WGACEGG coordinates and provides quality control for acoustic and daily egg production (DEPM) surveys of several pelagic stocks in ICES areas 6-9.
During the 2023 meeting results from four DEPM surveys and nine acoustic surveys were pre-sented and discussed jointly with members of the Working Group on Southern Horse Mackerel, Anchovy, and Sardine (WGHANSA). The provided abundance estimates were considered relia-ble. However, given the increase in the distance between transects in the JUVENA acoustic sur-vey, its potential impact on the estimates was discussed. Anchovy stocks in areas 7 and 8 showed good conditions and continued evidence of northward migration. Sardine in area 9 was also in good condition due to last year’s recruitment, while horse mackerel and mackerel stocks were in generally poorer condition. Sprat biomass decreased in division 8 and increased in 7. Herring biomass in the western Channel is still under analysis, and boarfish stocks in divisions 6 and 7 are above average and increasing.
The group updated gridded maps and conducted space-time modeling of sardine distribution in the Bay of Biscay, showcasing the potential of common grid data.
The ICES TIMES report for DEPM surveys is under peer review. Preliminary discussion was held on future update of the ICES TIMES report for acoustics, improving the detail of the uncer-tainty estimates. Workshop sessions were held on both acoustic and DEPM databases.
Acoustic and egg-based biomass indices for anchovy and sardine available in area 8 were com-pared to evaluate their respective bias and precision. A workplan for investigating discrepancies between indices was proposed.
Methodological developments included a review of uncrewed vehicles for improved sampling, and improvements to surface school monitoring in acoustic surveys, based on lateral echosound-ers and multibeam sonars. Ongoing enhancements involved analyzing the ping interval's effect on acoustic abundance and a weakly supervised model for automatic classification of acoustic echotraces. A Bayesian approach to estimating egg production and mortality was introduced. Scientific studies covered evidence of anchovy's northward migration and a comparison of sar-dine genetics in Biscay and the English Channel.
WGACEGG members emphasized the importance of zooplankton monitoring, agreeing to host a Zooplankton Session in 2024 to address sampling and analysis methodologies for surface mes-ozooplankton communities.