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.

Northeast Atlantic Mackerel . This migratory stock is widely distributed throughout the Northeast Atlantic with significant fisheries in several ICES subareas. The assessment conducted in 2021 is an update assessment, based on the configuration agreed during the 2019 interbenchmark with updates to include sampling of the commercial catch, a recruitment index and tagging time series updated to 2020 and data from the 2021 IESSNS swept area survey.

No update to the egg survey based SSB index is available with the most recent survey carried out in 2019 and the next survey scheduled for 2022. Advice is given based on stock reference points which were updated during a management strategy evaluation carried out in 2020. Following a strong increase from 2007 to 2014, SSB has been declining although it remains above MSY Btrigger.

Fishing mortality has been below FMSY since 2015 but is rising and is just below FMSY in 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 2021 update assessment indicates that SSB is continuing to decrease from a maximum reached in 2017, with below average recruitment from 2017-19, although it remains above MSY Btrigger in 2021. Fishing mortality has been above FMSY since 2014 and is rising since 2019. There are indications in the most recent data of a moderate increase in recruitment in 2020-21.

Norwegian Spring Spawning Herring . This stock is migratory, spawning along the Norwegian coast and feeding throughout much of the Norwegian Sea. The 2021 update assessment is based on an implementation of the XSAM assessment model introduced following a benchmark in 2016. This years’ assessment is consistent with that from 2020 but indicates an increase in SSB in the most recent year due to the strong 2016 year-class, the size of which has been revised upwards by the assessment.

However, stock size is forecast to resume declining with weak recruitment since 2016, although the stock is predicted to remain above MSY Btrigger. 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, above average recruitments from 2014-2018 have contributed to a recent rise in SSB, albeit from a low level in 2017. As in previous years the assessment, whilst indicating the same trend as previous assessments rescales the absolute levels of SSB and F over the time series and the working group proposes that a benchmark be scheduled to address this.

SSB in 20201 is estimated to be just above Blim. 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. Although no 2020 survey index is available due to restricted survey coverage, a reduction in the index value is observed in 2019 and a length based indicator continues to indicate F is above FMSY in both 2019 and 2020.

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 2021 update assessment continues to show the indicator fluctuating without trend since 2010.

However, large uncertainties remain with regard to 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 up-grade of the assessment category.