Age of black dogfish ( Centroscyllium fabricii ) estimated from fin spines growth bands and eye lens bomb radiocarbon dating

Accurate age estimates are key life history parameters for understanding growth, reproduction and susceptibility to exploitation. Using a combination of fin spine growth increments and bomb radiocarbon dating, we provide minimum age estimates for the small Atlantic squaloid shark, black dogfish ( Centroscyllium fabricii ) sampled in Greenland waters. Age estimates based on growth increments in the fin spine, just distal to the end of the pulp cavity, were obtained from males ( N = 64) and females ( N = 70), and von Bertalanffy growth curves were fitted. The maximum growth increment count was 36 in males and 35 in females. Males and females had similar growth rates, but females grew larger ( L inf, females = 68 cm, L inf, males = 61 cm). To evaluate the fin spine age estimates, bomb radiocarbon dating on eye lenses were done on a selection of females. All individuals larger than 65 cm (total length) were older than the bomb pulse corresponding to an age of at least 53 years, while those smaller than 55 cm were younger. Therefore, we observe a discrepancy between age estimates obtained from fin spines and bomb radiocarbon dating, indicating that fin spines are unsuitable for ageing black dogfish, at least for the oldest individuals.