BLUE LING Molva dipterygia
Publication of Advice: 7. june 2024. Published by Marine and Freshwater Research Institute.
Advice
MFRI and ICES advises that when the MSY approach is applied, catches in each of the fishing years 1 September 2024 to 2025 and 1 September 2025 to 31 August 2026 should be no more than 307 tonnes. Additionally, the MFRI advises that spawning areas south of Vestmannaeyjar and Franshóll be closed to all fishing activities during spawning season (15 February–30 April).
Stock development
Stock size is above MSY Btrigger_proxy (Itrigger), and the fishing pressure is belove FMSY_proxy
Blue ling Catch by gear types, index in abundance of < 40 cm fish, Length based fishing pressure proxy (LF=M/Lmean) which is used for the evaluation of the exploitation status. The proxy fishing pressure is less than that corresponding to the FMSY proxy when the value is lower than 1, and Biomass index of ≥ 40 cm fish. Shaded areas and error bars show 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-SMH) |
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. IS-SMH is used as biomass indicator. Information on life-history parameters is available and length data are sufficient and thus, the assessment is based on the new rfb-rule for ICES category 3 data-limited stocks (ICES 2021).
Approach | Reference point | Value | Basis |
|---|---|---|---|
MSY approach | Itrigger | 0.8 | Iloss×1.4; Iloss defined as the lowest survey value (2000) |
FMSY_proxy | 1.0 | Relative value from LBI analysis, assuming M/K = 1.5. LF = M is based on Lc (length at 50% of modal abundance), which varies each year |
Blue ling. Advice calculations.
Ay: Catch advice for 2023/2024 | 259 |
Stock biomass trend | |
Index A (2022-2023) | 1 058 |
Index B (2019-2021) | 862 |
r: Stock biomass trend (index ratio A/B) | 1.226 |
Fishing pressure proxy | |
Mean catch length (Lmean = L2023) | 97 |
MSY proxy length (LF=M) | 95 |
f: Fishing pressure proxy (L2023/LF=M) | 1.019 |
Fishing pressure proxy relative to MSY proxy (LF=M/L2023) | 0.98 |
Biomass safeguard | |
Last index value (I2023) | 1 420 |
Index trigger value (Itrigger=Iloss*1.4) | 804 |
b: Index relative to trigger value, min{I2024/Itrigger, 1} | 1 |
Precautionary multiplier to maintain biomass above Blim with 95% probability | |
m: Multiplier (generic multiplier based on life history) | 0.95 |
Advice calculation | 307 |
Uncertainty cap (+20% / -30% compared to Ay, only applied if b>1)1) | 0 |
Catch advice for 2024/2025 and 2025/20262) | 307 |
% advice change | 19 |
1) *[Ay × r × f × b × m] | |
2) 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 2024/2025 and 2025/2026 is higher than the advice for 2022/2023 because the biomass index has increased.
Prognosis
The recruitment has been low in the IS-SMH since 2010 and this is likely to lead to continued declines in biomass.
Quality of the assessment
The Icelandic autumn survey (IS-SMH) covers the full depth range and most of the geographical distribution of the stock and the fisheries within Icelandic waters. In most years since the beginning of the survey time series the catch has been mainly from Icelandic waters.
Advice, TAC and catch
Blue ling. Recommended TAC, national TAC, and catches (tonnes).
Fishing year | Recommended TAC | National TAC | Catches Iceland | Catches other | Total catch |
|---|---|---|---|---|---|
2010/2011 | 6 467 | 6 467 | |||
2011/2012 | 4 000 | 4 242 | 4 242 | ||
2012/2013 | 3 100 | 2 999 | 2 999 | ||
2013/2014 | 2 400 | 2 400 | 1 655 | 6 | 1 661 |
2015/2015 | 3 100 | 3 100 | |||
2015/2016 | 2 550 | 2 550 | 1 097 | 10 | 1 107 |
2016/2017 | 2 032 | 2 032 | 636 | 3 | 639 |
2017/2018 | 1 956 | 1 956 | 549 | 4 | 553 |
2018/2019 | 1 520 | 1 520 | 464 | 7 | 471 |
2019/2020 | 483 | 483 | 371 | 5 | 376 |
2020/2021 | 406 | 406 | 365 | 12 | 377 |
2021/2022 | 334 | 334 | 369 | 3 | 372 |
2022/2023 | 259 | 259 | 477 | 10 | 487 |
2023/2024 | 259 | 259 | |||
2024/2025 | 307 | ||||
2025/2026 | 307 |
References and further reading
ICES. 2021. Tenth Workshop on the Development of Quantitative Assessment Methodologies based on LIFE-history traits, exploitation characteristics, and other relevant parameters for data-limited stocks (WKLIFE X). ICES Scientific Reports. Report.
https://doi.org/10.17895/ices.pub.5985
MFRI Assessment Reports 2024. Blue ling. Marine and Freshwater Research Institute, 07 June 2024.
Stofnmatsskýrslur Hafrannsóknastofnunar 2024. Blálanga. Hafrannsóknastofnun 07. júní 2024.