European Ocean Biodiversity Information System

Original provider and dataset credits: Asociación de Naturalistas del Sureste (ANSE).Abstract: Marine megafauna visual surveys from a dedicated research vessel in the southeastern Spanish Mediterranean coast (Western Mediterranean Sea) from 2014 onwards (except for 2024 and 2025 when there were no campaigns). The dataset includes 13,887 occurrence records of seabirds, migratory birds, marine turtles, epipelagic fish, and jellyfish. The samplings were made following linear transects using Distance Sampling methodology (Buckland et al. 1993), with constant vessel speed at 5-6 knots and two observers covering a 180° observation arc (one portside, one starboard). Primary observation method was naked eye, supplemented with 8x40 binoculars for species identification. For each sighting, the following data were recorded: species, distance, angle, total number of individuals, age class (for birds: adult, immature, juvenile), behaviour (feeding, traveling, resting, foraging, kleptoparasiting, kleptoparasited, scavenging), and flight heading (when applicable).The dataset integrates observations from multiple conservation and monitoring projects conducted by ANSE in the region, including "Acuicultura y delfines" (2014), "Delfín mular y calderón gris en LIC marinos de Murcia y Andalucía" (2014-2016), "Guardians of The Sea" (2016), "Étude comportementale des capacités chimio-sensorielles des cétacés" (2017), "Caracterización de la Basura Marina en el LIC Valles Submarinos del Escarpe de Mazarrón" (2017-2018), CDMAPAMP (2019), INDELPESUR (2021), GlobAlGoVe (2020-2022), and "Conservación de calderón común en el sureste" (2023). This dataset contributes to the knowledge of marine megafauna distribution and behaviour in the Western Mediterranean and supports marine conservation efforts in the region.