European Ocean Biodiversity Information System

The Fixed Line Transect Mediterranean monitoring Network (FLT Med Net) is a multidisciplinary monitoring project coordinated by ISPRA since 2007, that uses ferry boats as observation platforms to undertake surveys of marine macro-fauna and main threats (maritime traffic and floating marine litter). The programme involves several partners (EcoOcean Institut, CIMA Research Foundation, University of Pisa, University of Tourin, Gaia Research Institute, Accademia del Leviatano, Capo Carbonara MPA, Ketos, University of Palermo, ATUTAX, University of Barcelona, University of Cadiz, Nereide) that share common protocols for data collection across different routes in the Mediterranean Sea. For cetaceans monitoring, data are collected by 2-3 dedicated observers (MMOs) placed on both sides of command deck of ferries during the entire trip, following standard line transect protocol. Observations are undertaken only in good weather conditions (Beaufort state <4). Each observer covers an angle of 130° from the bow. Back of the ship is checked only randomly to avoid double counting of sightings. In case of sighting, animals are not approached but distance and angle from the trackline are recorded, together with number of animals or group size estimation (minimum-maximum-best), presence of juveniles, behavior and response to the ship (escape-approach-indifferent). The dataset here provided consists of sighting data of marine mammals collected between January 2014 and December 2018, along the ferry route between Italy and Spain, crossing the Western Mediterranean Sea region: Tyrrhenian Sea, Sardinian Sea and Balearic Sea. The transect was surveyed all year round, in good weather conditions (Beaufort <4), covering more than 71.300 km over 291 transect lines. During the effort period, a total of 1432 georeferenced sightings of cetacean species were registered, of 8 identified species: Balaenoptera physalus, Physeter macrocephalus, Ziphius cavirostris,Tursiops truncatus, Stenella coeruleoalba, Delphinus delphis, Globicephala melas, Grampus griseus