Working Group on Mackerel and Horse Mackerel Egg Surveys (WGMEGS; outputs form 2022 meeting)

The Working Group on Mackerel and Horse Mackerel Egg Surveys (WGMEGS) is responsible for the planning, data collection, and data analysis of the ICES triennial mackerel and horse mackerel egg surveys. This report focuses on the execution of the mackerel and horse mackerel egg survey (MEGS) in 2022.

The results of the two 2021 online Workshops on Mackerel, Horse Mackerel and Hake Eggs Identification and Staging (WKMACHIS) and on Adult Egg Production Methods Parameters estimation in Mackerel and Horse Mackerel (WKAEPM) were discussed, with the subsequent enhancements and recommendations proposed during these workshops outlined in the workshop reports (ICES, 2022 a,b) and also incorporated into both of the WGMEGS manuals (ICES 2019a, b).

Although the broad planning of the 2022 survey was undertaken during the 2021 planning meet-ing and detailed in the WGMEGS 2021 report, the provisionally agreed plan required additional intersessional refinements. The settled plan for the 2022 survey has been included as an annex in the latest version of the WGMEGS Manual for the Mackerel and Horse Mackerel Egg Surveys (ICES SISP 6, 2019a).

In 2022, the survey once again faced significant challenges with regards to its ability to provide adequate geographical and temporal coverage given the limited vessel resources at our disposal. In 2022, Portugal, Spain (IEO and AZTI), Ireland, UK/Scotland, the Netherlands, Germany, the Faroe Islands, and Norway participated in the egg survey in the western and southern areas. Denmark and UK/England, with some additional assistance from Norway surveyed the North Sea as a single-pass DEPM survey. This is the first time in many years that all surveys have been completed in the same year.

In 2022, the survey was split into six sampling periods. The final period ended in late July. Waters west and southwest of Portugal were surveyed in period 2 only. The Cantabrian Sea was sampled in periods 3–5 while Biscay was sampled in periods 3 to 6. The Celtic Sea and waters west of the British Isles were sampled in periods 3 to 7, and the waters north and northwest of Britain towards Iceland and into the Norwegian Sea were sampled in periods 5 and 6.

Mackerel daily egg production was highest in period 5, (May), for the western component, while for the southern component the maximum spawning intensity was observed in period 3. Total mackerel egg production (provisional, southern and western component combined) was 1.64 * 10¹⁵. Provisional fecundity estimate was 1178 egg per gram female, resulting in an SSB index of 3.88 * 10⁶ tonnes.

For the Western stock of horse mackerel, highest mean daily egg production was estimated during June, period 6. Spawning was very low throughout all survey periods, with an obvious peak occurring in period 6. Total annual egg production for western Horse mackerel was 5.15 * 10¹⁴, almost a 300% increase on 2019.