Advice and Scenarios Database



Megrim (Lepidorhombus spp.) in divisions 4.a and 6.a (northern North Sea, West of Scotland)
StockCode
lez.27.4a6a
Assessment Year
2018
Stock Category
1
Purpose
Advice
Published
Stock Assessment Key
9871
Link to Advice Sheet
https://doi.org/10.17895/ices.pub.4479






Catch scenarios


Basis
Total catch
Wanted catch*
Unwanted catch*
Fishing mortality F2019/FMSY
Stock size B2020/BMSY
Probability** of Biomass2020 falling below MSY Btrigger
Probability** of Biomass2020 falling below Blim
% B change ***
% TAC change ^
% Advice change^^
2019 2019 2019 2020 2020 2020 2020 2020 2019 2019
(t) (t) (t) (ratio) (ratio) (ratio) (ratio) (%) (%) (%)
ICES Basis Advice
MSY approach: FMSY 8250 7745 505 1 1.41 0.058 0 -15 3.7 5.8
Other scenarios
F= FMSYlower 6300 5914 386 0.77 1.51 0.04 0 -9 -20.8 -19.2
F= FMSYupper 8250 7745 505 1 1.42 0.062 0 -15 3.7 5.8
F= 0 0 0 0 0 1.82 0.01 0 9 -100 -100
B (2020)= Blim 32150 30182 1968 3.91 0.34 0.02 0.49 -79 304 312
B (2020)= MSYBpa 16450 15443 1007 2 1.02 0.5 0.01 -39 107 111
B (2020)= MSYBtrigger 16450 15443 1007 2 1.02 0.5 0.01 -39 107 111
F= F2018 2787 2616 171 0.33 1.66 0 0 0 -65 -64




Symbol Footnotes
* “Wanted” and “unwanted” catch are used to describe fish that would be landed and discarded, respectively, in the absence of the EU landing obligation (for Division 6.a only), based on discard rate estimates for 2014–2017.
** Probabilities are based on bootstrap sampling and based on a two- and three-year projection of F and B, respectively.
*** Biomass 2020 relative to biomass 2019.
^ Total catch in 2019 relative to TAC in 2018 (7958tonnes, which corresponds to the 2018 TAC for subareas 4 and 6).
^^ Advice value for 2019 relative to the advice value for 2018 (7800tonnes).