Ten years of monitoring recruitment of the edible stalked barnacle Pollicipes pollicipes: linking to oceanographic variability

Abstract

Understanding recruitment patterns of an exploited species is essential to predict changes in population dynamics and to improve its management and conservation. Temporal variability in recruitment of the edible stalked barnacle Pollicipes pollicipes was analyzed over a decade (consecutive annual recruitment seasons from 2007 to 2016) at a cape area located in the Canary-Iberia Current Upwelling System (Cape of Sines, Southwestern Portugal), in terms of (1) the timing and length of the main recruitment season and (2) the variation in monthly and annual recruitment intensity and its relationship with several oceanographic variables. A longer recruitment season was detected, corresponding to approximately 9–10 months (June through either March or April of the following year, as in 2012, 2015, and 2016) in recent years, while a shorter recruitment season was detected between 2007 and 2010 (< 5 months, September–January in 2007 and July–December in 2010). Mean annual recruitment from 2012 to 2016 was about four times higher (ca. 43 recruits adult−1) than in the first 5 yr of the 10-yr period (ca. 12 recruits adult−1). Correlation analyses between monthly recruitment and oceanographic variables revealed a significant positive correlation with sea surface temperature and a negative correlation with upwelling index. Results indicate a trend toward a longer recruitment season and a higher recruitment intensity in recent years (2012–2016), and a clear association between recruitment of P. pollicipes and both relaxation of upwelling and seawater warming.