DNA barcoding based on the cytochrome c oxidase subunit I (COI) gene in mitochondrial DNA has been adopted as a global biological identification system for animals due to its accuracy compared with other classical taxonomic methods. The objective of this study was to establish a reference library with generated barcodes. A total of 84 fish specimens belonging to 37 commercially important marine fish species, representing five orders, 14 families and 30 genera, were sampled along the Tunisian coast and barcoded for the first time, obtaining 637 bp sequences. The average Kimura 2-parameter (K2P) distances within species, genera and families were 0.52, 6.86 and 14.60%, respectively. The Maximum likelihood (ML) tree revealed distinct clusters in concurrence with the taxonomic status of the species. Our results confirmed the authentication of the barcode approach for the identification of the species examined and provide valuable information that would help ichthyologists to achieve better monitoring, conservation and management of fisheries in Tunisia.

The Axillary Seabream Pagellus acarne is of economic importance for recreational and commercial fisheries in the Atlantic and the Mediterranean, but a decline in total landings has been observed and raised some concern. Although biological information on the species has been provided for the Atlantic and Mediterranean, in the Portuguese continental slope data is restricted to the southern part of the country, which points to the relevance of the present work. A total of 520 individuals, between 7.8 cm and 39.9 cm TL, were monthly collected from September 2020 to August 2022 from commercial landings of fishing vessels operating off mainland Portugal, and used to study age and growth, the reproductive strategy and the annual sexual cycle. Age varied between 0 years (7.8 cm TL) and 15 years (34.2 cm TL) and the von Bertalanffy growth parameters were estimated from whole-otolith readings (L∞ = 35.2 cm, k = 0.133 yr–1 and t 0 = –2.78 yr). Pagellus acarne proved to be a protandric hermaphrodite species with males prevailing until 28.0 cm TL and females between 28.0 cm and 34.0 cm TL with a brief sex change phase. Females presented asynchronous oocyte development with a batch spawning pattern. The spawning season occurred from April to October with a spawning peak between June and August aas shown by histological analysis of the gonads and high levels of GSI during the period.