Proposed North Sea and West of Scotland Megrim Fisheries Management Plan

Stock Assessment and MSY

Scientific Advice

The following evidence has been collated from the most recent ICES assessment working group report (ICES 2024)^[6] and the associated ICES stock annex.^[7]

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 fishing industry, may also be used.

ICES provides annual advice for Northern Shelf megrim in areas 4.a and 6.a. ICES advice is organised according to categories, ranging from 1 (the most information available) to 6 (the least). Northern Shelf megrim in areas 4.a and 6.a 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 management action. Northern Shelf megrim in area 6.b is a Category 2 stock, which means that a full stock assessment method with catch and survey data is used, but for which only relative trends-based outputs are used. This is also considered by ICES to represent MSY-based advice, and is only slightly less robust than a full Category 1 assessment. Note that the assessment for areas 4.a and 6.a also presents relative outputs but is nevertheless considered to be Category 1 by ICES.

Benchmark exercises are a tool used by ICES to peer-review and incorporate new science or evidence into the stock assessment process. They are part of the process which ensures that ICES advice is based on the best available scientific evidence. The megrim stock in areas 4.a and 6.a was the subject of an ICES benchmark assessment in 2012, and in area 6.b in 2021.

Assessment of evidence

As set out above, Northern Shelf megrim is a stock that has a high level of data available. On this basis, there is sufficient available scientific evidence for the relevant fisheries policy authorities to make annual MSY assessments for all three areas of both Northern Shelf megrim stocks.

Northern Shelf megrim stocks are currently being fished sustainably. As of 2024 (which is the date of the latest ICES advice used to inform this FMP), the spawning stock biomass (SSB) for Northern Shelf megrim in areas 4.a and 6.a was above a level capable of producing the MSY Btrigger. SSB has been above MSY Btrigger since the beginning of the assessment time-series (1985). Fishing pressure has been below the MSY level (FMSY) since 2002.

The SSB for megrim in area 6.b was above a level capable of producing the MSY Btrigger as of 2024 (which is the date of the latest ICES advice used to inform this FMP). SSB has been above MSY Btrigger since 2009. Fishing pressure has been below the MSY level (FMSY) since 2007.