The tub gurnard Chelidonichthys lucerna has been identified by ICES as a potential commercial species in the northeast Atlantic with recommendations made to monitor landings and discards and to derive information on population biology for stock assessment purposes, however, data are lacking for the species in the northeast Atlantic. Therefore, aims of this study were to provide data on the size/age-structure and patterns of growth, maturity and mortality of C. lucerna in Northwest Wales, UK, and in doing so to provide data on the biological characteristics of the most northerly population studied to date for comparison with the existing data for southerly Mediterranean populations. Data on the age, growth and maturity of C. lucerna were collected by otter trawling (73 mm cod-end stretched mesh size) in the coastal waters of Northwest Wales, UK in October (2000-2011, excluding 2006). Total length (TL) of fish sampled ranged between 10.5-41.0 cm (males) and 10.4-57.5 cm (females). The majority of the female fish were between 20-30cm TL (60.2%) and the majority of the male fish between 20-30cm TL (58.3%) respectively. TL/weight (W) relations for male and female fish were similar and the combined data was described by W = 0.0067 TL3.10. Age of fish ranged between 1-7 years old for female fish and 1-5 years old for male fish respectively with the majority of female fish 3 years old (40%) and the majority of male fish 3 years old (37%). The age structures of female and male tub gurnards were not significantly different with the older age classes consisting predominantly of female fish. Both males and females exhibited similar asymptotic growth patterns and the combined von Bertalanffy growth function was TLt = 51.6 (1- e [-0.25(t + 0.41)]). Instantaneous rates of total mortality were calculated as 1.04 year-1 for males and 1.11 year-1 for females. The size (L50) and age at first maturity (A50) were estimated to be 29.1 cm TL and 2.8 years for males, 27.7 cm TL and 2.7 years for females and 28.0 cm TL and 2.8 years for both sexes combined. The results of this study provide the first information on the biology and population dynamics of C. lucerna in the Irish Sea, the first data collected in the northeast Atlantic since 1985 and the most northerly population studied to date.