Northern Shelf Blue Whiting Fisheries Management Plan

Stock Assessment and MSY

Scientific evidence

As set out in Section 3.2 of the JFS, the UK takes an evidence-based approach to fisheries management, making use of the best available scientific evidence. For the purpose of stock management and TAC setting, this tends to focus on the use of advice produced by ICES, although other sources of information, including data from the pelagic fishing industry via the co-sampling programme, may also be used.

ICES provides annual catch advice for blue whiting. Different models are used for assessment and advice, depending on availability and quality of data and uncertainty. The type of assessment is categorised from 1 (quantitative/analytical) to 6 (bycatch only data). The advice type is then given based on MSY principles, including data limited approaches (MSY proxy), and/or following a precautionary approach. Blue whiting is a Category 1 stock, which means that it is considered to have full age- and size-structured data on which to base an assessment, and that MSY reference points are available to provide a framework for advice on sustainable management.

Benchmark exercises are a tool used by ICES to evaluate existing and new scientific evidence and methods and, where relevant, apply them in the stock assessment process. They are part of the continuous improvement process which ensures that ICES advice is based on the best available scientific evidence. ICES completed an assessment benchmarking process for Northern Shelf blue whiting in 2016, with the next benchmark due to take place in 2027.

Assessment of evidence

The following evidence has been collated from the most recent ICES assessment working group report (ICES 2024)^[7].

As set out above, blue whiting is a stock that has a high volume of data available. On this basis, there is sufficient available scientific evidence for the relevant fisheries policy authorities to make annual MSY assessments of the blue whiting stock.

Recruitment of blue whiting is irregular, with sporadic years of very good recruitment interspersed by periods of low recruitment. As a result, biomass fluctuates significantly. Recruitment (age 1) was at a historical high from 2021 to 2022, although it has since dropped back to more normal levels. Spawning Stock Biomass (SSB) was on an upward trend between 2022 and 2024, although decreased in 2025. SSB has, however, remained above MSY B_trigger since 1997. At the time of writing this FMP, fishing pressure is above F_msy. This is largely due to the lack of a quota sharing arrangement between the relevant coastal States.

Since 2021, the Long-Term Management Strategy (LTMS) for blue whiting^[8] agreed between the UK, EU, Faroe Islands, Iceland, and Norway underpins the catch advice, assessment and wider evidence on the stock. Since 2018, catch advice over this time period has fluctuated between 0.75 and 1.5 million tonnes. ICES also provide the catch corresponding to the MSY approach as an alternative scenario.