Advice and Scenarios Database



Witch (Glyptocephalus cynoglossus) in Subarea 4 and divisions 3.a and 7.d (North Sea, Skagerrak and Kattegat, eastern English Channel)
StockCode
wit.27.3a47d
Assessment Year
2021
Stock Category
1
Purpose
Advice
Published
Stock Assessment Key
16770
Link to Advice Sheet
https://doi.org/10.17895/ices.advice.7890






Catch scenarios


Basis
Total catch ^^
Projected landings
Projected discards *
Ftotal ages 4–8
Ftotal ages 4–8
SSB ^
SSB ^
% SSB change **
% advice change ***
2022 2022 2022 2022 2023 2022 2023 2023 2023
(t) (t) (t) (ratio) (ratio) (t) (t) (%) (%)
ICES Basis Advice
MSY approach: FMSY × SSB(2021)/MSY Btrigger 1206 1131 75 0.12 0.12 4141 5158 25 -30
Other scenarios
FMSY lower × SSB(2021)/MSY Btrigger 875 822 53 0.085 0.085 4213 5412 28 -50
F = 0 0 0 0 0 0 4397 6123 39 -100
Fpa 2608 2438 170 0.28 0.28 3811 4135 8.5 50
Flim 2925 2729 196 0.32 0.32 3727 3914 5 69
Fsq 2600 2431 169 0.28 0.28 3813 4140 8.6 50
SSB (2023) = Blim 4284 3976 308 0.51 0.51 3380 3078 -8.9 147
SSB (2023) = Bpa 2257 2113 144 0.24 0.24 3896 4381 12.4 30
SSB (2023) = MSY Btrigger 2257 2113 144 0.24 0.24 3896 4381 12.4 30
Rollover advice 1733 1627 106 0.177 0.177 4019 4838 20 0
FMSY 1462 1372 90 0.147 0.147 4083 4958 21 -15.6
FMSY lower 1067 1001 66 0.105 0.105 4174 5268 26 -38




Symbol Footnotes
* Including BMS landings, assuming recent discard rate (average of 2018–2020).
** SSB in 2023 relative to SSB in 2022.
*** Advice value for 2022 relative to advice value for 2021 (1733 tonnes).
^ SSB is estimated at spawning time (1 July).
^^ Other scenarios do not include FMSY upper because SSB(2021) is less than MSY Btrigger.