There are currently nine nations and ten institutes participating in the survey, which has a geographical area that extends from Cadiz in the south to Icelandic waters in the north.
Data collected from both surveys provide an estimate of the total annual egg production that in turn provides an estimate of spawning-stock biomass for both the western and North Sea Atlantic mackerel stocks. It also provides a relative abundance index of spawning for horse mackerel in the Northeast Atlantic.
The surveys are divided into three geographical component areas: the western, southern and the North Sea. In the western area, the mackerel egg survey has been running continuously on a triennial basis since 1977 and since 1992 has also sampled the southern spawning component. It typically takes place between February and July and aims to cover the entire spawning area from Cadiz in the south to Northwest Scotland and since 2010, up to the waters around the Faroe Islands and southeast of Iceland. The egg survey in the North Sea has been running since 1968.
