This is followed by a larval stage during which larvae drift in sea water before they metamorphose into baby periwinkle. They then recolonise on the rocky shore and are found in the middle region of the shore between low and high tide. They are also found in rock pools where it is sheltered and the water is shallow. Although picking is uncontrolled at present, Dr Burnell is optimistic that the fishery can be managed effectively. The scientists in NUI Cork and NUI Galway are working with the wholesalers and pickers to understand the dynamics of the fishery, and to arrive at a mutually agreeable management plan for its sustainable exploitation.
Growth rates vary over time, with least growth occurring in winter as air and sea temperatures fall.
The edible periwinkle reaches a commercially viable size at 16 mm. It is estimated that up to 30 per cent of the winkle crop is discarded by the wholesalers as being undersized. There is a large market for the edible periwinkle on the continent, principally in France and Spain.