Handbook on fish age determination: a Mediterranean experience

Book excerpt: This handbook provides guidance on methods for use in fish ageing studies. Fish age, among other biological parameters, is one of the most relevant pieces of data to attain sustainable exploitation levels of fishery resources. Indeed, most analytical methods used in stock assessment require knowledge of demographic structure according to age of stocks, as well as to recruitment, growth, maturity, natural mortality, etc., which are strictly linked to information on age and age structure. The handbook was put together to deal with identified gaps – which affect both the precision and the accuracy of estimations – regarding ageing schemes, criteria and methodologies used in preparing calcified structures. It focuses on the general principles that underpin age analysis (assignment of birth date, preparation methods, aging scheme reading and identification of true and false rings). Crucially, it aims to contribute to the establishment of common analysis methods, which can enable better calibration across the diverse institutes involved, thereby improving the quality and reliability of results.