*Corresponding author: anamafaldacorreia@gmail.com | ORCID: 0000-0003-4781-6894 Running head: Common dolphin distribution in the Eastern North Atlantic 1 2 Distribution and habitat modelling of common dolphins (Delphinus delphis) in the 3 Eastern North Atlantic 4 Ana M. Correia 1,2, *, Ágatha Gil 1,2 , Raul Valente 1,2 , Massimiliano Rosso 1,3 , Graham J. Pierce 4,5,6 , Isabel Sousa-Pinto 1,2 5 1 Interdisciplinary Centre of Marine and Environmental Research (CIIMAR). 4450-208 Matosinhos, Portugal. 6 2 Department of Biology, Faculty of Sciences, University of Porto (FCUP). 4169-007 Porto, Portugal. 7 3 CIMA Research Foundation. 17100 Savona, Italy. 8 4 Instituto de Investigacións Mariñas (CSIC). 36208 Vigo, Pontevedra, Spain. 9 5 Oceanlab, University of Aberdeen. AB41 6AA, UK. 10 6 CESAM and Department of Biology, University of Aveiro. 3810-193 Aveiro, Portugal. 11 12 Abstract 13 The Eastern North Atlantic (ENA) has many highly productive areas where several species of 14 cetaceans have been recorded, with the common dolphin (Delphinus delphis) being one of the 15 most frequently sighted species. However, its spatial and temporal distribution in high seas is 16 poorly known. The study presents the results from 5 years of cetacean monitoring in the ENA 17 (2012-2016) aboard cargo ships that follow the routes from the Continental Portugal to the 18 Macaronesian archipelagos and the Northwest Africa. Common dolphin was the most 19 frequently sighted cetacean with 192 occurrences registered on effort and an overall encounter 20 rate of 0.36 sightings / 100 nmi. The species was distributed in coastal and offshore waters, but 21 absent from Canaries and Cape Verde islands. Statistical “habitat” models were developed to 22 describe and explain the occurrence of sightings of the species: variables affecting detection of 23 dolphins had a small impact and there were clear spatiotemporal distribution patterns, 24 influenced to some degree by environmental variables. Predicted probability of occurrence was 25 highest in coastal waters of continental Portugal and around the Azores. The models, combined 26 with maps of distribution, were useful to identify important areas for the species, which could 27 be the focus of future conservation efforts. Common dolphin presence was related to depth, 28 distance to coast and seamounts, seabed slope, chlorophyll concentration, sea-surface 29 temperature and sea level anomalies; the possible ecological significance of these relationships 30 is explored. 31 32 Keywords: cetaceans; Macaronesia; high seas; spatial distribution; temporal distribution; 33 ecological modelling 34