Climate-induced changes in sea surface temperature, phytoplankton biomass and the North Atlantic Oscillation (NAO) have been suggested as causes of several long-term declines or shifts in phytoplankton and copepods in the North Atlantic, which in turn may affect higher trophic levels. Krill are key species in the North Atlantic, serving as food for many marine animals as several fishes, marine mammals and sea birds. The aim of this study was on use data on euphausiid abundance collected by the Continuous Plankton Recorder (CPR) survey, to investigate the impacts of climate change on euphausiid abundance in the North Atlantic from 1958 to 2007. Sea surface temperature, sea surface salinity, NAO, surface Chlorophyll a concentrations and timing of the spring bloom were used as explanatory variables. On a spatial scale, the annual mean krill numbers gradually decreased from east of Greenland (Irminger Sea) to west of Faroe Islands, indicating that the Irminger Sea may serve as a high productive area or population centre of krill in the North Atlantic. On a temporal scale, a general and significant decreasing trend in yearly mean euphausiid numbers since the early 1980s was indicated. The drivers for the observed changes vary geographically. In the western area, the changes are mainly attributed to bottom-up effects of phytoplankton growth and development, while in the eastern areas sea surface temperature is more important.