LÝSA Merlangius merlangus
Publication of Advice: 7 June 2024. Published by Marine and Freshwater Research Institute.
Advice
MFRI advises in accordance with the MSY approach that catches in the fishing year 2024/2025 should be no more than 1 571 tonnes.
Stock development
Stock size is above Itrigger and the fishing pressure is below FMSY proxy.
Whiting. Catches by gear type, IS-SMB juvenile index (≤20 cm), fishing pressure proxy (FMSYproxy) and IS-SMB biomass (≥40 cm) index. Shaded area and bars 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 | Trends in biomass indicators |
Input data | Commercial catch and survey biomass indices (IS-SMB) |
Approach | Reference point | Value | Basis |
|---|---|---|---|
MSY approach | Itrigger | 2.15194 | Iloss defined as the mean IS-SMB survey index 1985–1999 |
FMSY proxy | 0.16 | Average of the ratio of catch to biomass index for the years for which the fishing pressure proxy relative to MSY proxy (f) > 1, where f = Lmean/LF=γM,K=ϴM is based on Lc (length at 50% of modal abundance), which varies each year. |
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. (Category 3 stocks; ICES,2021). The IS-SMB survey index for whiting ≥40 cm is multiplied by an FMSY,proxy, a biomass safeguard (b), and a precautionary multiplier (m). The stability clause was applied since the increase from the previous advice is greater than 20%.
Whiting. Advice calculation.
Ay: Catch advice for 2023/2024 | 1 309 |
Biomass index | |
Latest index value (I2024) | 25 762 |
Fishing pressure proxy** | |
FMSY proxy: MSY proxy harvest rate (average of the ratio of catch to biomass index for the years for which f>1, where f = Lmean/ LF = γM,K = ϴM ) | 0.161 |
Biomass safeguard | |
Index trigger value (Itrigger=Iloss*1.4) | 2 152 |
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) | 0.5 |
Advice calculation1) | 2 080 |
Uncertainty cap (+20% / -30% compared to Ay, only applied if b>1) | 1 |
Catch advice for 2024/2025 | 1 571 |
% advice change2) | 20 |
1) A~y+1~ = I~y~ × F~MSY proxy~ × b × m, limited by stability clause | |
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 this fishing year is higher than the advice for last year because the biomass index has increased.
Prospects
Recruitment was low in 2009–2014 but has increased since then.
Quality of Assessment
IS-SMB covers the geographical distribution of the fisheries.
Advice, TAC and Catch
Whiting. Recommended TAC, national TAC, and catches (tonnes).
Fishing year | Recommended TAC | National TAC | Total catch |
|---|---|---|---|
2019/2020 | 836 | 607 | |
2020/2021 | 1 003 | 844 | |
2021/2022 | 1 137 | 826 | |
2022/2023 | 1 091 | 1 252 | |
2023/2024 | 1 309 | ||
2024/2025 | 1 571 |
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
Stofnmatsskýrslur Hafrannsóknastofnunar 2024. Lýsa. Hafrannsóknastofnun, 7. júní 2024.