Mackerel Eggs Abundance Assessment: The aim of the international Mackerel and horse mackerel egg survey program is to estimate the spawning stock biomass (the total weight of all sexually mature fish in the population) of the North-east Atlantic mackerel and horse mackerel stocks. This data will feed into the stock assessment as fisheries independent information. In addition, the data provides important information on the timing and location of spawning for mackerel and horse mackerel. The survey has been running since 1977, taking place every three years, and therefore provides important information about the distribution and timing of spawning in relation to climate change. The Marine Institute participates in this programme and covers stations in the Celtic Sea. During this survey, plankton samples were collected at 112 stations, 11 fishing hauls were made to collect mackerel and horse mackerel samples for fecundity analysis. Samples were collected to ensure maximum temporal and geographical spread. CTDs (Conductivity-Temperature-Depth) were also carried out for the Oceanography section of the Marine Institute. This survey was conducted in the Celtic Sea and Southwest of Ireland, from 48N to 52.25N, and from 5W to 16W. This covered ICES areas VIIg, VIIh, VIIj and VIIk in march 2007 on board the R.V. Celtic Explorer. Fisheries survey into the abundance and distribution of Mackerel and Horse Mackerel.