Handbook on fish age determination

This Handbook stems from an experience on fish ageing analysis carried out at the Mediterranean level. It aims to provide guidelines to standardize the current methods used in fish ageing studies and it gives an overview of the general principles on which age analysis relies (assignment of birth date, preparation methods, aging scheme reading and identification of true and false rings). The volume provides information on extraction and storage, preparation methods, age interpretation and ageing criteria by species, analysing a total of 30 species. As such, it represents one of the most complete outlooks on fish ageing analysis in the Mediterranean context. Fish age, among other biological parameters, is one of the most relevant pieces of data in reaching sustainable exploitation of fisheries resources. Indeed, most analytical methods used in stock assessment require knowledge of demographic structure according to the 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 literature on ageing analysis shows some gaps regarding ageing schemes, criteria and methodologies used in preparing calcified structures. These aspects affect both the precision and accuracy of age estimation. One action that could be taken to overcome this gap was to formalise a handbook that clarified approaches to ageing schemes, criteria and preparation methods. Having a common protocol is indeed fundamental to decreasing bias associated with the activities of age determination and to improving precision in age reading