Evaluation and diagnosis of the sea-bream Sparus aurata (L. 1758) stock by structural approach in the Mellah lagoon (North-eastern Algeria)

An Analytical approach was applied to gilthead seabream Sparus aurata stock evaluation in Mellah lagoon (North-eastern Algeria). Its temporal changes were followed during the period 1999-2003. Individual sea-breams 17-61 cm long were landed. This species recruits when one year old and the gears used (enclosures, gillnets) mainly captured fish 24 to 52 cm long. The coefficients of mortality due to fishing (F) estimated by the analysis of cohorts varied little according to the size of the fish. With an average of 0.09, the values of F remained unchanged from one year to the next and indicated that the stock was little fished. This is confirmed by the low value of the exploitation rate (E = 0.28). The analysis of the 1999-2003 pseudo-cohort gave annual mean values of recruitment, total abundance and total biomass of 113,617 fingerlings, 1.57 million individuals and 66.7 tons, respectively. Taking account of a stable fishing effort, the decrease in yield between 1999 and 2003 shown by the fishing statistics may have been due to a collapse of recruitment. Indeed recruitment was divided by 5.5 between 1999 and 2003, and generated a fall of 81.8 % of the biomass available during this period. These results are discussed by taking into account the changes in connection between the lagoon and the seaL'approche analytique a été appliquée pour évaluer le stock de daurades Sparus aurata dans la lagune du Mellah (Nord-Est de l'Algérie) ; son évolution temporelle a été suivie au cours de la période 1999-2003. Les captures de cette espèce ont été réalisées à l'aide d'une bordigue et de filets. Elles étaient constituées d'individus d'un an et plus, dont la longueur totale variait entre 17 et 61 cm. Les engins utilisés capturaient principalement les poissons de 24 à 52 cm. Les coefficients de mortalité par pêche (F), estimés par l'analyse des cohortes, varièrent peu en fonction de la taille des poissons. Avec une moyenne de 0,09, ces valeurs restèrent inchangées d'une année à l'autre, indiquant que le stock était peu pêché, ce qui a été confirmé par la faible valeur du taux d'exploitation (E = 0,28). L'analyse de la pseudo-cohorte (1999- 2003) a donné des valeurs moyennes annuelles de recrutement, d'abondance totale et de biomasse totale respectivement de 113 617 alevins, 1,57 millions d'individus et 66,7 tonnes. Tenant compte d'un effort de pêche stable, la diminution de la production relevée dans les statistiques de pêche entre 1999 et 2003 serait due à un effondrement du recrutement. Ce dernier a été divisé par 5,5, ce qui a engendré une chute de 81,8 % de la biomasse disponible au cours de cette période. Ces résultats sont discutés en tenant compte de l'évolution des échanges hydriques entre la lagune et la mer

Neobična pristunost juvenilnih primjeraka vrste Synagrops japonicus u jugozapadnom Mediteranu

This paper reports additional records of the Indo-Pacific fish Synagrops japonicus (Doderlein, 1884) in Western Mediterranean. Twenty juveniles of this species ranging from 4 to 4.8 cm (TL) were caught in Annaba Bay, Algeria, using beach seine, in Summer of 2011 (9 specimens, 4 ≤ TL ≤ 4.6 cm) and 2012 (11 specimens, 4.2 ≤ TL ≤ 4.8 cm). Some hypotheses on the origin of this unusual presence are discussed.U ovom radu se navode dodatni nalazi vrste Synagrops japonicus (Doderlein, 1884) u zapadnom Mediteranu. Uhvaćeno je dvadeset juvenilnih primjeraka ove vrste u rasponu od 4 do 4,8 cm (TL) u Annaba zaljevu, Alžir, pomoću obalne mreže potegače, u ljeto 2011. godine (9 primjeraka, 4 ≤ TL ≤ 4,6 cm) i 2012. (11 primjeraka, 4.2 ≤ TL ≤ 4,8 cm). U radu su iznesene neke hipoteze o podrijetlu ove neobične prisutnosti

Fuzzy species limits in Mediterranean gorgonians (Cnidaria, Octocorallia): inferences on speciation processes

The study of the interplay between speciation and hybridization is of primary importance in evolutionary biology. Octocorals are ecologically important species whose shallow phylogenetic relationships often remain to be studied. In the Mediterranean Sea, three congeneric octocorals can be observed in sympatry: Eunicella verrucosa, Eunicella cavolini and Eunicella singularis. They display morphological differences and E.singularis hosts photosynthetic Symbiodinium, contrary to the two other species. Two nuclear sequence markers were used to study speciation and gene flow between these species, through network analysis and Approximate Bayesian Computation (ABC). Shared sequences indicated the possibility of hybridization or incomplete lineage sorting. According to ABC, a scenario of gene flow through secondary contact was the best model to explain these results. At the intraspecific level, neither geographical nor ecological isolation corresponded to distinct genetic lineages in E.cavolini. These results are discussed in the light of the potential role of ecology and genetic incompatibilities in the persistence of species limits.French National Research Agency (ANR) program Adacni (ANR) [ANR-12-ADAP-0016]CNRSHubert Curien 'Tassili' program [12MDU853]CCMAR Strategic Plan from Fundacao para a Ciencia e a Tecnologia-FCT [PEst-C/MAR/LA0015/2011,FEDERinfo:eu-repo/semantics/publishedVersio

Neobična pristunost juvenilnih primjeraka vrste Synagrops japonicus u jugozapadnom Mediteranu

This paper reports additional records of the Indo-Pacific fish Synagrops japonicus (Doderlein, 1884) in Western Mediterranean. Twenty juveniles of this species ranging from 4 to 4.8 cm (TL) were caught in Annaba Bay, Algeria, using beach seine, in Summer of 2011 (9 specimens, 4 ≤ TL ≤ 4.6 cm) and 2012 (11 specimens, 4.2 ≤ TL ≤ 4.8 cm). Some hypotheses on the origin of this unusual presence are discussed.U ovom radu se navode dodatni nalazi vrste Synagrops japonicus (Doderlein, 1884) u zapadnom Mediteranu. Uhvaćeno je dvadeset juvenilnih primjeraka ove vrste u rasponu od 4 do 4,8 cm (TL) u Annaba zaljevu, Alžir, pomoću obalne mreže potegače, u ljeto 2011. godine (9 primjeraka, 4 ≤ TL ≤ 4,6 cm) i 2012. (11 primjeraka, 4.2 ≤ TL ≤ 4,8 cm). U radu su iznesene neke hipoteze o podrijetlu ove neobične prisutnosti

Ecologie des sars Diplodus cervinus cervinus (Lowe, 1838) et Diplodus puntazzo (Cetti, 1777), de la badèche Epinephelus costae (Steindachner, 1875) et du corb Sciaena umbra (Linnaeus, 1758) dans le golfe d'Annaba (Est, Algérie). Nature et technologie.

Nature et technologieEcologie des sars Diplodus cervinus cervinus (Lowe, 1838) et Diplodus puntazzo (Cetti, 1777), de la badèche Epinephelus costae (Steindachner, 1875) et du corb Sciaena umbra (Linnaeus, 1758) dans le golfe d'Annaba (Est, Algérie)

Microsatellite length variation in candidate genes correlates with habitat in the gilthead sea bream Sparus aurata

International audienc

Connectivity patterns of the yellow gorgonian: Eunicella cavolini in the NW Mediterranean.

Connectivity studies in the marine realm are of great importance to understand the evolutionary potential of populations in a context of growing pressures on the marine environment. Here, we investigated the effect of the local, regional, and depth spatial scale on the population genetic structure of the yellow gorgonian Eunicella cavolini, one of the most common octocoral species of the Mediterranean hard-bottom communities. This species, along with other sessile metazoans typical of coralligenous ecosystems, plays an important role in supporting biodiversity, but is also impacted by direct and indirect consequences of human activities, such as physical destruction or mortality events due to thermal anomalies. Samples were taken from 15 sites located in the Ligurian Sea (NW Mediterranean) in two adjacent regions 100 kilometres apart, i.e. from the areas of Marseille (France) and Portofino (Genoa, Italy), and were analysed using six microsatellite loci. A pattern of isolation by distance was observed at the regional as well as the local scales. Although E. cavolini showed less genetic structure than other Mediterranean octocorallian species, we observed a significant genetic differentiation between populations a few kilometres apart. A low genetic differentiation was also observed. between shallow and deep populations. The occurrence of genetically differentiated populations of E. cavolini at the scale of kilometres has important consequences for the management of this species and of the associated communities

Sparus_aurata_genotypes_data_files

This ZIP archive contains 3 data files (as described in Table 1), "3_CANDIDATE_SSR_10_pops.gtx" is the GENETIX input file matrix for the 3 candidate genes SSRs genotyped in 10 locations, "7_ANONYMOUS_3_CANDIDATE_SSR_5_pops.gtx" is the GENETIX input file matrix for the 7 anonymous SSRs and 3 candidate genes SSRs genotyped in 5 locations, and "Sparus_44loci_AFLPSURV.txt" is the AFLPSURV input file table for the 44 AFLP markers in 10 locations