Age and growth of bluemouth, Helicolenus dactylopterus, from the Portuguese continental slope

Sequeira, V., Neves, A., Vieira, A. R., Figueiredo, I., and Gordo, L. S. 2009. Age and growth of bluemouth, Helicolenus dactylopterus, from the Portuguese continental slope. – ICES Journal of Marine Science, 66: 524–531. In all, 933 bluemouth (Helicolenus dactylopterus) were obtained from bottom-trawl research surveys along the Portuguese continental slope between October 2005 and February 2007 and from commercial landings. Age was determined by reading whole sagittal otoliths, and age estimates were validated by daily growth increment (DGI) analysis. Fish ranged from 5.2 to 44.9 cm, which corresponded to fish between 0 and 30 years old. The mean total length obtained from DGI analysis for age class 1 fish was 8.6 cm, corresponding to otoliths with a mean radius of 1.8 mm. As no statistical differences between sex were observed, the von Bertalanffy growth equation fitted was Lt = 45.50[1 − e−0.05(t+4.01)]. Comparisons with other studies using Hotelling's T2 test and the growth perform index (Ф) are drawn. The growth rates estimated in this study using whole otolith readings were the lowest of all the studies available, and the estimated L∞ is lower then those obtained for Azorean waters and higher than those published for the Mediterranean.