Determination of Growth parameters of Chloroscombrus chrysurus (Linnaeus, 1766) from Length-frequency analysis in the Saloum Delta (Senegal)

Résumé

Abstract

It is important to know the biological parameters of the commercially exploited species for an efficient management of fishery. The aim of this study is to estimate the growth parameters of Chloroscombrus chrysurus (Linneaus, 1766) using length-frequency data in ELEFAN system. From September 2014 to December 2015, biological aspects of C. chrysurus were examined out of a total of 352 specimens collected from the Saloum Delta (Senegal). The growth parameters were estimated using length-frequency analysis. The length-weight relationship and the von Bertalanffy equation were used to evaluate the fish growth. The total length (TL, cm) of the captured fishes ranged from 10 to 25 cm with an average of 17.5 ± 1.03 cm. The length-weight relationship shown a positive allometric growth (b = 3.11) in marine population and a negative allometric growth (b = 2.87) in estuarine population. The relationship linking the total length to the fork length showed a slope greater than 1 and a strong correlation (r² = 0.99). The estimated growth parameters were: L_∞= 29.6 cm, k = 0.20, t₀= -0084, Φ’ = 2.25 in marine and L_∞= 23.2 cm, k = 0.18, t₀ = -0.86, Φ' = 2.23 in estuary. With regards to condition factor (K), there was a decreasing trend over the hot period (wet season) probably corresponding to the seasonal reproductive activity. The C. chrysurus grew rapidly during the first two years of its life and then growth slows down. The growth coefficient (k) showed a slow attainment of maximum size.

Keywords: Chloroscombrus chrysurus, length-weight relationship, condition factor, growth parameters.