Le sex-ratio, l'âge et la croissance, la taille et l'âge à la maturité sexuelle et la saison de frai de la grande aiguille Tylosurus acus imperialis (Rafinesque, 1810), provenant des côtes tunisiennes, ont été étudiés. Un total de 126 individus (54 femelles et 72 mâles) a été examiné. Les relations taille-masse pour les femelles et les mâles sont W = 0,0027 L2,832 (e.s.a ± 0,004; e.s.b ± 0,238) et W = 0,0026 L2,827 (e.s.a ± 0,002 ; e.s.b ± 0,188), respectivement. La lecture des otolithes indique que les femelles appartiennent à des groupes d'âges compris entre 0 et 6 ans et les mâles entre 2 et 4 ans, la majorité des individus appartiennent au groupe d'âge 3 ans. Les paramètres de croissance de von Bertalanffy sont : L? = 123,78 cm (e.s. ± 17,93), k = 0,2 ans-1 (e.s. ± 0,07) et to = -2,28 ans (e.s. ± 0,57) pour les femelles et L? = 92,28 cm (e.s. ± 5,93), k = 0,5 ans-1 (e.s. ± 0,15) et to= -1,16 ans (e.s. ± 0,45) pour les mâles. La taille de première maturité sexuelle a été estimée à une longueur totale de 79,09 ± 0,71 cm pour les femelles et de 79,18 ± 1,83 cm pour les mâles. Le suivi de l'indice gonadosomatique montre que la saison de reproduction s'étend de mai à juillet.
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 L-2.832 (S.e.(a) +/- 0.004; s.e(.b) +/- 0.238) and W = 0.0026 L-2.827 (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 infinity=123.78 cm (s.e. +/- 17.93), k = 0.2 year(-1) (s.e. +/- 0.07) and t(0)= -2.28 year (s.e. +/- 0.57) for females and L infinity= 92.28 cm (s.e. +/- 5.93), k = 0.5 year(-1) (s.e. +/- 0.15) and t(0)= -1.16 year (s.e. +/- 0.45) for males. First sexual maturity was estimated at total length of 79.0 +/- 90.71 cm for females and 79.18 +/- 1.83 cm for males. Gonado-somatic index pattern indicated the spawning season extended from May to July.
First information on biology of the needlefish Tylosurus acus imperialis (Belonidae) off the Tunisian coast (Central Mediterranean)
Gancitano Salvatore;Gancitano Vita;Fiorentino Fabio;
2014
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 L-2.832 (S.e.(a) +/- 0.004; s.e(.b) +/- 0.238) and W = 0.0026 L-2.827 (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 infinity=123.78 cm (s.e. +/- 17.93), k = 0.2 year(-1) (s.e. +/- 0.07) and t(0)= -2.28 year (s.e. +/- 0.57) for females and L infinity= 92.28 cm (s.e. +/- 5.93), k = 0.5 year(-1) (s.e. +/- 0.15) and t(0)= -1.16 year (s.e. +/- 0.45) for males. First sexual maturity was estimated at total length of 79.0 +/- 90.71 cm for females and 79.18 +/- 1.83 cm for males. Gonado-somatic index pattern indicated the spawning season extended from May to July.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
