This dataset gathers, total abundance, abundance per size class, total biomass and biomass per size class of two vulnerable fish species, the dusky grouper, Epinephelus marginatus (Lowe, 1834), and the brown meagre, Sciaena umbra Linaeus, 1758, recorded inside and outside the Marine Natural Reserve of Scandola (Corsica, NW Mediterranean) in 2012 and 2018. Fish were recorded by underwater visual censuses performed on belt transects (50 x 15 m) run parallel to the coast between 1 and 40 m depth at 13 sites according to three levels of protection status (integral reserve, buffer zone and unprotected zone). A total of 532 transects were performed in 2012 and 526 in 2018. Image Reference: https://www.seanoe.org/data/00754/86639/illustrations/illustration-134.gif. Corsica 2012-2018-Map Scandola Marine natural Reserve Important Note: This submission has been initially submitted to SEA scieNtific Open data Edition (SEANOE) publication service and received the recorded DOI. The metadata elements have been further processed (refined) in EMODnet Ingestion Service in order to conform with the Data Submission Service specifications.

The ClimateFish database collates abundance data of 15 fish species proposed as candidate indicators of climate change in the Mediterranean Sea. An initial group of eight Mediterranean indigenous species (Epinephelus marginatus, Thalassoma pavo, Sparisoma cretense, Coris julis, Sarpa salpa, Serranus scriba, Serranus cabrilla and Caranx crysos) with wide distribution, responsiveness to temperature conditions and easy identification were selected by a network of Mediterranean scientists joined under the CIESM programme ‘Tropical Signals’ (https://www.ciesm.org/marine/programs/tropicalization.htm; Azzurro et al. 2010). Soon after, and thanks to the discussion with other expert groups and projects, C. crysos was no longer considered, and Lessepsian fishes (Red Sea species entering the Mediterranean through the Suez Canal) were included, namely: Fistularia commersonii, Siganus luridus, Siganus rivulatus, Pterois miles, Stephanolopis diaspros, Parupeneus forskali, Pempheris rhomboidea and Torquigener flavimaculosus. Considering the trend of increase of these species in the Mediterranean Sea (Golani et al. 2021) and their projected distribution according to climate change scenarios (D’Amen and Azzurro, 2020), more data on these tropical invaders are expected to come in the future implementation of the study. Data were collected according to a simplified visual census methodology (Garrabou et al. 2019) along standard transects of five minutes performed at a constant speed of 10m/min, corresponding approximately to an area of 50x5m. Four different depth layers were surveyed:  0-3m, 5-10 m, 11-20 m, 21-30 m. So far, the ClimateFish database includes fish counts collected along 3142 transects carried out in seven Mediterranean countries between 2009 and 2021, for a total number of 101'771 observed individuals belonging to the 15 fish species. Data were collected by a large team of researchers which joined in a common monitoring strategy supported by different international projects, which are acknowledged below. This database, when associated with climate data, offers new opportunities to investigate spatio-temporal effects of climate change in the Mediterranean Sea and test the effectiveness of each species as a possible climate change indicator.   Contacts: ernesto.azzurro(at)cnr.it   References: Azzurro E., Maynou F., Moschella P. (2010). A simplified visual census methodology to detect variability trends of coastal mediterranean fishes under climate change scenarios. Rapp. Comm. int. Mer Médit., 39. D’Amen, M. and Azzurro, E. (2020). Lessepsian fish invasion in Mediterranean marine protected areas: a risk assessment under climate change scenarios. ICES Journal of Marine Science, 77(1), pp.388-397. Garrabou, J., Bensoussan, N., Azzurro, E. (2019). Monitoring climate-related responses in Mediterranean marine protected areas and beyond: five standard protocols. Golani D.,  Azzurro E.,  Dulcic J.,  Massutí E., Orsi-Relini L.  (2021).  Atlas of Exotic Fishes in the Mediterranean Sea.  2nd edition  [F. Briand, Ed.]  365 pages.  CIESM Publishers, Paris, Monaco. ISBN number  978-92-990003-5-9    Important Note: This submission has been initially submitted to SEA scieNtific Open data Edition (SEANOE) publication service and received the recorded DOI. The metadata elements have been further processed (refined) in EMODnet Ingestion Service in order to conform with the Data Submission Service specifications.

The main purpose of this sampling was to study the effects of the OWEZ windpark on the demersal fish community. Because before installation of the windfarm the main fisheries activity in the area was bottom trawling, it is expected that exclusion of fisheries in the wind farm has the largest effect on the demersal fish community. The wind farm and its safety zone could function as a refugium for these species. If the area functions as a refugium this could be the case for a large number of demersal fish species that occur in the Dutch coastal zone. Owing to this a positive effect of the wind farm on the demersal fish community was expected. The fisheries that occurred in the area targeted larger fish, therefore fisheries mortality was higher on the larger fish. By excluding fisheries in the farm it was expected to change the size distribution in the farm and by that the age distribution of the fish populations. A Hydrolab minisonde, attached to the net, was used for continuous CTD measurements.