New technologies can support data collection on endangered shark species in the Mediterranean Sea

Abstract

In the last 50 yr, shark populations showed steep declines in the Mediterranean Sea. The IUCN lists most Mediterranean species as Endangered (55%), while considering 27.5% of them Data Deficient. Here, sharks are currently one of the rarest and more elusive groups of animals, and data from fisheries and scientific monitoring still insufficiently support robust abundance and distribution assessments. New technologies can fill this data gap by linking people and scientists through new monitoring strategies. SharkPulse, an international collaborative project, aims at creating a large world database of shark occurrence records by mining images on the web, social networks, and private archives. Here we analyzed 1186 sharkPulse records from the Mediterranean Sea. We collected records to characterize spatio-temporal patterns on 37 species, highlighting distribution changes for 5, and, by using generalized linear models, estimating trends in sighting for the most abundant species. With 273 records, Hexanchus griseus had the most sighting records since the beginning of the series. We identified pupping areas and aggregation sites for immature Prionace glauca and Isurus oxyrinchus; pinpointed strongholds of the Critically Endangered Squatina squatina to focus conservation efforts; and identified broader than previously reported regional distribution ranges for Alopias superciliosus, Dalatias licha, Heptranchias perlo, H. griseus, Oxynotus centrina, and P. glauca. We confirmed that fishing is still the major threat for Mediterranean sharks and call for a greater effort in controlling the emerging patterns with efficient conservation effort indexes. If properly standardized, opportunistic data can efficiently and cost-effectively advance our understanding of shark abundance, distribution, and conservation status.

Improved Baited Remote Underwater Video (BRUV) for 24 h Real-Time Monitoring of Pelagic and Demersal Marine Species from the Epipelagic Zone

“…The surface camera has provided data on pelagic surface species, such as blue sharks, improving our knowledge of their densities and the problem of by-catch in the area [22]. As all individuals were at least juvenile animals, our results show that the area seems not to be a pupping area for this species as shown by other recent studies in the Mediterranean [40]. It should also be noted that previously unobserved pelagic marine species have also been observed with the new system, such as the oceanic puffer (Lagocephalus lagocephalus).…”

Preliminary evidence of a potential reproductive aggregation area of the common stingray Dasyatis pastinaca (Linnaeus, 1758) (Chondrichthyes – Dasyatidae) in the Central Mediterranean Sea

“…This study reports on the first characterization of a potential reproductive area of the common stingray D. pastinaca in the Strait of Messina (Central Mediterranean Sea), an important migration route for several cartilaginous fishes with a high frequency of records of Critically Endangered species (Canese et al, 2011;Malara et al, 2021;Bargnesi et al, 2022). Here, we specifically refer to the definition of reproductive areas proposed by Hyde et al (2022) for elasmobranchs "…areas where a regular or predictable presence of mature sharks and rays has been recorded for mating, and/or where pregnant females aggregate".…”