Age, growth and mortality of Sciaena umbra (Sciaenidae) in the Gulf of Tunis
Inès Chater, Ahlem Romdhani-Dhahri, Jean-Louis Dufour, Kélig Mahé, Nadia Chakroun-Marzouk

The growth and mortality of the brown meagre, Sciaena umbra from the Gulf of Tunis, were investigated using a sample of 276 specimens, ranging from 15.3 to 49.2 cm total length and from 43 to 1565 g total weight. Specimens were collected from artisanal fisheries between October 2008 and September 2011. Otoliths were extracted, thin cross-sections were realized and radii were measured. The log-linear morphometric relationships between total length-total weight and total length-otolith radius were significant (p<0.05), showed positive allometry (b=3.15) and isometry (b=0.90), respectively. The marginal analysis suggested that only one growth increment was deposited per year. The maximum age of the brown meagre was 22 years for males and 31 years for females. The fit of the von Bertalanffy growth function was significantly different between sexes (p<0.05): TL=43.8 cm, k=0.145 y–1, t0=–4.88 y for males and TL=50.1 cm, k=0.105 y–1, t0=–5.71 y for females. The instantaneous total (Z) and natural (M) mortalities were estimated for each sex, resulting in an exploitation ratio (E=F/Z) of 0.43 for males and 0.46 for females.

Keywords: brown meagre; thin otoliths; growth; mortality; Gulf of Tunis; Mediterranean Sea
Contents of this volume Sci. Mar. 82(1) : 17-25 Back PDF
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