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Background. The common pandora, Pagellus erythrinus (Linnaeus, 1758), is widely distributed in the Black and the Mediterranean seas. Therefore, P. erythrinus is a valuable component of the commercial fishery in Tunisia and plays an important role in microeconomics of local areas. The goal of this study was to investigate the stock structure and otolith asymmetry for specimens of the common pandora sampled from two lagoons—Ghar El Melh and Bizerte. Materials and methods. We collected a total of 119 specimens of P. erythrinus from the two lagoons, from May through July 2016. The Elliptical Fourier Analysis (EFA) was determined to evaluate the degree of similarity in the otoliths and detect the reciprocal variability. Results. The Discriminant Factor Analysis for the sagitta shape clearly demonstrated an asymmetry when comparing otoliths (left–right) (P < 0.05) within each population and a difference in shape when comparing the same side between the two populations: between the two sides (right–right and left–left). Conclusion. The comparison of the otolith morphology of the two populations showed a clear difference in shape and a left–right asymmetry of otoliths between and within populations. This result is probably related to genetic and local environmental factors. In fact, this investigation improves the knowledge on the stock discrimination for P. erythrinus and provides useful information for analysing fisheries management of this species in Tunisia.

Analyzes the problems of upper secondary education suggesting that the main concerns be the change from a collective to an individualised form of education and opening up educational institutions to adults as centers for continuous learning. (Author/RK)

Background. The thinlip grey mullet, Liza ramada (Risso, 1810), is widespread in Tunisia. Despite its economic importance, the stock discrimination of this fish is poorly understood. The aim of this study is to investigate, for the first time, the stock discrimination of this species for two Tunisian populations based on the otolith shape, using different statistical approaches. Materials and methods. The specimens of L. ramada were collected during three months (from March to May 2013) at two sampling sites: the marine (Cap Zebib sea resort) and the estuarine (Mellegue Dam) in Tunisia. We analysed sagittal otolith shape variation for 120 individuals (60 fish of each study site comprising 30 males and 30 females) for both sexes (males and females) and two sides (left and right otolith) for each specimen. Results. Statistical- and discriminant function analysis of the sagittal otolith shape clearly demonstrated statistically significant differences from the two populations. These results were also confirmed by highly statistically significant difference between otolith shape (left and right) for both sexes. An asymmetry was detected when comparing otoliths of the same side (RR–LL) between different sampling sites. Conclusion. The shape variability of otolith between these two sampling sites is probably correlated with local environmental and ecological factors.

Gilthead seabream Sparus aurata (L.), a protandrous hermaphrodite, was caught in Mellah lagoon (Algeria) from July 1997 to June 1998. Its age, growth and reproduction were studied. Fish ranged in size from 157 to 610 mm total length and weighed from 60 to 4000 g wet weight. There were fish aged 1+ to 7+ years old in the samples. Direct scale readings were made by counting the number of rings. These were compared with the data obtained by backcalculating the lengths at different ages. These two methods were in agreement and showed that the growth rate of gilthead seabream in Mellah lagoon is very high compared to other study areas. The growth parameters of the Von Bertalanffy equation were: L∞ = 55.33 cm, K = 0.513, t0 = - 0.282, with F’ = 7.359. The fitted length-weight relationship was W = 1.292. 10-2 L3.06. The reproductive season extended from October to January, with a peak in December. Sex inversion occurred at a total length of 44 cm. Sexual maturity was reached at 32.6 cm total length. Se capturaron ejemplares de dorada, Sparus aurata (L.), una especie hermafrodita proterándrica, en la laguna de Mellah (Argelia) entre Julio de 1997 y Junio de 1998. Se estudiaron la edad, el crecimiento y la reproducción. La talla de los ejemplares estudiados osciló entre 157 y 610 mm de longitud total, pesando entre 60 y 4000 g (peso fresco). Ejemplares de edades comprendidas entre 1+ y 7+ años estuvieron presentes en las muestras. La lectura directa de algunas escamas mediante el conteo del número de anillos fue comparada con los datos obtenidos por retrocálculo de las tallas a distintas edades. Los resultados de los dos métodos fueron similares y mostraron que la tasa de crecimiento de la dorada en la laguna de Mellah es muy alta en comparación con otras áreas de estudio. Los parámetros de crecimiento de la ecuación de Von Bertalanffy fueron los siguientes: L• = 55.33 cm, K = 0.513, t0 = - 0.282, con F’ = 7.359. El ajuste de la relación talla – peso fue el siguiente: W = 1.292. 10-2 L3.06. La estación reproductiva estuvo comprendida entre Octubre y Enero, con un pico en Diciembre. La inversión de sexo tuvo lugar a una longitud total de 44 cm. La madurez sexual se alcanzó a una longitud total de 32.6 cm.

The aim of this study is to investigate stock discrimination of the Black Scorpionfish Scorpaena porcus (family Scorpaenidae) sampled from three Tunisian stations (Hammam Lif, Rafraf, Djerba). The method used is otolith shape analysis and the paper describes the methodology and the results. The basis of this method is the detection of phenotypic polymorphism between the three populations of fish, between pairs of otoliths from each station and between the pairs of otoliths of different stations. Discriminating analysis was used to illustrate the differences and similarities between the observed groups and optimize the variability existing between them. The interpretation of results shows the presence of three distinct populations with a slight overlap. They show a left-right otolith symmetry for the groups of Hammam Lif and Rafraf unlike that of Djerba which detects an asymmetry. An asymmetry is also detected when comparing otoliths of the same side (RR-LL) between different stations.

This study provides data on the genetic structuring of the pipefish Syngnathus abaster in the western Mediterranean and Adriatic Seas. A total of 109 specimens were collected in brackish-water biotopes. The control region and three other regions of the mitochondrial genome were analysed. The most relevant result was the high genetic structuring found by Bayesian inference (BI), maximum likelihood (ML) and network analyses, which were consistent in showing three well-separated clusters of S. abaster populations. Furthermore, BI and ML did not support the monophyly of the taxon S. abaster. These results suggest the occurrence of a species complex in the study area, whose differentiation may have occurred since the Pleistocene. The results also show a very high genetic variability at the inter-population level, with no shared haplotypes among sites. Evolutionary forces due to the fragmented nature of the brackish-water habitats may account for the high genetic divergence found among the groups and populations. Finally, although dispersal by rafting over long distances may occasionally occur, this study suggests linear stepping-stone model of colonization to be most likely. The complexity of the results obtained suggests that further studies are needed to elucidate the phylogeny of S. abaster. This work was supported by MIUR (Ministero per l’Istruzione, l’Università e la Ricerca) FAR grants to M.C. and P.F.

En Janvier 2008, trois lots d’anchois ont été capturés dans les eaux tunisiennes : un lot dans la lagune de Bizerte, un lot dans le littoral de Korba et un lot prés de l’ile Zembra (les trois sites dans la Tunisie septentrionale). Une étude otolithometrique a été appliquée afin d’étudier l’hétérogénéité des stocks d’anchois colonisant les eaux tunisiennes. En effet, l’étude de la forme des otolithes basée sur l’analyse elliptique de Fourier, est une nouvelle et puissante technique. Les descripteurs de Fourier sont caractérisés par des harmoniques que chacune est représentée par quatre coefficients. L’analyse statistique de ces coefficients permet la séparation des individus étudiés. L’application de cette technique nous a permis de séparer par une analyse canonique discriminante trois populations d’anchois récoltés dans les eaux tunisiennes. Recently it has been confirmed genetically, the heterogeneity of anchovy colonizing the Mediterranean. In this work, we became interested in the study of this heterogeneity in Tunisian waters, through analysis and comparison of shapes of otoliths. Indeed, this method based on elliptic Fourier analysis is a powerful new technique. The Fourier descriptors are characterized by harmonics that each is represented by four coefficients. Statistical analysis of these factors allows the separation of specimens studied. Applying this technique allowed us to separate three populations of anchovies catched in Tunisian waters. Published Anchovy, otolith, shape, elliptic Fourier analysis

The first records of Lampris guttatus in the Mediterranean Sea date back to 1807. Yet, until now it has been considered as a rare species (less than 25 specimens recorded in the literature). Since 2008, at least 23 specimens have been fished or observed along the French Mediterranean coast. In this paper, we present an updated review of records in the Mediterranean and discuss the possible link with the present sea water warming. We hypothesise that the recent Mediterranean specimens could come from the Atlantic, throughout the Gibraltar Strait, following a northward migration along the Northeast Atlantic coast due to present global warming.

Atherina boyeri de la Méditerranée est un complexe hautement polymorphe ayant un génotype capable d’une réponse phénotypique flexible. Elle peut rapidement adapter les traits de sa morphologie à des environnements allant des eaux douces aux eaux saumâtres côtières polyhalines et aux eaux océaniques. Les travaux de recherche réalisés, en Méditerranée, sur ce complexe ont permis de le scinder en trois espèces. Deux espèces marines (Atherina boyeri et Atherina punctata) et une espèce qui peuplent les lagunes et les côtes des îles Kerkennah (Atherina lagunae) (Trabelsi et al. 2009). Dans le présent travail l’analyse d’une portion du gène cytochrome b a été utilisée pour étudier les variations génétiques d’une population d’athérine, prélevée des côtes de l’île de Djerba, afin de situer cette population au sein du complexe Atherina boyeri. Nos analyses moléculaires ont montré que les athérines de l’île de Djerba tout comme celles des îles Kerkennah appartiennent à l’espèce Atherina lagunae. Toutes les analyses phylogénétiques ont montré que les athérines insulaires de l’île de Djerba constituent avec les athérines du lac de Tunis et celles des îles Kerkennah un clade qui est fortement supporté par les analyses statistiques. D’autre part, les séquences des athérines insulaires de l’île de Djerba et des îles Kerkennah montrent un taux élevé de divergence intrapopulationnel. Cependant les analyses d’une portion du gène cytochrome b des poissons du lac de Tunis présentent un faible taux d’hétérogenité. Ces résultats pourraient suggérer un modèle de métapopulation avec des structures core-sattelites dont les poissons insulaires représentent les cores; alors que ceux du lac de Tunis seraient une population satellite. L’ancêtre des atéhrines lagunaires pourrait être un poisson marin qui s’est adapté au milieu insulaire en premier lieu et qui a colonisé les lagunes en second lieu ou alors les poissons d’origine lagunaire ont fini par peupler les côtes insulaires. Cependant, le premier scénario pourrait être le plus plausible d'après l'hypothèse du model core- satellite, parce qu'il expliquerait la colonisation des milieux lagunaires avec une réduction de la diversité du gène. يعتبر سمك الأترينا الذي يعيش في البحر الأبيض المتوسط من الأسماك التي لها قدرة فائقة على التأقلم في العيش في جميع أنواع المياه. أكدت الدراسات الأخيرة أن سمك الأترينا ينقسم إلي 3 فصائل: * فصيلتان تعيشان في البحار. Atherina punctata et Atherina boyeri * فصيلة ثالثة تعيش في البحيرات و على ضفاف جزر قرقنة Atherina lagunae . الهدف من هذه الدراسة هو معرفة إنتماء سمك الأترينا المتواجد بجزيرة جربة إلى أي فصيلة من الفصائل التي وقع ذكرها سابقا. أظهرت دراسة الخاصيات الجينية لقطعة من جين Cyt b إنتمائها إلى الفصيلة الثالثة Atherina lagunae مثلها مثل أسماك جزر قرقنة. كما أكدت الدراسة الفيلوجينية إنتماء أسماك بحيرة تونس و جزر قرقنة و جزيرة جربة إلى نفس المجموعة الجينية مما يمكننا من تصنيف هذه الأسماك ضمن core satellite Metapopulation. The Mediterranean Atherina boyeri species complex has been recently divided into three species, two living in marine environments (A. boyeri and A. punctata) and one found in lagoons and in shallow coasts of the Tunisian Kerkennah islands (A. lagunae) (Trabelsi et al. 2009). Genetic variation in a portion of the cytochrome b gene was examined for two populations belonging to the A. boyeri complex which have been caught in shallow waters of another Tunisian southern Island (Djerba). Similarly to the Kerkennah fish, molecular studies have shown that fish from Djerba, inspite of their marine habitat, belong to the A. lagunae species. All the phylogenetic analysis showed that the sequences of the Djerba insular fish constitute with the lagoon Atherina of the Lake of Tunis and Kerkennah insular fish a clade which is strongly statistically supported. In addition, within this clade, the both sequences from fish caught Djerba and Kerkennah coasts exhibit a great level of intrapopulational divergence between them. Whereas, analysis of partial cytochrome b gene of fish from the Lake of Tunis suggests a very low level of sequence heterogeneity. These results could suggest a metapopulation pattern with core-satellite structure in which cores are insular populations; whereas population of Lake of Tunis would be an example of satellite population. The ancestors of the A. lagunae can considered marine fish adaptated in a first step to shallow waters of the island coasts and in a second step, they have colonized lagoons; or some lagoon fish could have migrated and lived on similar habitats such as island coasts. However, according to the core-satellite hypothesis, the first scenario could be the most realistic according to the fish colonization of lagoon habitats with reduction of its gene diversity. Published

International audience; Investigations conducted off the coast of Languedoc (southern France, northern Mediterranean) during 14 years show that common eagle rays Myliobatis aquila (Linnaeus, 1758) were caught especially from August to October. The smallest male and female adults were 500 mm and 730 mm disc width (DW), respectively, and weighed 2000 g and 6100 g. The largest male and the largest female were 720 mm and 1140 mm DW, respectively and weighed 5250 g and 29400 g, respectively. There was a significant relationship of total mass versus DW between males and females. Diameter of the largest yolky oocytes ranged from 26 to 32 mm, number of yolky oocytes counted in five females ranged between 8 and 10. Fertilized eggs were enveloped in a diaphanous capsule. Each capsule containing six eggs weighing between 4.5 and 5.3 g (mean: 4.9 ± 0.9). Breeding period probably occurred from August to September. The common eagle ray probably reproduced in alternate year, and embryonic development did not exceed one year. Ovarian fecundity and uterine fecundity were rather low, both between 8 and 12.

International audience

International audience

International audience

Reports of morphological differences between European anchovy (Engraulis cf. encrasicolus) from coastal and marine habitats have long existed in the ichthyologic literature, and have given rise to a long-standing debate on their taxonomic status. More recently, molecular studies have confirmed the existence of genetic differentiation between the two anchovy ecotypes. Using ancestry-informative markers, we show that coastal anchovies throughout the Mediterranean share a common ancestry, and that substantial genetic differentiation persists in different pairs of coastal/marine populations despite the presence of limited gene flow. On the basis of genetic and ecological arguments, we propose that coastal anchovies deserve a species status of their own (E. maeoticus) and argue that a unified taxonomical framework is critical for future research and management. This article is protected by copyright. All rights reserved.