North Sea Herring 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 Total Allowable Catch (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 advice for NSAS herring. 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 ApproachI NSAS herring 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 process 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 interbenchmarking process for NSAS herring in 2021, and reference points were updated in 2024 and 2025. ^[5]

In addition, a Management Strategy Evaluation (MSE) process has also been undertaken by ICES. This was conducted 2024-2025 at the request of the trilateral parties managing the NSAS stock (UK, EU and Norway) to support the development of a robust long‑term management strategy (LTMS) for NSAS herring. This work drew on updated stock assessment models and a range of possible future scenarios. The MSE tested the performance of alternative harvest control rules (HCR) against management objectives, specifically yield, stability of catches and risk of stock depletion.^[6]

Assessment of evidence

The following evidence has been collated from the most recent ICES assessment working group report (ICES 2026)^[7].

As set out above, NSAS herring have a high level of data available overall. On this basis, there is sufficient available scientific evidence for the relevant fisheries policy authorities to make annual MSY assessments of the stocks. The data are available for the ICES Herring Assessment Working Group (HAWG) to make annual assessments of the stock status and provide advice on sustainable catches using the trilateral parties’ agreed LTMS, as described further below.

The most recent assessment released by the ICES Herring Assessment Working Group (HAWG) show that fishing pressure on the NSAS herring stock is below F_MSY, and the spawning stock size is above MSY B_trigger, B_PA, and B_lim.