Description

Age information is an essential component in growth rate, mortality rate and productivity calculations, hence it is classified among the most influential of biological variables. In the case of bony fishes, age determination methods based on annual growth marks are reasonably well established and are constantly applied. However, age determination methods in elasmobranchs have lagged behind those applied to teleosts. In this manual, the most recognized age determination methods for elasmobranchs have been brought together so as to provide a detailed and hands-on guide to successful and validated methods for ageing sharks, skates and rays. Particular emphasis is given to vertebral sections and image analysis techniques as applied to elasmobranch species from the Mediterranean Sea, suited to both novice and experienced age readers.