Starost i rast glavoča travaša Zosterisessor ophiocephalus Pallas, 1811 u zaljevu Gabes (Tunis, središnji Mediteran)

Abstract

Zosterisessor ophiocephalus is currently an important component of the eastern Mediterranean inshore fisheries. In Tunisia it was recorded for the first time in the Gulf of Gabes in 1993, where it is now an important fished species. In this study age and growth parameters were determined in the Gulf of Gabes (southeast of Tunisia) based on otolith analysis of 824 specimens caught between September 2006 and August 2007. Monthly changes in marginal increments, determined from alternation of macroscopic opaque and translucent bands, of Zosterisessor ophiocephalus sagittae were examined. These results allowed us the estimation of the approximate age to the appearance of each annulus. The observed age was 6 years old for both sexes. Von Bertalanffy parameters based on length at age data were TL∞ = 24.83 ± 1.69 cm, K = 0.19 ± 0.03 year-1 and t0 = - 0.91 ± 0.12 for males and TL∞ = 24.13 ± 1.17 cm, K = 0.20 ± 0.02 year-1 and t0 = - 0.80 ± 0.09 for females. The length-weight relationship for both sexes of Zosterisessor ophiocephalus is Wt = 0.021 TL 2.789. The size at which 50% of females and males matured was respectively 12.65 cm and 13.91 cm total length (TL). The age at which 50% of females and males matured was respectively 2.9 and 3.5 years.Zosterisessor ophiocephalus je trenutno važna komponenta priobalnog ribolova istočnog Mediterana. U Tunisu je prvi put zabilježen u zaljevu Gabes 1993. godine, gdje je sada važna ribolovna vrsta. U ovoj studiji određivani su parametri starosti i rasta u zaljevu Gabes (jugoistočno od Tunisa) na temelju analize otolita 824 primjerka, ulovljenih između rujna 2006. i kolovoza 2007. godine. Starost je utvrđena na temelju fosilnih naraštajnih prstenova na otolitima (sagitta) vrste Zosterisessor ophiocephalus. Ovi rezultati su nam omogućili procjenu približne starosti pojavom svakog prstena kruga /annulus. Utvrđene su najstarije jednike koje su imale 6 godina za oba spola. Von Bertalenffyjevi parametri zasnovani na podatcima o duljini pri određenoj starosti bili su; TL∞ = 24.83 ± 1.69 cm, K = 0.19 ± 0.03 godina-1 i t0 = - 0.91 ± 0.12 za mužjake i TL∞ = 24.13 ± 1.17 cm, K = 0.20 ± 0.02 godina-1 i t0 = - 0.80 ± 0.09 za ženke. Dužinsko-maseni odnos za oba spola vrste Zosterisessor ophiocephalus je Wt = 0,021 TL 2.789. Veličina kod koje 50% ženki i mužjaka sazrijeva bila je 12,65 cm i 13,91 cm ukupne duljine (TL). Dob kod koje 50% ženki i mužjaka sazrijeva je između 2,9 i 3,5 godina starosti

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