Age and growth of the red flounder Paralichthys orbignyanus (Teleostei: Pleuronectiformes) in southern Brazil

Abstract

The red flounder Paralichthys orbignyanus is a large pleuronectiform fish endemic in coastal waters, coastal lagoons and estuaries in the southwestern Atlantic. Although less abundant than other Paralichthys spp., its high price makes it a valuable resource for small-scale fishers that have been intensely fished in the last decades. To study its growth and lifespan in southern Brazil, we examined thin otolith sections collected for age determinations of both young-of-the-year (YOY) and older fishes. Opaque bands form mainly in spring and summer, coincident with the reproductive season. Larger and older males reached 601 mm and eight years, while females reached 985 mm and 11 years. The assumed daily microincrements counts ranged from 127 to 196 for YOY of 135 to 184 mm TL. The common weight-length equation for grouped sexes was TW_♀♂ = 0.000015TL^2.93 (mm, g). The von Bertalanffy growth equations were: TL_♀ = 1,076(1–e^{–0.15 (t+0.78)}); TL_♂ = 652(1–e^{–0.28 (t+0.48)}); and TL_♀♂ = 839(1–e^{–0.20 (t+0.67)}). Therefore, P. orbignyanus is a fast-growing and relatively short-living species for which females attain larger length and older ages than males, characteristics that have to be taken into account for its stock assessment and management.