Atlantic Herring in 6aS/7b, Industry Acoustic Survey Cruise Report, November-December 2023 and January 2024.

An acoustic survey of Atlantic herring Clupea harengus was conducted in ICES areas 6aS/7b in November/December 2023 and January 2024. This was the eight consecutive annual survey of herring in this area at this time of the year. The survey is part of an effort to describe the more dominant winter spawning herring in this area when it is geographically separated from other stocks. The survey design has been evolving since its inception in 2016. The survey area covered in the first 3 years (2016-18) included significant offshore coverage in areas 6aS and 7b. The survey in 2019 was much reduced and mostly confined to inshore bays because of poor weather. In 2020, the survey design changed compared with previous years in that only 6 core areas with prior knowledge of herring distribution from the monitoring fishery were targeted for surveying. This design was continued in 2021, 2022 and 2023. The change in survey design was largely based on results from the ICES workshop WKHASS held in 2019 (ICES 2020), and from lessons learned in the previous surveys in this area from 2016- 2019. The design results in a reduced survey area compared to earlier years, but there is more intense coverage of most of the important inshore bays where the monitoring fishery takes place. The survey design objective remains the same; to describe and quantify the distribution of winter spawning herring in the 6aS/7b area when separate from other stocks. The timing of surveys in the core areas was flexible from the outset by design in 2023. It was decided that greater flexibility would allow for a targeted spatial and temporal approach which avoided the inevitable poor weather that can happen in this area during this time of the year and which lead to reduced survey effort in 2019, but also to some extent in 2017 and 2018. Using smaller vessels allowed surveys to be conducted in shallow inshore areas where herring are known to inhabit during this time of the year. The previous surveys in 2016 - 2022 are reported in O’Malley et al (2017, 2018, 2019, 2020, 2021, 2022 and 2023).

URI

http://hdl.handle.net/10793/1983

Citation

O’Malley, M., Mullins, E., & Nolan, C. (2024). Atlantic Herring in 6aS/7b, Industry Acoustic Survey Cruise Report, November-December 2023 and January 2024. FEAS Survey Series: Industry Acoustic Survey/01/2023. Marine Institute, Ireland