The sustainability within the fisheries of the commercially important European whelk, Buccinum undatum, has become a major concern through over-exploitation and increased landings in many European coastal shelf seas due to the expansion of export markets to East Asian countries. Current management of B. undatum populations is difficult to achieve as several life history traits make them problematic to accurately monitor. The current method of age determination for stock assessment has a low success rate and focuses on the use of putative annual rings on the surface of the organic operculum. Here we validate an annual periodicity of growth ring formation in B. undatum statoliths that provides an alternative, reliable and accurate method for determining a whelk’s age. Laboratory reared juvenile B. undatum of known provenance and age deposited a hatching ring at the time of emergence from their egg capsule and a clearly defined growth ring during February of their first and second years. Stable oxygen isotope profiles around the shells of two adult whelks confirmed annual growth ring deposition by demonstrating seasonal cycles of δ18O in the shell that matched the relative position and number of visible growth rings in the statolith. Validation of annually-resolved statolith growth rings will for the first time, provide fisheries scientists with a tool to determine the age structure of B. undatum populations and allow analytical stock assessments that will enable informed decisions for future management practices of whelk fisheries.