COMMON WHELK Buccinum undatum
Publication of Advice: 6 June 2025. Published by Marine and Freshwater Research Institute.
Advice
MFRI advises in accordance with the MSY approach that catches in the fishing year 2025/2026 should be no more than 178 tonnes in Breiðafjörður.
Stock development
Fishing pressure is below Flim and FMSY. Stock biomass is above Blim and Btrigger.
Common whelk. Catches, changes in relative biomass (B/BMSY) and relative fishing mortality (F/FMSY). Shaded areas represent 95% CI.
Basis of the assessment and reference points
Basis of the advice | MSY approach |
Management plan | There is no management plan for this stock |
Assessment type | Surplus production model (SPiCT) |
Input data | Catch and standardized CPUE |
Approach | Reference point | Value | Basis |
|---|---|---|---|
MSY approach | MSY Btrigger | 0.5 | BMSY is estimated from surplus production model |
FMSY | 1.0 | Fishing mortality values expressed relative to FMSY | |
Precautionary approach | Blim | 0.3 | A fraction of BMSY where production is 50% of MSY |
Flim | 1.7 | Fishing mortality which results in median SSB at Blim |
The advice for 2025/2026 is lower than the advice for 2024/2025 because the biomass index has decreased.
Prospects
Common whelk. Assumptions made for the interim year and in the forecast.
Variable | Value | Notes |
|---|---|---|
Projected catch (2025) | 219 | Short term forecatch under Fsq; in tonnes |
Stock size B2026/BMSY (2026) | 0.82 | Short-term forecast at status quo F (Fsq); in tonnes |
Fishing mortality F2024/FMSY (2025) | 1 | Status quo F: F2024/FMSY |
Common whelk. Projection of biomass (tonnes) based on the MSY approach
Basis | Catch (2025/2026) | Fishing mortality (2026) | Stock size (2027) | % Biomass change | % Advice change |
|---|---|---|---|---|---|
MSY approach: FMSY | 178.2 | 0.76 | 0.84 | 1 | -6 |
Quality of the assessment
The assessment in 2025 is consistent with the previous assessments.
Common whelk Current assessment (red line) compared with two previous estimates.
Advice, tac and catch
Common whelk. Recommended TAC, national TAC, and catches (tonnes).
Fishing year | Recommended TAC | National TAC | Total catch |
|---|---|---|---|
2012/2013 | 750 | 269 | |
2013/2014 | 750 | 0 | |
2014/2015 | 750 | 166 | |
2015/2016 | 750 | 332 | |
2016/2017 | 750 | 186 | |
2017/2018 | 500 | 171 | |
2018/2019 | 500 | 324 | |
2019/2020 | 220 | 133 | |
2020/2021 | 264 | 88 | |
2021/2022 | 264 | 239 | |
2022/2023 | 254 | 268 | |
2023/2024 | 196 | 211 | |
2024/2025 | 190 | ||
2025/2026 | 178 |
References and further reading
Pedersen, M. W., & Berg, C. W. (2017). A stochastic surplus production model in continuous time. Fish and Fisheries, 18(2), 226-243.
ICES. 2025. ICES Guidelines - Advice rules for stocks in category 2 and 3. Version 3. ICES Guidelines and Policies - Advice Technical Guidelines. 31 pp. https://doi.org/10.17895/ices.pub.28506179
MFRI Assessment Reports 2025. Common whelk. Marine and Freshwater Research Institute, 6 June 2025.