This study was undertaken using data drawn from 5 sites along the Atlantic shoreline of Galicia (Northwest Spain) for a period of 2 y. The length—weight relationship of Pollicipes pollicipes (Gmelin, 1789) was estimated to observe the way in which individuals of this species gain weight as they increase in size. A classic allometric model was used for the purpose. As an alternative, a more general nonparametric model was also estimated, using local linear kernel smoothers. Comparison of these two models showed that use of the nonparametric model resulted in a better fit of the data. In addition, derivatives were used for estimating a size of capture for this species. For the same purpose, we also estimated this crustacean's mean size at sexual maturation (L₅₀) and the number of broods that it spawns per annum. Individuals' weight gain, a female maturity size of 15.7 mm, and P. pollicipes' estimated 1.73 broods per annum tend to suggest a size of capture based on a rostrocarinal length of 21.50 mm.