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Thanks to the availability of the MEDITS survey data, a standardized picture of the occurrence and abundance of demersal Chondrichthyes in the northern Mediterranean has been obtained. During the spring-summer period between 2012 and 2015, 41 Chondrichthyes, including 18 sharks (5 orders and 11 families), 22 batoids (3 orders and 4 families) and 1 chimaera, were detected from several geographical sub-areas (GSAs) established by the General Fisheries Commission for the Mediterranean. Batoids had a preferential distribution on the continental shelf (10-200 m depth), while shark species were more frequent on the slope (200-800 m depth). Only three species, the Carcharhiniformes Galeus melastomus and Scyliorhinus canicula and the Torpediniformes Torpedo marmorata were caught in all GSAs studied. On the continental shelf, the Rajidae family was the most abundant, being represented in primis by Raja clavata and then by R. miraletus, R. polystigma and R. asterias. The slope was characterized by the prevalence of G. melastomus in all GSAs, followed by S. canicula, E. spinax and Squalus blainville. Areas under higher fishing pressure, such as the Adriatic Sea and the Spanish coast (with the exception of the Balearic Islands), show a low abundance of chondrichthyans, but other areas with a high level of fishing pressure, such as southwestern Sicily, show a high abundance, suggesting that other environmental drivers work together with fishing pressure to shape their distribution. Results of generalized additive models highlighted that depth is one of the most important environmental drivers influencing the distribution of both batoid and shark species, although temperature also showed a significant influence on their distribution. The approach explored in this work shows the possibility of producing maps modelling the distribution of demersal chondrichthyans in the Mediterranean that are useful for the management and conservation of these species at a regional scale. However, because of the vulnerability of these species to fishing exploitation, fishing pressure should be further incorporated in these models in addition to these environmental drivers.

The identification of nursery grounds and other essential fish habitats of exploited stocks is a key requirement for the development of spatial conservation planning aimed at reducing the adverse impact of fishing on the exploited populations and ecosystems. The reduction in juvenile mortality is particularly relevant in the Mediterranean and is considered as one of the main prerequisites for the future sustainability of trawl fisheries. The distribution of nursery areas of 11 important commercial species of demersal fish and shellfish was analysed in the European Union Mediterranean waters using time series of bottom trawl survey data with the aim of identifying the most persistent recruitment areas. A high interspecific spatial overlap between nursery areas was mainly found along the shelf break of many different sectors of the Northern Mediterranean indicating a high potential for the implementation of conservation measures. Overlap of the nursery grounds with existing spatial fisheries management measures and trawl fisheries restricted areas was also investigated. Spatial analyses revealed considerable variation depending on species and associated habitat/depth preferences with increased protection seen in coastal nurseries and minimal protection seen for deeper nurseries (e.g. Parapenaeus longirostris 6%). This is partly attributed to existing environmental policy instruments (e.g. Habitats Directive and Mediterranean Regulation EC 1967/2006) aiming at minimising impacts on coastal priority habitats such as seagrass, coralligenous and maerl beds. The new knowledge on the distribution and persistence of demersal nurseries provided in this study can support the application of spatial conservation measures, such as the designation of no-take Marine Protected Areas in EU Mediterranean waters and their inclusion in a conservation network. The establishment of no-take zones will be consistent with the objectives of the Common Fisheries Policy applying the ecosystem approach to fisheries management and with the requirements of the Marine Strategy Framework Directive to maintain or achieve seafloor integrity and good environmental status.

Fully protected areas (FPAs) help preserving biodiversity and reversing the global decline of fishery resources. Stocks of the European spiny lobster Palinurus elephas (Fabr. 1787), among the most precious gourmet seafood worldwide, are currently facing a dramatic decline. Previous attempts of recovery based on fishery restrictions or active post-larval restocking in marine reserves provided unsuccessful outcomes. Here we present results of a 5-year restocking program carried through a Collaborative Fishery Research (CFR) project, in three ad-hoc established FPAs replenished using below-legal size wild juveniles. Results showed that Catch per Unit Effort (CPUE) in terms of both density and biomass burst (by ca. 300–700%) just 2 years since FPAs establishment, regardless of location. We also report tangible spillover effects (ca. 30–50% increase in density and biomass CPUE outside the FPAs) by the end of the program. Data from a 15-years lasting monitoring of a pilot FPA established in 1998, where the restocking protocol was conducted and protection kept in force once restocking ceased, demonstrated the persistence in time of restocking’ benefits. We foster that creation of FPAs assisted with local restocking under oriented CFR programs can represent an option for the recovery of European spiny lobster stocks from overfishing.

The intercalibration of age readings represents a crucial step in the ageing procedure; the use of different sampling methods, structures, preparation techniques, and ageing criteria can significantly affect age and growth data. This study evaluated the precision and accuracy of ageing for the most important North Atlantic (NA) and Mediterranean (M) ray species, Raja clavata, Raja brachyura, Torpedo marmorata, and Dipturus oxyrinchus, through exchange exercises carried out by readers from different laboratories. In addition, growth parameters were estimated from the obtained data. A total of 663 individual batoids were analysed. R. clavata and R. brachyura samples were obtained from both the NA and the M, while vertebral centra of T. marmorata and D. oxyrinchus were only available for the M. High reading variability was observed for all four evaluated species in terms of CV, APE, and PA. D. oxyrinchus and T. marmorata showed relatively slow growth and the von Bertalanffy model with fixed t0 and Gompertz’s model were, respectively, the most precise models for each of these species. In R. brachyura, females had a faster growth rate compared to combined sexes. The vbt0p proved the most precise model for describing growth in this species, and no statistical differences were found between the NO and the M. For R. clavata, the best-fitting model was the vbt0p for females and males in the NO and for females from the M, while the best-fitting model for males from the M and sexes combined for both areas was log.p. Distinct growth patterns were observed between the two study areas.

Eggcases of eight rajiform skates ( Dipturus nidarosiensis , D. oxyrinchus , Leucoraja melitensis , Raja asterias , R. brachyura , R. clavata , R. miraletus and R. polystigma ) present in the central-western Mediterranean are described, based on specimens obtained from fishery surveys. Eggcase features such as dimensions, horns and apron lengths, and presence/absence of lateral keels were crucial to discriminate the eggcases of the various species. Morphological and morphometric data, confirmed by the multivariate analysis, indicated that the eggcase of R. miraletus and L. melitensis were distinct from those of the other species for being unkeeled. Within the species having keeled eggcases, those of the genus Dipturus and R. brachyura were discriminated from the remaining group by having the largest dimensions and aprons. Sandy bottoms (<100–150 m depth) were identified as egg-laying sites (i.e. sites with females bearing eggcases in uteri ) for many species belonging to genus Raja Raja asterias , R. brachyura , R. miraletus and R. polystigma ). The finding of R. asterias and R. miraletus carrying eggcases yearly on the same sites, seems to confirm the theory that many rajid species demonstrate site fidelity, returning to the same depositional area on an annual basis. Some remarks on reproductive biology of these skates are also provided. The eggcase identification key reported here represents the first for the Mediterranean and may be useful, in the future, to identify egg-laying grounds of skates with a nonlethal method.

It has been amply demonstrated that trawl fishing affects overall biomass, size and species structure of demersal fish communities, and an increasing number of studies are proving that this could have even greater unexpected effects on biological diversity. The aims of this study are: (1) to examine the temporal trends of several ecological diversity indices for middle-slope communities in specific locations within the Sardinian seas, which have been recently subject to increasing fishing capacity; and (2) to simulate the Shannon's entropy (H′) temporal trend, using a multiple linear regression, in order to investigate about the relationships between fishing effort and species diversity. The data come from 11 MEDITS trawl surveys (1994 to 2004). Temporal trends in fishing effort were analysed and ecological diversity indices were measured. Analysis was conducted for four areas (NW, NE, SE, SSW). Significant variations over time in both fishing pressure and ecological diversity indices were found for the southern zones. More precisely, the SE zone showed an increase in fishing effort (+120% in 2004), and a decrease of Shannon–Weiner's diversity. The SSW zone exhibited a 22.6% increase of fishing effort and a decrease of species richness. The best model of H′ incorporates species richness and fishing effort expressed as number of boats per trawling area. Our results seem to indicate that fishing pressure affected the species richness and the abundance of middle-slope species and that variation in ecological diversity indices differed with different levels of fishing effort.

In this paper, we report data related to the reproductive biology of a cosmopolitan mesobathyal lobster, Polycheles typhlops (Decapoda: Polychelidae), caught in the Sardinian waters between 400 and 1400 m of depth. Macroscopic and microscopic analyses were performed on 1104 females and 895 males. The observation on the gonads leads us to conclude that there are seven and four stages of development for the females and for males, respectively. Monthly variations of the percentage distribution related to various stages of development of the ovary and the presence of ovigerous females indicated that the species does not seem to follow a marked seasonal reproductive model, with a long main period for egg hatching that seems to occur between spring and autumn.

We present the first data on the population structure, reproduction, and feeding ecology of Polycheles sculptus S. I. Smith, 1880 from the Sardinian sea. Samples were collected during experimental trawl surveys carried out in 2006-2007 in Sardinian waters, at depths between 1037 and 1598 m. A total of 72 specimens of P. sculptus, 31 males, 40 females, and 1 specimen of undetermined sex, was examined. The sex ratio of the whole sample showed a slight preponderance of females. No significant deviations from the expected 1: 1 relationship were, however, found along the investigated depth range. A clear seasonality in reproduction was not determined. The species showed a high value of the stomach vacuity index (Cv). The diet was based on eight broad categories of preys, but no dominant prey was recognized. Females showed the greatest width in their diet, though Morisita's index indicated a large overlap between sexes. Vengono presentati i primi dati riguardanti la struttura di popolazione, la riproduzione e l'ecologia trofica di Polycheles sculptus S. I. Smith, 1880 nelle acque del Mediterraneo Centro-Occidentale. I campioni analizzati in questo lavoro derivano da campagne di pesca a strascico sperimentali, condotte negli anni 2006-2007, nei mari circostanti la Sardegna, alle batimetriche comprese tra 1037 e 1598 m. Globalmente sono stati esaminati 72 individui di P. sculptus, 31 maschi, 40 femmine ed un esemplare per cui non è stato possibile determinare il sesso. La sex ratio totale si è rivelata leggermente a favore delle femmine; il trend in relazione alla profondità non è stato statisticamente confermato. Dalle analisi non è emerso un chiaro pattern riproduttivo stagionale. Il coefficiente di vacuità dello stomaco (Cv) è risultato caratterizzato da valori sempre piuttosto elevati, in linea con le conoscenze pregresse circa le abitudini alimentari della specie. La dieta si basa sullo sfruttamento di 8 categorie di prede, di cui nessuna dominante. Le femmine hanno mostrato una maggiore ampiezza di dieta, ciononostante l'indice di Morisita ha evidenziato una discreta sovrapposizione per la dieta dei due sessi.

Abstract Anomalies of the number of rostral spines have been recorded in blind lobsters, Polycheles typhlops, caught in Sardinian waters (Central Western Mediterranean). The abnormal specimens, 66 out a total of 789 individuals analysed, showed all the morphometric characteristics of P. typhlops except for the unusual presence of two rostral spines instead of the canonical one. The analysis of partial nucleotide sequences of the mitochondrial cytochrome oxidase subunit I gene (COI) showed that the individuals with two spines were not genetically different from the normal specimens of P. typhlops, while both were quite dissimilar from the other Mediterranean species, P. sculptus. Our results suggest the need of an update of the morphological classification guides for this family combined with a wider genetic study.

Data are provided related to the reproductive biology of a deep-sea lobster, Polycheles typhlops, caught in Sardinian waters between 400 and 1400 m depth. Analyses were performed on 1180 females and 935 males. In both sexes, the carapace length decreased markedly and regularly with increasing depth; the females proved to be prevalent at greater bathymetric depths. The temporal evolution of the gonadosomatic index, and of the percentage distribution of the various stages of ovarian development, did not reveal any clear seasonality in reproduction for the species. /// In questo lavoro vengono presentati dati su alcuni aspetti della riproduzione di Polycheles typhlops, catturato nelle acque sarde tra i 400 e i 1400 m. Le analisi sono state condotte su 1180 femmine e 935 maschi. In entrambi i sessi la lunghezza carapace decresce, marcatamente e regolarmente, all'aumentare della profondità e le femmine sono dominanti alle batimetriche più profonde. L'evoluzione temporale dell'indice gonadosomatico e della distribuzione percentuale dei vari stadi di sviluppo ovarico non rivelano una chiaro modello riproduttivo stagionale per questa specie.