Recruitment and growth of the gooseneck barnacle Pollicipes pollicipes (Gmelin, 1791) in the Cantabrian Coast (Northern Spain, Gulf of Biscay)

Recruitment and growth of the gooseneck barnacle Pollicipes pollicipes (Gmelin, 1791) are essential life history parameters needed for the monitoring and assessment of the fishery performance and establishment of sustainable management practices. Here, intra-annual variability in recruitment and growth of the gooseneck barnacle P. pollicipes was first investigated in the Cantabria region (N Spain, Gulf of Biscay). The recruitment index IR1 as the number cyprids with rostro carina length (RC)$<$1 mm was estimated at two different intertidal levels and along the stalk of adult barnacles. The relationship of recruitment with sea surface temperature (SST) associated to breeding and with significant wave height was explored. For growth, RC length of juveniles, pre-adults and adults was measured in aggregated individuals. Recruitment was weak, showing a peak in autumn at the low tidal zone. Its relationship with SST was unclear, possibly due to the low intensity of the recruitment pattern, and no correlation was found with wave height. The great majority of recruits attached to the lower part of the adult stalk. The mean growth rate was significantly higher for juveniles (0.72 mm month⁻¹) compared to adults (0.36 mm month⁻¹), with peak growth occurring in spring. Based on these findings, regional shellfishery management guidelines are proposed, and future research directions are outlined, considering the limitations of this study in terms of spatial replicability