Working Group on Mackerel and Horse Mackerel Egg Surveys (WGMEGS)

The ICES Working Group on Mackerel and Horse Mackerel Egg Surveys (WGMEGS) met in 2024, to plan the 2025 Mackerel and Horse Mackerel Egg Survey. The nations participating in the 2025 MEGS survey are Germany, Ireland, Netherlands, Scotland, Spain, Faroe Islands, Norway, England and Denmark. Portugal have yet to confirm their participation.

In 2025, the MEGS survey will continue as an AEPM survey. However, as with the previous four surveys, the intention is to also carry out intensive DEPM sampling during expected peak spawning periods of both species in an attempt to calculate a DEPM SSB estimate. The periods highlighted as being the likely peak spawning periods are periods 3 and 4 for mackerel, and periods 6 and 7 for western horse mackerel.

The 2025 survey has been planned on six regular sampling periods. However, if Portugal is unable to conduct their DEPM survey for southern horse mackerel, there will only be five survey periods. The survey plan will be further refined in 2024 and an updated survey plan will be presented after the two workshops, to be held in the autumn: Workshop on Mackerel, Horse Mackerel and Hake Egg Identification and Staging (WKMACHIS2) and Workshop on Adult Egg Production Methods Parameters estimation in mackerel and horse mackerel (WKAEPM2). These workshops are essential for maintaining the quality assurance of the mackerel and horse mackerel egg surveys and it is strongly advised that participating analysts attend.

The revision and update work on the manuals started at the WGMEGS meeting and will be finalised in the planned workshops. The recommendation from WKMADE (2023, in prep.) in relation to batch size and uploading guidelines were included in the manuals and be implemented during the survey 2025. A Teams group was created to further work as a network during laboratory processing period.

The egg and larvae database is ready for use, although some errors need to be corrected in the future. The fecundity database is making good progress and certain decisions have been made in relation to the subsampleSize and subsampleVolume that will be included in the database at the sample level.