Volumen 43 - Número 3: 521-529 | 2008
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Morphometry, age and growth of Siganus luridus Rüppell, 1828 and Siganus rivulatus Forsskål, 1775 (Siganidae) in the central Mediterranean (Libyan coast)

Esmaile Shakman^1*, Helmut Winkler¹, Rainer Oeberst² and Ragnar Kinzelbach¹ 

¹General and Systematic Zoology, Universitätsplatz 2, D-18055 Rostock University, Germany
²Institute for Baltic Sea Fisheries, Alter Hafen Süd 2, D-18069 Rostock, Germany

*This email address is being protected from spambots. You need JavaScript enabled to view it.

Some biological aspects of two siganid fish species from the Libyan coast were studied in terms of morphometry, age and growth. Two species were collected, between March 2005 and March 2006, comprising of 1,672 individuals of S. rivulatus from the eastern coastline and 1,756 individuals of S. luridus from the western coast and the Gulf of Sirt. The age of each species was estimated based on otoliths analysis and the results were discussed with data available from different areas of the Mediterranean and Red Seas. The age of S. rivulatus ranged from one to six years and S. luridus from one to seven years. The relationships between different morphometric measurements and total lengths for both species were positively correlated. Von Bertalanffy growth functions were estimated with L_T = 35 (1 – e ^{-0.160 (t + 1.04)}) and L_T = 30 (1 – e^{-0.213 (t + 0.784)}) for S. rivulatus and S. luridus respectively. The von Bertalanffy growth curves suggest faster growth rates for S. rivulatus. The length-weight relationships were WT = 0.233 L_T ^2.82 (S. rivulatus) and WT = 0.101 L_T ^3.23 (S. luridus). S. luridus would increase in weight at a more rapid rate than S. rivulatus, and this may point to a lake of suitable food supply for the S. rivulatus individuals in this region.

Key words: Biology, morphometry, age, siganids, Libya