Life history parameters, including size-age, production, mortality and size at reproductive maturity, were studied on the edible snail Adelomelon ancilla to provide useful management data. Stable oxygen isotope ratios confirmed semiannual formation of internal growth marks. Adelomelon ancilla can reach up to 18 years at a size of 150 mm, fitting to a Gompertz growth model. Size at which 50% of the population matured was 73.5 mm in males (7 years) and 93.5 mm in females (9 years). The long lifespan of this species is comparable to other large gastropods, in particular volutids from southern Atlantic Ocean. Longevity, low somatic production, low population density, late reproductive maturity and direct development with few embryos, makes A. ancilla a vulnerable resource that will require a proper management approach incorporating estimates of these life history parameters.