Abstract
Background. Klein’s sole, Synapturichthys kleinii (Risso, 1827), is a rare fish, included in the IUCN Red List as Data Deficient, and its biology is poorly known. Biological investigations of S. kleinii have been surprisingly rare in Tunisian waters. In the presently reported study, we investigated the reproductive period, size at first sexual maturity, and fecundity of S. kleinii along the Tunisian waters, with the aim of achieving the first complete and comprehensive description of the reproduction of this fish in the Mediterranean Sea. Materials and methods. A total of 294 specimens of S. kleinii were sampled over two years, off the Tunisian coasts. Sex ratio was estimated through the seasons of the year and the size classes. The stage of maturity was determined macroscopically only for females. Monthly gonadosomatic index (GSI), monthly hepatosomatic index (HSI), and condition factor (K) were calculated for males and females of S. kleinii. Size at first maturity was estimated only for females during the spawning season. Eighteen mature females at spawning stage were collected, weighed, and fixed in 4% formaldehyde solution for fecundity estimation. Results. Annual sex ratio showed significant differences between males and females. In specimens exceeding 27 cm in total length females outnumbered males significantly. The Klein’s sole reproduction period started in October and ended in January. The gonadosomatic index reached highest values in November for females and males. Females attained sexual maturity at 20.53 cm total body length (TL). Total fecundity ranged from 3647 to 23 174 eggs. We found a low correlation coefficient between total fecundity and total length, but a high correlation coefficient between eviscerated weight and ovary weight. Conclusion. Our results constitute a preliminary baseline for monitoring changes in the biological indexes linked to the reproduction cycle and length at first sexual maturity of S. kleinii. The presently acquired data will enable biologists to assess the status of this fish and develop culture technology in natural waters and will be useful for the fishery biologists and conservation biologists, for successful development, management, production, and ultimate conservation of this favoured Tunisian food fish.
Highlights
Klein’s sole, Synapturichthys kleinii (Risso, 1827), is a rare fish, included in the IUCN Red List as Data Deficient, and its biology is poorly known
In the presently reported study, we investigated the reproductive period, size at first sexual maturity, and fecundity of Synapturichthys kleinii off the Tunisian coasts, with the aim of obtaining a comprehensive description on the reproductive cycle of this fish in the Mediterranean Sea
This work constitutes a contribution to the knowledge of the reproductive biology of an endangered species of Soleidae included in the IUCN Red List as a Data Deficient
Summary
Klein’s sole, Synapturichthys kleinii (Risso, 1827), is a rare fish, included in the IUCN Red List as Data Deficient, and its biology is poorly known. Biological investigations of S. kleinii have been surprisingly rare in Tunisian waters. In the presently reported study, we investigated the reproductive period, size at first sexual maturity, and fecundity of S. kleinii along the Tunisian waters, with the aim of achieving the first complete and comprehensive description of the reproduction of this fish in the Mediterranean Sea. Materials and methods. Size at first maturity was estimated only for females during the spawning season. Eighteen mature females at spawning stage were collected, weighed, and fixed in 4% formaldehyde solution for fecundity estimation. In specimens exceeding 27 cm in total length females outnumbered males significantly. Females attained sexual maturity at 20.53 cm total body length (TL). Our results constitute a preliminary baseline for monitoring changes in the biological indexes linked to the reproduction cycle and length at first sexual maturity of S. kleinii. The presently acquired data will enable biologists to assess the status of this fish and develop culture technology in natural waters and will be useful for the fishery biologists and conservation biologists, for successful development, management, production, and ultimate conservation of this favoured Tunisian food fish
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