Age and growth of Pontinus kuhlii (Bowdich, 1825) in the Canary Islands

Abstract

Pontinus kuhlii is a Scorpaenidae which forms part of the bottom longline by-catch in the Canary Islands fisheries within setting operations from 200 to 400 metres depth. Information on their biology and on the age determination and growth of the species is very scarce. The main objective of the study was to look at this biological aspect based on 421 specimens caught in the Canarian Archipelago during the period July 1996 and August 1997, 286 of which were male, 130 female and 5 indeterminate. Age was determined through the interpretation of annual growth rings of otoliths and scales, and the results fitted the von Bertalanffy growth function. Otolith sectionings were discarded due to annuli losses caused by the edge structure. The structures used in age interpretation showed numerous false rings that made the process difficult, causing 17% of the cases to be rejected. However, the age interpretations from scales showed less variability in relation to the whole otolith. The ages of the specimens ranged from 6 to 18 years for males and from 6 to 14 years for females. The growth parameters for males were: K= 0.132, L_? = 46.7 and t_o= 1.74; for females: K= 0.094, L_?= 46.3 and t_o= 0.05; and for the total: K= 0.095, L_?= 52.2 and t_o= 1.01.