Working Group on Widely Distributed Stocks (WGWIDE)

WGWIDE reports on the status and considerations for management of the Northeast Atlantic mackerel, blue whiting, Western and North Sea horse mackerel, Northeast Atlantic boarfish, Norwegian spring-spawning herring, striped red mullet (subareas 6, 8, and divisions 7.a–c, e–k and 9.a), and red gurnard (subareas 3, 4, 5, 6, 7, and 8) stocks.

2024 catch advice was drafted for all eight stocks. Benchmark assessments are proposed for 2025 for mackerel, herring, and striped red mullet while both horse mackerel stocks and boarfish are scheduled to be benchmarked in 2024.

Northeast Atlantic mackerel. This migratory stock is widely distributed throughout the Northeast Atlantic with significant fisheries in several ICES subareas. The assessment conducted in 2023 is an update assessment, based on the configuration agreed during the 2019 interbenchmark and incorporates updates to the commercial catch, tagging, swept-area, egg survey, and recruitment index dataseries. Advice is given based on stock reference points which were updated during a management strategy evaluation carried out in 2020. SSB has been declining since 2014 but is above MSY B_trigger in 2023. Fishing mortality has been increasing since 2016 and above F_MSY since 2021.

Blue whiting. This pelagic gadoid is widely distributed in the eastern part of the North Atlantic. The current assessment configuration (interbenchmark in 2016) uses preliminary catch and sampling data along with the acoustic survey data from the current year. The 2023 update assessment indicates that SSB is increasing following strong recent recruitment and is well above MSY B_trigger. Fishing mortality has been above F_MSY since 2014.

Norwegian spring-spawning herring. This stock is migratory, spawning along the Norwegian coast and feeding throughout much of the Norwegian Sea. The 2023 update assessment is based on an implementation of the XSAM assessment model introduced following a benchmark in 2016 and is consistent with the 2022 assessment. SSB has been declining since 2009, except for an increase in 2021 which was due to the strong 2016 year class entering the SSB. Fishing mortality has been above F_MSY since 2019. Recruitment since 2016 is estimated to be below average and SSB is forecast to fall below MSY B_trigger in 2024 and decrease further in 2025 even if the management plan is applied in 2024.

Western horse mackerel. The Western stock of horse mackerel is distributed throughout ICES subareas 4, 6, 7, 8, and 9. Following a benchmark in 2017, the stock is assessed using the Stock Synthesis (SS) integrated assessment model. Stock reference points were revised in 2019. Following a period of declining SSB, there has been a modest rise since 2017, albeit from a low level. The 2023 assessment indicates that SSB is below B_lim and will remain so in 2025, even under the scenario of zero catch in 2024. Based on the MSY approach, advice for 2024 is therefore for zero catch. The assessment has been displaying significant retrospective bias, but the 2023 assessment is consistent with the 2022 assessment.

North Sea horse mackerel. Catch advice for this stock is issued biennially on the basis of an assessment based on a combined index from groundfish surveys in the North Sea and the Channel. The 2023 value is an increase on the 2022 value for the exploitable stock. A length-based indicator continues to indicate that fishing mortality remains above F_MSY.

Northeast Atlantic boarfish. Boarfish is a small, pelagic, planktivorous, shoaling species found over much of the Northeast Atlantic shelf but primarily in ICES subareas 4, 6, 7, and 8. The directed fishery occurs primarily in the Celtic Sea and developed during the early 2000s, initially unregulated before the introduction of a TAC in 2011. The stock is assessed using an exploratory Bayesian surplus production model with catch and survey data from groundfish surveys and an acoustic survey. The current assessment indicates that, following a sharp decline after 2012, biomass has been increasing in recent years. The most recent acoustic surveys indicate a period of above-average recruitment in recent years. A length-based indicator indicates that fishing mortality is below F_MSY.

Northeast Atlantic red gurnard. This stock was first considered by WGWIDE in 2016 with advice issued biennially. The assessment was benchmarked in 2021 and a survey-based relative biomass indicator was developed. The 2023 update assessment continues to show the indicator fluctuating without trend since 2010. However, large uncertainties remain regarding landings data due to poor resolution at the species level and reported discarding levels vary widely.

Striped red mullet in Bay of Biscay, Southern Celtic Seas, Atlantic Iberian waters. No assessment is available for this stock and information on abundance and exploitation level is limited with advice given triennially on the basis of the precautionary approach. However, there are a number of research projects underway which will inform a future benchmark and potential upgrade of the assessment category.