ABSTRACT. – Bluemouth, Helicolenus dactylopterus, is a zygoparous species with internal fertilization that stores the spermatozoa in crypts within the female ovaries and then releases embryos in initial development stages enclosed in a gelatinous matrix. It is a batch spawner species but the type of fecundity is unclear. This issue is investigated based on four criteria: (a) oocyte size frequency distribution, (b) the number of cortical alveoli and vitellogenic oocytes in the ovary, (c) the mean diameter of the advanced vitellogenic oocytes, and (d) atresia, over the spawning season. To estimate the changes in size and number of yolked oocytes during the spawning season, a stereological method was applied. Atresia was analysed based on the incidence of α-atresia stage in yolked oocytes. The results showed that (i) there is no distinct hiatus between cortical alveoli and vitellogenic oocytes, (ii) the number of cortical alveoli and vitellogenic oocytes, and (iii) the mean diameter of the advanced vitellogenic oocytes, stay constant during the spawning season, (iv) a high intensity of atresia was found at the end of the spawning season. These results indicate that bluemouth has most probably an indeterminate fecundity.