On the age and growth of flounder Paralichthys orbignyanus (Jenyns, 1842) in Bahía Blanca Estuary, Argentina

Abstract

Estimates of age and growth of flounder Paralichthys orbignyanus (Jenyns,1842) were made by analysing fish from commercial catches in Bahı´a Blanca estuary (39°LS). A total of 823 fish caught by fishing fleets operating in the estuary were collected between February 1997 and January 1998. Age was determined via scale reading and growth estimation parameters using von Bertalanffy's equation. Annulus formation occurred in August. The age for the total population, which ranged from 7.7 to 87.5 cm TL was 0-7. Age ranged from 0 to 6 years (21.5-71.9 cm TL) in males and from 0 to 7 years (24.9-87.5 cm TL) in females. Length-weight relationships were W(g) ¼ 0.0093 L(cm) exp. 3.03 for the total population, W(g) ¼ 0.0147 L(cm) exp. 2.91 for females, and W(g) ¼ 0.0168 L(cm) exp. 2.87 for males, respectively. As from age three, females were longer and heavier than males. The growth parameters estimated for the total population, for females and for males were L¥ ¼ 83.29, 79.66, and 46.11 cm, respectively; k values were 0.18, 0.23, and 0.92, respectively, and t 0 values were )1.87; )1.54, and )0.62, respectively. Similarly to other flounders, P. orbignyanus is a typical inhabitant of estuaries and coastal regions. Adults stay in the study area mainly during spring and summer, they go outside or offshore during the spawning period and then they return to the estuary for feeding and recovering.

Some biological parameters of Jenyns' sprat Ramnogaster arcuata (Pisces: Clupeidae) in south-western Atlantic waters

“…Paralichthys orbignyanus (Paralichthyidae), in which only one increment per year was detected on their otoliths and scales, respectively (Lopez Cazorla, 2000Cazorla, , 2005. Estimates of growth parameters for Jenyns' sprat suggest that this fish is a relatively fast growing species.…”

Gonadal Sex Differentiation in Cultured Juvenile Flounder, Paralichthys orbignyanus (Valenciennes, 1839)

“…It is known that wild adult female as well as cultured juvenile female P. orbignyanus grow faster and larger than males (López Cazorla 2005; López et al 2006). Hence, methods to control sex with the final purpose of culturing monosex populations of only faster growing females have become an important issue for the optimization of future commercial production.…”

Sobrevivência E Crescimento De Juvenis Do Linguado Paralichthys Orbignyanus Criados Em Diferentes Temperaturas

“…Esta heterogeneidade pode estar parcialmente ligada ao sexo, já que estudos em populações selvagens demonstram que fêmeas de P. orbignyanus crescem mais rápido que machos (Cazorla 2005). Por tanto, a produção monossexo de fêmeas poderia ser um meio de corrigir este problema e otimizar a produção de linguado.…”