O pojavi dugoperajne psine mako, Isurus paucus (Chondrichthyes: Isuridae) kod Alžirske obale (južnoistočni Mediteran)

The authors describe in this paper one male and one female longfin makos Isurus paucus Guitart Manday, 1966 caught off Béni-Saf, city located on the Algerian coast, close to the Moroccan border. These captures confirm the occurrence of the species in the Algerian waters and in the Mediterranean.Autori opisuju u ovom radu primjerak mužjaka i ženke dugoperajne psine mako, Isurus paucus Guitart Manday, 1966 uhvaćene kod Béni-Saf, grada na alžirskoj obali u blizini granice s Marokom. Ovaj ulov potvrđuje pojavu vrste u alžirskim vodama i u Mediteranu

The second record of Crested oarfish Lophotus lacepede (Lophotidae) from the Algerian coast (southern Mediterranean Sea)

The authors report on the capture of a specimen of crested oarfish, Lophotus lacepede Giorna, 1809 from the Algerian coast. It was a large sized specimen which measured 150 cm total length (TL) and 142 cm standard length (SL) and weighed 3.5 kg. The specimen was described including some morphometric measurements and meristic counts. This rare finding represents the second record of the species for the Algerian waters. It constitutes also the westernmost extension range of the species for the Maghreb shore but also for the Mediterranean Sea

The second record of Crested oarfish Lophotus lacepede (Lophotidae) from the Algerian coast (southern Mediterranean Sea)

The authors report on the capture of a specimen of crested oarfish, Lophotus lacepede Giorna, 1809 from the Algerian coast. It was a large sized specimen which measured 150 cm total length (TL) and 142 cm standard length (SL) and weighed 3.5 kg. The specimen was described including some morphometric measurements and meristic counts. This rare finding represents the second record of the species for the Algerian waters. It constitutes also the westernmost extension range of the species for the Maghreb shore but also for the Mediterranean Sea

O pojavi dugoperajne psine mako, Isurus paucus (Chondrichthyes: Isuridae) kod Alžirske obale (južnoistočni Mediteran)

The authors describe in this paper one male and one female longfin makos Isurus paucus Guitart Manday, 1966 caught off Béni-Saf, city located on the Algerian coast, close to the Moroccan border. These captures confirm the occurrence of the species in the Algerian waters and in the Mediterranean.Autori opisuju u ovom radu primjerak mužjaka i ženke dugoperajne psine mako, Isurus paucus Guitart Manday, 1966 uhvaćene kod Béni-Saf, grada na alžirskoj obali u blizini granice s Marokom. Ovaj ulov potvrđuje pojavu vrste u alžirskim vodama i u Mediteranu

The reproductive biology of the school shark, Galeorhinus galeus Linnaeus 1758 (Chondrichthyes: Triakidae), from the Maghreb shore (southern Mediterranean)

The school shark, Galeorhinus galeus, is commonly captured off the Maghreb shore along the Algerian and Tunisian coasts of the southern Mediterranean. Of 517 specimens collected during more than twenty years, the smallest adult male was 1225 mm total length (TL) and weighed 11 580 g, the largest adult male was 1580 mm and weighed 18 000 g, and the heaviest male was 1570 mm and weighed 19 900 g. All males above 1260 mm TL were adult. Adult females were 1400-1900 mm TL. The smallest pregnant female was 1400 mm TL and carried developing embryos. The largest female was 1990 mm TL and weighed 27 900 g. Females were generally heavier than males, but there was no significant difference between males and females in mass versus total length relationship. Two ovulation and two pupping seasons occurred in winter and in spring. Gestation was estimated at twelve months, with most females appearing to reproduce in alternate years. The diameter of the largest yolky oocytes ranged 43-47 mm (mean 44.7±1.8) and the mass ranged 45-52 g (mean 47.9±2.2). Both uteri were compartmentalized into chambers and a single embryo developed in each chamber. Length and weight at birth, based on near-term embryos, were estimated at 240-320 mm TL and 88-109 g. The chemical balance of development, based on the mean dry mass of the largest yolky oocytes and of near-term fetuses, was about 1, showing that G. galeus can be considered as an incipient histotrophic species. Ovarian fecundity was higher than uterine fecundity. Litter sizes ranged 8-41. Males generally outnumbered females, especially among free-swimming adult specimens

To Be, or Not to Be: That Is the Hamletic Question of Cryptic Evolution in the Eastern Atlantic and Mediterranean Raja miraletus Species Complex

The ability to correctly identify specimens at the species level is crucial for assessing and conserving biodiversity. Despite this, species-specific data are lacking for many of South Africa’s catsharks due to a high level of morphological stasis. As comprehensive and curated DNA reference libraries are required for the reliable identification of specimens from morphologically similar species, this study reviewed and contributed to the availability of cytochrome c oxidase subunit I (COI) and nicotinamide adenine dehydrogenase subunit 2 (NADH2) sequences for South Africa’s catsharks. A molecular taxonomic approach, implementing species delimitation and specimen assignment methods, was used to assess and highlight any taxonomic uncertainties and/or errors in public databases. The investigated species were summarised into 47 molecular operational taxonomic units (MOTUs), with some conflicting specimen assignments. Two Apristurus specimens sampled in this study remained unidentified, revealing the presence of previously undocumented genetic diversity. In contrast, haplotype sharing within Haploblepharus—attributed to nucleotide ambiguities—resulted in the delimitation of three congeners into a single MOTU. This study reveals that molecular taxonomy has the potential to flag undocumented species and/or misidentified specimens, and further highlights the need to implement integrated taxonomic assessments on catsharks that represent an irreplaceable component of biodiversity in the region

Commercial sharks under scrutiny: baseline genetic distinctiveness supports structured populations of small-spotted catsharks in the Mediterranean Sea

The present study, based on microsatellite markers, describes a population genetic analysis of the small-spotted catshark Scyliorhinus canicula (Linnaeus, 1758), representing one of the most abundant and commonly caught cartilaginous fishes in the Mediterranean Sea and adjacent areas. The analyses were performed to unravel the genetic features (variability, connectivity, sex-biased dispersal) of their relative geographic populations, both at the small (around the coast of Sardinia, Western Mediterranean Sea) and at a larger spatial scale (pan-Mediterranean level and between the Atlantic Ocean and the Mediterranean Sea). Individual clustering, multivariate and variance analyses rejected the hypothesis of genetic homogeneity, with significant genetic differences between the Mediterranean and Atlantic, as well as within the Mediterranean area between the Western and Eastern basins. In details, our results seem to confirm that the Strait of Gibraltar could not represent a complete barrier to the exchange of individuals of small-spotted catshark between the Atlantic Ocean and the Mediterranean Sea. In the latter area, a complex genetic structuring for S. canicula was found. Apart from differences among the Western, Eastern and Adriatic sites, within the Western basin the small-spotted catsharks around Sardinian waters are strongly differentiated from all others (both from the eastern Tyrrhenian Sea and southernmost part of the Algerian basin) and are demographically stable. Several possible mechanisms, both biological and abiotic (e.g., migratory behavior, water fronts and oceanographic discontinuities), are discussed here to explain their peculiar characteristics. Overall, the genetic data presented, both at the local and regional level, could represent a baseline information, useful for the temporal monitoring of populations, and to assess the effects of present or future fishing/management/conservation measures

Strongly structured populations and reproductive habitat fragmentation increase the vulnerability of the Mediterranean starry ray Raja asterias (Elasmobranchii, Rajidae)

1. The Mediterranean starry ray (Raja asterias) populations within the Mediterranean Sea are susceptible to high rates of bycatch in the multispecies trawl fisheries. Understanding its population structure and identifying critical habitats are crucial for assessing species vulnerability and setting the groundwork for specific management measures to prevent population decline. 2. To assess the population structure of R. asterias in the Mediterranean, the genetic variation in nine population samples at one mitochondrial marker and eight nuclear microsatellite loci was analysed. Moreover, 172 egg cases collected in the Strait of Sicily were identified at species level using integrated molecular and morphological approaches. 3. Genetic analyses revealed that the Mediterranean starry ray comprises three distinct units inhabiting the western, the central-western, and the central-eastern areas of the Mediterranean. An admixture zone occurs in the Strait of Sicily and the Ionian Sea, where individuals of the central-western and central-eastern population units intermingle. 4. The joint morphometric–genetic analyses of rajid egg cases confirmed the presence of more than one species in the admixture area, with a predominance of egg cases laid by R. asterias. DNA barcoding revealed that egg cases and embryos of R. asterias shared several haplotypes with adult individuals from the centralwestern and central-eastern Mediterranean Sea, revealing that females of both populations laid numerous eggs in this area. 5. According to these findings, detailed taxonomic determination of egg cases, when combined with seasonal migration studies, could improve the capability to identify important spawning or nursery areas for the Mediterranean starry ray, particularly in those admixture zones relevant to maintaining genetic diversity. 6. Finally, these new insights should be considered to update the Action Plan for the Conservation of Cartilaginous Fishes in the Mediterranean Sea with effective measures to reduce the impact of skate bycatch in trawling and safeguard egg cases in nursery areas

Call me by my name: unravelling the taxonomy of the gulper shark genus Centrophorus in the Mediterranean Sea through an integrated taxonomic approach

The current shift of fishery efforts towards the deep sea is raising concern about the vulnerability of deep-water sharks, which are often poorly studied and characterized by problematic taxonomy. For instance, in the Mediterranean Sea the taxonomy of genus Centrophorus has not been clearly unravelled yet. Since proper identification of the species is fundamental for their correct assessment and management, this study aims at clarifying the taxonomy of this genus in the Mediterranean Basin through an integrated taxonomic approach. We analysed a total of 281 gulper sharks (Centrophorus spp.) collected from various Mediterranean, Atlantic and Indian Ocean waters. Molecular data obtained from cytochrome c oxidase subunit I (COI), 16S ribosomal RNA (16S), NADH dehydrogenase subunit 2 (ND2) and a portion of a nuclear 28S ribosomal DNA gene region (28S) have highlighted the presence of a unique mitochondrial clade in the Mediterranean Sea. The morphometric results confirmed these findings, supporting the presence of a unique and distinct morphological group comprising all Mediterranean individuals. The data strongly indicate the occurrence of a single Centrophorus species in the Mediterranean, ascribable to C. cf. uyato, and suggest the need for a revision of the systematics of the genus in the area

Improving the conservation of Mediterranean Chondrichthyans : the ELASMOMED DNA barcode reference library

Cartilaginous fish are particularly vulnerable to anthropogenic stressors and environmental change because of their K-selected reproductive strategy. Accurate data from scientific surveys and landings are essential to assess conservation status and to develop robust protection and management plans. Currently available data are often incomplete or incorrect as a result of inaccurate species identifications, due to a high level of morphological stasis, especially among closely related taxa. Moreover, several diagnostic characters clearly visible in adult specimens are less evident in juveniles. Here we present results generated by the ELASMOMED Consortium, a regional network aiming to sample and DNA-barcode the Mediterranean Chondrichthyans with the ultimate goal to provide a comprehensive DNA barcode reference library. This library will support and improve the molecular taxonomy of this group and the effectiveness of management and conservation measures. We successfully barcoded 882 individuals belonging to 42 species (17 sharks, 24 batoids and one chimaera), including four endemic and several threatened ones. Morphological misidentifications were found across most orders, further confirming the need for a comprehensive DNA barcoding library as a valuable tool for the reliable identification of specimens in support of taxonomist who are reviewing current identification keys. Despite low intraspecific variation among their barcode sequences and reduced samples size, five species showed preliminary evidence of phylogeographic structure. Overall, the ELASMOMED initiative further emphasizes the key role accurate DNA barcoding libraries play in establishing reliable diagnostic species specific features in otherwise taxonomically problematic groups for biodiversity management and conservation actions.peer-reviewe