Age and growth of the bastard grunt (Pomadasys incisus : Haemulidae) inhabiting the Canarian archipelago, Northwest Africa

Abstract

The bastard grunt (Pomadasys incisus) is one of the most abundant coastal demersal fishes inhabiting the Canary Islands. Age and growth were studied from samples collected between October 2000 and September 2001. Growth analysis revealed that this species is a fast growing and moderately short-lived species (ages up to seven years recorded). Length-at-age was described by the von Bertalanffy growth model (L-infinity=309.58 mm; k=0.220/year; t(0)=-1.865 year), the Schnute growth model (y(1)=126.66 mm; y(2)=293.50 mm; a=-0.426; b=5.963), and the seasonalized von Bertalanffy growth model (L-infinity=309.93 mm; k=0.218/year; t(0)=-1.896 year; C=0.555; t(s)=0.652). Individuals grow quickly in their first year, attaining approximately 60% of their maximum length; after the first year, their growth rate drops rapidly as energy is probably diverted to reproduction. The parameters of the von Bertalanffy weight growth curve were W-infinity=788.22 mm; k=0.1567/year; t(0)=-1.984 year. Fish total length and otolith radius were closely correlated, r(2)=0.912. A power relationship was estimated between the total length and the otolith radius (a=49.93; v=0.851). A year's growth was represented by an opaque and hyaline (translucent) zone-an annulus. Backcalculated lengths were similar to those predicted by the growth models. Growth parameters estimated from the backcalculated sizes at age were L-infinity=315.23 mm; k=0.217/year; and t(0)=-1.73 year.