Dab Limanda limanda
Publication of Advice: 6 June 2025. Published by Marine and Freshwater Research Institute.
Advice
MFRI advises that when the MSY approach is applied, catches in each of the fishing years 2025/2026 and 2026/2027 should be no more than 253 tonnes.
Stock development
Stock size at Itrigger and the fishing pressure is below FMSY proxy.
Dab. Catches, IS-SMB juvenile index (<21 cm), fishing pressure proxy and IS-SMB biomass (≥25 cm) index. IS-SMB juvenile index: the error bars show 95% confidence intervals. IS-SMB biomass index: the red horizontal lines indicate average biomass indices for 2021–2023 and for 2024–2025 used in the advice calculations; the shaded area shows 95% confidence intervals.
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 | Trends in biomass indicators |
Input data | Commercial catch and survey biomass indices (IS-SMB) |
Approach | Reference point | Value | Basis |
|---|---|---|---|
MSY approach | Itrigger | 1 540 | Iloss×1.4, Iloss defined as the lowest survey value |
FMSY_proxy | 1 | Relative value from LBI analysis, assuming M/K = 1.5. | |
Lc | 26 | Length at first capture, 50% modal abundance from catch length data | |
LInf | 47 | Asymptotic length, defined as maximum length from catch length data | |
K | 0.3 | Population growth rate | |
LF=M | 31.25 | 0.75 x Lc + 0.25 x LInf |
Prospects
The ICES framework for category 3 stocks, for which analytical assessment is not possible but trends in biomass indicators are assumed to reflect changes in stock dynamics, was applied (ICES, 2025). IS-SMB biomass index of dab ≥25 cm is used as an indicator of stock development. As sufficient data on life history in addition to length measurements from catches, the advice is based on the rfb-rule for ICES category 3 data-limited stocks and is valid for each of the fishing years 2025/2026 and 2026/2027.
Dab. Advice calculation.
Ay: Catch advice for 2024/2025 | 361 |
Stock biomass trend | |
Index A (2024-2025) | 1 871 |
Index B (2021-2023) | 3 133 |
r: Stock biomass trend (index ratio A/B) | 0.597 |
Fishing pressure proxy | |
Mean catch length (Lmean = L2024) | 33 |
MSY proxy length (LF=M) | 31 |
f: Fishing pressure proxy (LF=M/Lmean) | 0.934 |
Biomass safeguard | |
Last index value (I2025) | 1 595 |
Index trigger value (Itrigger=Iloss*1.4) | 1 540 |
b: Index relative to trigger value, min{I2025/Itrigger, 1} | 1 |
Precautionary multiplier to maintain biomass above Blim with 95% probability | |
m: Multiplier (generic multiplier based on life history) | 0.9 |
Advice calculation1) | 208 |
Stability clause (+20% / -30% compared to Ay, only applied if b>1)2) | 1 |
Catch advice for 2025/2026 and 2026/2027 | 253 |
% advice change3) | -30 |
1) Ay × r × 1/f × b × m | |
2) min{max(0.7Ay, Ay+1), 1.2Ay} | |
3) The figures in the table are rounded. Calculations were done with unrounded inputs, and compared values may not match exactly when calculated using the rounded figures in the table. | |
The advice for each of the fishing years 2025/2026 and 2026/2027 is lower than the advice for 2024/2025 because the stock size indicator has decreased.
Quality of the assessment
The recruitment index from the IS-SMB survey is considered inadequate for assessing recruitment, as the survey does not cover the main nursery areas located in shallow waters.
Other information
Stock indices for dab have remained low over an extended period and are at the Itrigger level this year. Recruitment has been poor since 2015, and there is considerable uncertainty regarding the strength of incoming year classes. In addition, there are indications of substantial overfishing. Taken together, these factors strongly suggest that the stock is in decline and may even have collapsed.
Advice, tac and catch
Dab. Recommended TAC, national TAC, and landings (tonnes)
Fishing year | Recommended TAC | National TAC | Total catch |
|---|---|---|---|
1995/1996 | 7 000 | 6 792 | |
1996/1997 | 7 000 | 8 283 | |
1997/1998 | 7 000 | 7 000 | 6 363 |
1998/1999 | 7 000 | 7 000 | 4 507 |
1999/2000 | 7 000 | 7 000 | 3 165 |
2000/2001 | 4 000 | 5 500 | 2 938 |
2001/2002 | 4 000 | 4 000 | 4 183 |
2002/2003 | 7 000 | 7 000 | 4 657 |
2003/2004 | 7 000 | 7 000 | 3 991 |
2004/2005 | 5 000 | 5 000 | 2 881 |
2005/2006 | 2 500 | 4 000 | 1 373 |
2006/2007 | 1 000 | 2 000 | 1 014 |
2007/2008 | 500 | 1 500 | 710 |
2008/2009 | 500 | 1 000 | 811 |
2009/2010 | 500 | 1 000 | 719 |
2010/2011 | 500 | 900 | 814 |
2011/2012 | 500 | 900 | 891 |
2012/2013 | 500 | 800 | 772 |
2013/2014 | 500 | 500 | 593 |
2014/2015 | 1 000 | 1 000 | 546 |
2015/2016 | 500 | 500 | 443 |
2016/2017 | 500 | 500 | 208 |
2017/2018 | 500 | 500 | 399 |
2018/2019 | 500 | 500 | 451 |
2019/2020 | 399 | 399 | 436 |
2020/2021 | 319 | 319 | 587 |
2021/2022 | 313 | 313 | 716 |
2022/2023 | 301 | 301 | 750 |
2023/2024 | 361 | 361 | 724 |
2024/2025 | 361 | 361 | |
2025/2026 | 253 | ||
2026/2027 | 253 |
References and further reading
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. Dab. Marine and Freshwater Research Institute, 6 June 2025.