Working Group on Widely Distributed Stocks

  

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. 

2023 catch advice was drafted for mackerel, Western horse mackerel, blue whiting and herring. For the remainder, multi-annual catch advice was previously published. Benchmark assessments are proposed for 2024 for mackerel, both horse mackerel stocks, herring and striped red mullet with boarfish is scheduled to be benchmarked in 2023. Prior to any benchmark assessment for mackerel, WGWIDE recommends that a workshop to review the latest knowledge with regard to the stock component structure takes place.

Northeast Atlantic Mackerel. This migratory stock is widely distributed throughout the North-east Atlantic with significant fisheries in several ICES subareas. The assessment conducted in 2022 is an update assessment, based on the configuration agreed during the 2019 inter-benchmark and incorporates updates to the commercial catch, tagging, swept area and egg sur-vey (preliminary) data series. No recruitment index is available for the 2021 year-class as survey coverage was inadequate. Advice is given based on stock reference points which were updated during a management strategy evaluation carried out in 2020. Following a decline since 2014, SSB has been stable (above MSY Btrigger) since 2019. Fishing mortality has been increasing since 2016 and is above FMSY since 2020.

Blue Whiting. This pelagic gadoid is widely distributed in the eastern part of the North Atlantic. The current assessment configuration (inter-benchmark in 2016) uses preliminary catch and sampling data along with the acoustic survey data from the current year. The 2022 update as-sessment indicates that SSB is increasing following strong recent recruitment and is well above MSY Btrigger. Fishing mortality has been above FMSY since 2014 but is falling.

Norwegian Spring Spawning Herring. This stock is migratory, spawning along the Norwegian coast and feeding throughout much of the Norwegian Sea. The 2022 update assessment is based on an implementation of the XSAM assessment model introduced following a benchmark in 2016 and is consistent with the 2021 assessment. Following a period of decline since 2009, SSB has been relatively stable just above MSY Btrigger in recent years, due to the strong 2016 year-class. However, recruitment since 2016 is estimated to be below average and the stock size is forecast to fall below MSY Btrigger 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 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 2022 assessment indicates that SSB is below Blim and will remain so in 2024, even under the scenario of zero catch in 2023. Based on the MSY approach, advice for 2024 is therefore for zero catch. The assessment continues to display significant retrospective issues which should be investigated by a benchmark 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. No survey index was available in 2020 due to restricted survey coverage, and the 2021 value is a reduction on the 2019 value for the exploitable stock. A length based indicator continues to indicate that fishing mortality remains above FMSY.

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 from 2018-2020.

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 2022 update assessment continues to show the indicator fluctuating without trend since 2010. However, large uncertainties remain with regard to land-ings 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 as-sessment 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.