Some Growth Traits of the Atlantic Lizardfish Synodus Saurus in The Southern Mediterranean Sea

Abstract

Abstract: This study aimed to determine the growth traits of the Atlantic lizardfish (Synodus saurus) in the Southern Mediterranean Sea (Benghazi, eastem Libya). The von Bertalanffy growth model parameters were derived from length-at-age data obtained by reading growth annuli on scales (Sc) from a sample of 70 fish, from the length-frequency-distribution (LFD) of a random sample of 600 fish, and by the Solver statistics (So). In both Sc and LFD methods, the constants L and k, and to were estimated using the Walford, and the von Bertalanffy methods, respectively. Total mortality (Z) was calculated using the linearized catch curve, natural mortality (M) was estimated using Pauly's empirical formula, and the fishing mortality (F) was determined by subtraction. The mean total length (TL) of the fish was 20.14 cm, with a corresponding mean weight (TW) of 66.93 gm. The ratio of head length to total length was 0.223. The von Bertalanffy constants, as calculated from Sc, LFD, and So methods, respectively, were L: 46.99, 45.03, 48.23 cm; k: 0.094, 0.1105, 0.092 year1; to: -2.5944, -1. 697, -2.7101 year. The growth performance index (0/) values were 2.317, 2.350, 2.330, respectively. The growth models derived from these methods (Sc, LFD, So) showed high reliability, the lengths-at-age predicted were close to the observed values. The residuals of the three methods were analyzed and compared. In addition to TL, TW, and head length-to-TL ratio, key fisheries-related parameters included total mortality (Z) "0.7286 year", fishing mortality (F) "0.368 year 1" and the survival rate (5) "0.4826" calculated from LFD, and the following parameters calculated from Sc, LFD, So, consecutively: natural mortality (M): 0.3208, 0.3609, 0.314 year1; Length-at first maturity (Lm): 12.23, 11.78, 12.51 cm; Length at optimum yield (Lopt): 21.98, 21.56, 22.82 cm. The exploitation ratio