Validation of age determination methods and growth studies of the sand sole Pegusa lascaris (Soleidae) from the eastern-central Atlantic

Jg Pajuelo,Jm Lorenzo

doi:10.7773/cm.v37i3.1826

Abstract

The age and growth of the sand sole Pegusa lascaris from the Canarian Archipelago were studied from 2107 fish collected between January 2005 and December 2007. To find an appropriate method for age determination, sagittal otoliths were observed by surface-reading and frontal section and the results were compared. The two methods did not differ significantly in estimated age but the surface-reading method is superior in terms of cost and time efficiency. The sand sole has a moderate life span, with ages up to 10 years recorded. Individuals grow quickly in their first two years, attaining approximately 48% of their maximum standard length; after the second year, their growth rate drops rapidly as energy is diverted to reproduction. Males and females show dimorphism in growth, with females reaching a slightly greater length and age than males. Von Bertalanffy, seasonalized von Bertalanfy, Gompertz, and Schnute growth models were fitted to length-at-age data. Akaike weights for the seasonalized von Bertalanffy growth model indicated that the probability of choosing the correct model from the group of models used was >0.999 for males and females. The seasonalized von Bertalanffy growth parameters estimated were: L∞ = 309 mm standard length, k = 0.166 yr–1, t0 = –1.88 yr, C = 0.347, and ts = 0.578 for males; and L∞ = 318 mm standard length, k = 0.164 yr–1, t0 = –1.653 yr, C = 0.820, and ts = 0.691 for females. Fish standard length and otolith radius are closely correlated (R2 = 0.902). The relation between standard length and otolith radius is described by a power function (α = 85.11, v = 0.906).

Highlights

Flatfishes are among the most valuable fishes used for consumption and support fisheries throughout the world
One mode was observed during a 12-month period and, it was assumed that each translucent ring represented an annulus, with one year’s growth represented by an opaque ring and its adjacent translucent one
In the case of P. lascaris, the narrowness of the otoliths allowed us to carry out a correct reading of age without the need for sectioning

Summary

Introduction

Flatfishes are among the most valuable fishes used for consumption and support fisheries throughout the world. De alto valor comercial, son utilizados para el mejoramiento de las poblaciones o en cultivos intensivos (Howell y Yamashita 2005). The sand sole Pegusa lascaris (Risso 1810) is the species of the genus with the widest geographical distribution, from the central part of the North Sea to South Africa, around the Canary Islands, and in the Mediterranean, Black, and Azov seas (Quéro et al 1986). This species has a growing commercial interest. In Portugal, its landings have quadrupled in the last decade from about 28 t in 1990 to 116 t in 2000 (Teixeira et al 2009), and in the Canarian Archipelago, P. lascaris and Microchirus azevia (Risso 1810) are the most abundant, making up around 95% of the total landings of flatfishes (Pajuelo and Lorenzo 2008)

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