombrus), chuck mackerel (Scomber colias), horse mackerel (Trachurus trachurus), Mediterranean horse mackerel (Trachurus mediterraneus) and blue whiting (Micromesistius poutassou). It provides information about the sampling program, otolith extraction and preparation, and the age estimation criteria. A summary of the information related to the age accuracy, validation and corroboration of each species is also presented, as well as that related to the age precision, quality control and verification
