Every three years the International Council for the Exploration of the Sea (ICES) coordinates a series of mackerel, Scomber scombrus, and horse mackerel, Trachurus trachurus, egg surveys covering the eastern Atlantic from Gibraltar to the north coast of Scotland between January and July. The aim of this survey programme is to estimate the spawning stock biomass of the northeastern Atlantic mackerel and horse mackerel stock. The Marine Institute participates in this programme and in this survey covered stations in the Celtic Sea. The survey, carried out in March 2010, took place in the Celtic Sea and Southwest of Ireland, from 48.75N to 51.75N, and from 6W to 17W. This covered ICES areas VIIg, VIIh, VIIj and VIIk. For operational reasons the survey was split in two. Leg 1 was conducted on board the Celtic Explorer from March 5th to 17th. This leg targeted the southern transects of the sampling area, and also carried out all the fishing tows. Leg 2 was carried out on the Celtic Voyager from March 19th to 29th and concentrated on the two northern transects of the area. At each station the GULF VII plankton sampler was towed. Fishing hauls were made using a herring pelagic net. The survey aims to collect egg and fecundity data for mackerel and horse mackerel for use in the 2010 stock assessments.