The MECO (Mediterranean Elasmobranchs Citizen Observations) project

Chondrichthyans are apex predators influencing the trophic web through a top-down process thus their depletion will affect the remaining biota. Notwithstanding that, research on chondrichthyans is sparse or data-limited in several biogeographic areas worldwide, including the Levantine Sea. We revise and update the knowledge of chondrichthyans in Cyprus based on a bibliographic review that gains information retrieved from peer-reviewed and grey literature, Global Biodiversity Information Facility (135 records of at least 18 species) and the Ocean Biodiversity Information System (65 records of at least14 species), and the citizen science project Mediterranean Elasmobranchs Citizen Observations (117 records per 23 species). Our updated checklist reports 60 species that account for about 70% of the Mediterranean chondrichthyan biota. The list includes 15 more species than the previous checklist and our study reports three new species for Cyprus waters, namely the blackmouth catshark Dalatias licha, the round fantail stingray Taeniurops grabatus, and the sawback angelshark Squatina aculeata. Our research highlights the need for conservation measures and more studies regarding the highly threatened blackchin guitarfish Glaucostegus cemiculus and the devil ray Mobula mobular, and stresses the importance for training a new generation of observers to strengthen the knowledge and conservation of elasmobranchs in the region.

The presence of the great white shark (Carcharodon carcharias) in the Mediterranean Sea is well documented, but encounters with this species are rare and all assumptions about its spatial and temporal distribution are heavily relying on anecdotal observations. To date, only one record off the Libyan coast has been reported, raising the question if this species is underreported in these waters or simply represents a rare occasional transient. We utilised citizen science-sourced data to document the presence of the great white shark off the Libyan coast, and found six additional records for this species from the period between 2017 and 2020. Our study points out the need for scientific monitoring of this species along the Libyan coast to facilitate the establishment of effective conservation plans to protect this critically endangered species.

The Mediterranean Sea is an extinction hotspot for sharks, skates, and rays, with at least half of all species being threatened. The sandbar shark Carcharhinus plumbeus is among the most threatened species and is declared endangered (EN) in the Medi-terranean according to the IUCN Red List of Threatened Species. The Adriatic Sea was previously proposed to be an important nursery area for this species based on sporadic sightings of neonates and juveniles. However, this species is generally considered to be rare in this region, and reports of its presence are scarce. Here, we present new records for the sandbar shark in the Adriatic Sea and review spatial and temporal data accumulated from literature, museum specimens, and citizen science initiatives in an attempt to assess the distribution and seasonality of this species. The majority of the records were from neonate and juvenile sandbar sharks, and three hotspots for their occurrence could be identified: (1) the Emilia-Romagna region, (2) the Veneto region, and (3) the Gulf of Trieste. Our data indicate a high concentration of sandbar sharks around the delta of the Po river, emphasising the need for scientific surveys in this confined area in order to confirm a possible nursery ground. Data collected by citizen science initiatives reveal that this species is still present in the Adriatic Sea and might be more abundant than previously thought, underlining the potential of citizen science as a valuable tool to monitor the distribution of rare and endangered species.

Angel Sharks are among the most threatened families of fish in the world. In the Mediterranean three species are present facing a severe depletion with several local extinction events as a result of overexploitation by fisheries. Hereby, we present 7 additional records of Squatina squatina from Corsica contributing to the new regional action plan for Angel Sharks in the Mediterranean Sea. Most records include juvenile specimens, indicating that the area might be a nursery ground for the species.

Elasmobranchs, extremely charismatic and threatened animals, still are an important economic source for fshers in many parts of the world, providing signifcant income through trade. Even though Greek seas host at least 67 elasmobranch species, our knowledge about their biology and ecology is to a large extent unknown. In the present study the integration of conventional (legislation, offcial data from fsheries landings and fsh market value and import/export data) and unconventional (social media) sources of data, accompanied with the use of genetics, aim at outlining the elasmobranch fsheries and trade in Greece and identifying “weak spots” that sabotage their conservation. Results revealed that: (a) about 60% of the 68 specimens collected in fsh markets were mislabelled, with that being very common for Prionace glauca and Mustelus spp., (b) Illegal fshing is a reality, c) Greece represents one of the top-three European Union southern countries in terms of elasmobranch market size, (d) Aegean Sea and especially its Northern part (Thermaikos Gulf and Thracian Sea) contributed to more than half of the M. mustelus Greek fsheries landings and (e) wholesale prices of elasmobranchs have remained stable during the last decade. Mislabelling and illegal trade of elasmobranchs are common ground in Greece. This context stems from incoherent and complex fsheries legislative framework due to institutional decoupling, discrepancies in the collection and analysis of fsheries-related data, thus substantially reducing the effciency of the fsheries management in Greek seas.

1. All three species of angel sharks (genus Squatina) inhabiting the Mediterranean Sea are listed as Critically Endangered in the International Union for Conservation of Nature Red List of Threatened Species due to overexploitation. 2. New records from Cyprus, Greece, Italy and Libya were collected from citizenscientists and integrated with local knowledge obtained using structured interviews in the four countries. 3. Observations and reports, together with an analysis of the reconstructed fisheries data, resulted in the identification of areas of interest, a review of the illegal trade of the species and a debate about the credibility of fisheries data for assessing threatened and/or protected species. 4. Unconventional sources of information, such as social media, were identified as important tools for monitoring rare and endangered marine wildlife. 5. This work will contribute to promoting international cooperation for advancing angel shark conservation in line with the Eastern Atlantic and Mediterranean Angel Shark Conservation Strategy.

The spiny butterfly ray, Gymnura altavela (Linnaeus, 1758), is a species of ray, native to the Atlantic Ocean (including the Mediterranean), exhibiting a patchy distribution in tropical and subtropical areas in continental brackish waters in a depth range of 5 - 150 m(Weigmann, 2016). The Mediterranean population has been listed as Critically endangered in the latest IUCN Assessment while in the Greek Red Book is not evaluated due to lack of data. Accordingly, to its poor conservation status, the species is included in the Annex II of the Barcelona Convention and is currently protected via the Recommendation GFCM/42/2018/2 (amending GFCM/36/2012/3). Hereby we present additional records of this highly endangered species based on citizen science records and auction market observations.

The porbeagle (Lamna nasus) is a species of mackerel shark of the Lamnidae family distributed widely in the cold and temperate waters of the North Atlantic, as well as the Mediterranean Sea and the Southern Hemisphere. This species is considered Critically Endangered worldwide and in the Adriatic Sea, the occurrence of this vulnerable species is sporadic. In this work we aim to complement the existing occurrence list of porbeagles in the Adriatic Sea by adding an individual caught near Čiovo Island, the Channel of Split, by a professional fishing vessel.

The kitefin shark Dalatias licha is a deep sea shark rarely recorded in the eastern Mediterranean Sea, where it has been incidentally caught by deep waters long-lines and trawling. The present study concerns a female of 99 cm in total length stranded on a Greek coast (SE Ionian Sea). It was found severely decomposed. Basic morphological measures were recorded and its stomach was removed for diet examination. The current work provides for the first time valuable biological information on this rare deep sea shark and new records of prey preference in the Mediterranean Sea.

The alarming state of sharks and rays in the world and specifically in the Mediterranean Sea Is well known. In order to create effective conservation plans, basic ecological data such as distribution, and abundance are needed. For elasmobranchs, a large gap currently exists between the risk assessments and the basic ecological knowledge, though crucial in identifying important areas of high diversity, and keystone or endangered species. The MECO project aims to diminish this gap, by utilizing social media. Local scientists are searching the media, contacting the public and creating a large, verified database of elasmobranchs observations. Initial results from Israel and Greece revels differences in species composition and seasonality. Data collected from underwater observations yield species richness of 11 in Israel (1024 records) and 19 in Greece (80 records). While in Israel the species richness has remained constant for the last four years, in Greece it is still rising as the project runs for less than 2 years. The most common taxa in Israel were Dasyatis spp. (30%), Taenurops grabatus (25%) And Himantura spp. (16%). In Greece Dasyatis spp. comprised most observations (55%) followed by Gymnura altavela and Torpedo marmorata (7% each). The most observed species Dasyatis spp. showed a peak in observations in Israel around May-June followed by a smaller peak in October while In Greece the main season was June to August. Observations from fishermen and ports included additional deeper species, adding 9 species in Israel (128 records) and 20 in Greece (336 records). Hexanchus griseus was the most reported species in Greece and was observed throughout the year.