Age and Growth of Bluemouth Helicolenus dactylopterus (Delaroche, 1809) in the Northern Waters of Tunisia (Central Mediterranean)

Data on age and growth of the bluemouth Helicolenus dactylopterus (Delaroche, 1809) from the Southern central Mediterranean Sea are provided in this paper. Ages of bluemouth rockfish (Scorpaenidae) in the northern Tunisian waters were estimated by otolith readings and verified by marginal increment analysis. A total of 513 individuals were measured, weighed and their sex was determined. The fish total length (TL) range between 8 and 30.6 cm, which corresponded to individuals between 0 to 9 years old. The otoliths showed the typical teleost fish pattern with alternated opaque and hyaline rings. Marginal increment analysis of specimens suggested that a single annulus was formed each year. The Von Bertalanffy growth function was selected as the most adequate model to fit this species' growth. Parameters of the growth curve were L_∞ =37.17cm, K=0.142year^-1, t₀= -1.67years. The weight-length relationship (TW= 2.2092 x10^-5TL^2.870)described a negative allometric growth of the species. The growth parameters obtained from the age-length relationships showed higher differences between sexes.