First information on biology of the needlefish Tylosurus acus imperialis (Belonidae) off the Tunisian coast (Central Mediterranean)

Chaari M., Boudaya L., Gancitano S., Gancitano V., Fiorentino F., Neifar L.

Published date: December 2014
Volume: 38
Number: 4
Pagination: 273–278
Publisher: Société Française d'Ichtyologie
doi: https://doi.org/10.26028/cybium/2014-384-005
Abstract

Sex ratio, age and growth, length and age at sexual maturity, and spawning season of the Mediterranean needlefish Tylosurus acus imperialis (Rafinesque, 1810) off Tunisian coast were investigated. A total of 126 individuals (54 females and 72 males) were sampled. The length weight relationships for females and males were W = 0.0027 L2.832 (s.e.a ± 0.004; s.e.b ± 0.238) and W = 0.0026 L2.827 (s.e.a ± 0.002; s.e.b ± 0.188), respectively. Otolith reading revealed that females belonged to age groups from 0 to 6 years and males from 2 to 4 years. Most of individuals were of age groups 3. The parameters of the von Bertalanffy growth function were L∞=123.78 cm (s.e. ± 17.93), k = 0.2 year-1 (s.e. ± 0.07) and to = -2.28 year (s.e. ± 0.57) for females and L∞ = 92.28 cm (s.e. ± 5.93), k = 0.5 year-1 (s.e. ± 0.15) and to = -1.16 year (s.e. ± 0.45) for males. First sexual maturity was estimated at total length of 79.09 ± 0.71 cm for females and 79.18 ± 1.83 cm for males. Gonadosomatic index pattern indicated the spawning season extended from May to July.

Keywords: Belonidae - Central Mediterranean - Growth - Otolithometry - Reproductive biology - Tunisia - Tylosurus acus imperialis
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