COMMON WHELK Buccinum undatum
Publication of Advice: 12th June 2026. Published by Marine and Freshwater Research Institute.
Advice
MFRI advises in accordance with the MSY approach that catches in the fishing year 2026/2027 should be no more than 189 tonnes in Breiðafjörður.
Stock development
Fishing pressure is below FMSY and Flim. Stock biomass is above MSY Btrigger and Blim.
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 | A fraction of BMSY where production is 50% of MSY |
FMSY | 1 | Fishing mortality values expressed relative to FMSY | |
Precautionary approach | Blim | 0.3 | A fraction of BMSY where production is 30% of MSY |
Flim | 1.7 | Fishing mortality which results in median SSB at Blim |
Prospects
Common whelk. Assumptions made for the interim year and in the forecast.
Variable | Value | Notes |
|---|---|---|
Projected catch (2026) | 173 | Short term forecast under Fsq; in tonnes |
Stock size B2027/BMSY (2027) | 0.87 | Short-term forecast at status quo F (Fsq) |
Fishing mortality F2025/FMSY (2026) | 0.64 | Status quo F: F2025/FMSY |
Common whelk. Projection of biomass (tonnes) based on the MSY approach
Basis | Catch (2026/2027) | Fishing mortality (2027) | Stock size (2028) | % Biomass change1) | % Advice change2) |
|---|---|---|---|---|---|
MSY approach: FMSY | 189 | 0.64 | 0.88 | 1 | 6 |
1) Stock size in 2028 relative to stock size in 2027 | |||||
2) Advice value for 2027/2026 relative to advice value for 2026/2025 (178 t) | |||||
The advice for 2026/2027 is higher than the advice for 2025/2026 because the biomass index has increased.
Quality of the assessment
The assessment in 2026 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 | 239 | |
2025/2026 | 178 | ||
2026/2027 | 189 |
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 2026. Common whelk. Marine and Freshwater Research Institute, 12 June 2026.