Marine mammal and seabird observation survey led by Galway-Mayo Institute of Technology (GMIT) in 2016 on board the Celtic Explorer. This survey is part of an annual survey - Cetaceans on the Frontier. ‘Cetaceans on the Frontier’ has become an annual research cruise, lead jointly by the Galway-Mayo Institute of Technology (GMIT) and the Irish Whale and Dolphin Group (IWDG) which aims to record abundances and distribution of cetaceans along the continental shelf edge. The survey consisted of 5 dedicated survey blocks for marine mammal and seabird surveys located off the south coast of Ireland between Wexford and Cork. Surveying these allow for comparative analysis with similar surveys conducted here in 2012 during CV12029. Surveys took place between 1st and 7th December during daylight hours between 8:30am and 4:30pm (light and weather permitting). Each survey block consisted of 6 parallel transect lines of 7 nautical mile length each with a 1 nautical mile spacing in between. Dedicated surveying for marine mammals and seabirds took place on each of these transect lines with additional survey effort also carried out during transit between survey blocks. Marine mammal observations: Observer effort was focused on a 90 degree arc ahead of the ship. Sightings up to 90 degrees to port and starboard or coincidental sightings behind the boat are recorded as well. The observer scans the area systematically by eye and using binoculars. Surveying is conducted up to Beaufort sea-state 6 and in visibility = 500m. Bearings to sightings are measured using an angle board and distances are estimated with the aid of a range finder. Seabird observations: conducted visual surveys. Bird observations follow the European Seabirds At Sea (ESAS) proposed methods. All birds, flying or sitting on the water, are recorded within 90 degrees on either side of the boat in 1 min time blocks. Binoculars are only used to confirm species identity. Distance to the boat is estimated with a Heinemann range finder. 1. Conduct a visual survey using distance sampling techniques to calculate the abundance, density and distribution of marine mammals and seabirds in the Celtic Sea 2. Examine the temporal and spatial distribution of these animals in relation to key prey forage fish species, namely sprat and herring 3. Examine the temporal and spatial distribution of these animals in relation to other oceanographic processes (sea surface temperature, bathymetry, wind etc.) using data collected by remote sensing techniques 4. Obtain, when possible, photographic images of large baleen whales (humpback and fin) to add to an existing photo-ID catalogue 5. Conduct a visual survey for surface marine litter to calculate the its abundance, density and distribution in the Celtic Sea