Studies on age determination and growth pattern of the wedge sole Dicologoglossa cuneata (Moreau, 1881) in the Spanish waters of the Gulf of Cadiz (southwest Iberian Peninsula)

Abstract

ABSTRACT The wedge sole Dicologoglossa cuneata (Moreau, 1881) is a typical coastal soleid which is considered as one of the main target species in the demersal fishery of Spain fs southern Atlantic region. This paper presents a study on the growth pattern of wedge sole in the Gulf of Cadiz. Age was determined by observing and analysing whole otoliths (sagittae), thereby obtaining the mean lengths at age for males and females in the year 1993 (from 15-20.9 cm TL and 1-4 years for males; from 15.9-23.6 cm TL and 1-6 years for females). In addition, the growth parameters for both sexes were obtained according to the Von Bertalanffy equation: L ‡ = 24 cm, K = 0.343 and t0 = .1.384 for males; L ‡ = 27 cm, K = 0.296 and t0 = .1.520 for females (showing growth differences growth between the sexes). These were compared with results reported by other authors for other areas of the species fs distribution range. Through the interpretation of the otolith and its edge, a sequence of annual rapid- and slow-growth rings was observed; otoliths with an opaque edge (rapid growth) showed the highest percentages in the period from May to October. Mean otolith diameters for each of the estimated ages were calculated, as well as the body length/otolith diameter relationship: a = .12.631 and b = 61.033 (r2 = 0.70).

RESUMEN La acedia Dicologoglossa cuneata (Moreau, 1881) es un soleido tipicamente costero, considerado como una de las especies objetivo de las pesquerias demersales de la region suratlantica iberica. En este trabajo se estudia el patron de crecimiento de la acedia del golfo de Cadiz. La determinacion de la edad se realizo mediante la lectura de otolitos enteros (sagitta), obteniendose las tallas medias por clase de edad para machos y hembras del ano 1993 (entre 15 y 20,9 cm de longitud total y de 1 a 4 anos para machos; de 15,9 a 23,6 cm de longitud total y de 1 a 6 anos para hembras). Por otra parte, se estimaron los parametros de crecimiento para ambos sexos segun la ecuacion de Von Bertalanffy: L ‡ = 24 cm, K = 0,343 y t0 = .1,384 para machos; L ‡ = 27 cm, K = 0,296 y t0 = .1,520 para hembras, presentando ambos sexos un crecimiento diferente. Estos resultados se compararon con los obtenidos por otros autores en otras areas del rango de distribucion de la especie. Mediante la interpretacion del otolito y su borde, se observa una sucesion anual de anillos de crecimiento lento, formados durante el periodo invernal, y otros de crecimiento rapido, que muestran los porcentajes mas altos en el periodo de mayo a octubre. Se calcularon los diametrosn