Assessing the current status of Hexanchus griseus in the Mediterranean Sea using local ecological knowledge

Fishermen from 9 countries distributed throughout the Mediterranean Sea were interviewed between May and December 2019 with the aim of compiling information about the current impact of fisheries on a large deepwatershark species, the bluntnose sixgill shark (Hexanchus griseus). A total of 382 professional fishermenbelonging to 6 different gears (bottom trawling, bottom longline, drifting longline, trammel nets, gillnets andpolyvalent) took part in the study. Bottom trawlers were the most interviewed fishermen (n = 148) and the bestfleet coverage was obtained for bottom longline (38.89%). Results showed most captures of H. griseus occur in theWestern and Central Mediterranean Sea, particularly during the warm months of the year and most commonly bybottom trawlers and bottom longliners. At-vessel mortality (AVM) was rather low in all gears but a slightlyhigher degree of individual mortality is suggested in trammel and gillnets. The population trend of H. griseus inthe Mediterranean Sea could not be inferred from the interviews as answers were highly variable, but the overalltrend in some countries may suggest this species is showing signs of population decrease. The results of this studyare mostly aligned with the latest IUCN assessment but also recommend reviewing the current status of H. griseusin the Mediterranean basin. Further empirical research on post-release mortality would also be advisable toimplement measures that help reduce this source of mortality

Priorities for Mediterranean marine turtle conservation and management in the face of climate change

As climate-related impacts threaten marine biodiversity globally, it is important to adjust conservation efforts to mitigate the effects of climate change. Translating scientific knowledge into practical management, however, is often complicated due to resource, economic and policy constraints, generating a knowledge-action gap. To develop potential solutions for marine turtle conservation, we explored the perceptions of key actors across 18 countries in the Mediterranean. These actors evaluated their perceived relative importance of 19 adaptation and mitigation measures that could safeguard marine turtles from climate change. Of importance, despite differences in expertise, experience and focal country, the perceptions of researchers and management practitioners largely converged with respect to prioritizing adaptation and mitigation measures. Climate change was considered to have the greatest impacts on offspring sex ratios and suitable nesting sites. The most viable adaptation/mitigation measures were considered to be reducing other pressures that act in parallel to climate change. Ecological effectiveness represented a key determinant for implementing proposed measures, followed by practical applicability, financial cost, and societal cost. This convergence in opinions across actors likely reflects long-standing initiatives in the Mediterranean region towards supporting knowledge exchange in marine turtle conservation. Our results provide important guidance on how to prioritize measures that incorporate climate change in decision-making processes related to the current and future management and protection of marine turtles at the ocean-basin scale, and could be used to guide decisions in other regions globally. Importantly, this study demonstrates a successful example of how interactive processes can be used to fill the knowledge-action gap between research and management.This work was conducted under FutureMares EU project that received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 869300. The Mediterranean Marine Turtle Working Group was established in 2017 and is continuously supported by MedPAN and the National Marine Park of Zakynthos. The work of AC was supported by the Hellenic Foundation for Research and Innovation (H.F.R.I.) under the “First Call for H.F.R.I. Research Projects to support Faculty members and Researchers and the procurement of high-cost research equipment grant” (Project Number: 2340).Peer reviewe

MEDLEM database, a data collection on large Elasmobranchs in the Mediterranean and Black seas

The Mediterranean Large Elasmobranchs Monitoring (MEDLEM) database contains over 3000 records (more than 4000 individuals) of large elasmobranch species from 20 different countries around the Mediterranean and Black seas, observed from 1666 to 2017. The main species included in the archive are the devil fish (1 813 individuals), the basking shark (939 individuals), the blue shark (585 individuals) and the great white shark (337 individuals). In the last decades other species such as the shortfin mako (166 individuals), the spiny butterfly ray (138) and the thresher shark (174 individuals) were reported with an increasing frequency. This was possibly due to an increased public awareness on the conservation status of sharks, and a consequent development of new monitoring programmes. MEDLEM does not have a homogeneous reporting coverage throughout the Mediterranean and Black seas and it should be considered as a database of observed species presence. Scientific monitoring efforts in the south-eastern Mediterranean and Black seas are generally lower than in the northern sectors and the absence in our database of some species does not imply their actual absence in these regions. Some considerations are made on the frequency and spatial distribution of records, size structure of the observed individuals for selected species, general area coverage and species involved as by-catch by fishing gear