Age and growth of two deep-water fish species in the Azores Archipelago: Mora moro (Risso, 1810) and Epigonus telescopus (Risso, 1810)

Abstract

Age and growth of Mora moro and Epigonus telescopus were studied using 634 and 232 otoliths, respectively, from specimens caught in the Azores between 1999 and 2009. Otoliths of both species were sectioned through the nucleus, a preparation method that improved the age assignment. Marginal increment analysis showed that, for both species, growth increments (consisting of as single set of translucent and opaque growth increments) were formed annually. M. moro specimens ranged from 22 to 76cm fork length, were aged from 8 to 59 years, and showed a sexual dimorphism in growth. E. telescopus specimens ranged from 32 to 70cm fork length which corresponds to ages between 12 and 39 years. No differences in growth between sexes were observed. Growth behaviour of M. moro was better explained by the three parameter von Bertalanffy model. The five parameter model provided a better fit to the E. telescopus data. Under this model a change in growth at 26 years for females and 25 years for males may be related to the onset of sexual reproduction.