(Re-)Examining age and growth increments of the clam Venus verrucosa

Abstract

Warty venus Venus verrucosa is a commercially important bivalve species that is widely distributed in the Mediterranean Sea. Understanding the main biological characteristics of exploited species, including their age and growth dynamics, are crucial for fisheries assessment, monitoring programmes and sustainable resource management. In this study, we analysed the age of the largest V. verrucosa specimens collected in Pag Bay, eastern Adriatic Sea, to investigate the maximal lifespan of this species. We used images of acetate peel replicas of the shell hinge region to visualize and count the growth increments. Radiocarbon content (14C) of selected shell material was analysed to corroborate the long lifespan derived from counting the growth lines in acetate peel replicas of etched shell sections. The maximum estimated lifespan of the analysed V. verrucosa specimens was 29 years, which is more than a decade longer than previously known. Pronounced variations in growth rates were noted among specimens of similar size, clearly indicating that shell size is not a reliable indicator of age for this species. Therefore, caution is advised when using the size-frequency distribution of the population to interpret the age structure of V. verrucosa.