Advice and Scenarios Database



Whiting (Merlangius merlangus) in Subarea 4 and Division 7.d (North Sea and eastern English Channel)
StockCode
whg.27.47d
Assessment Year
2019
Stock Category
1
Purpose
Advice
Published
Stock Assessment Key
11587
Link to Advice Sheet
https://doi.org/10.17895/ices.advice.4878






Catch scenarios


Basis
Total catch
Total wanted catch*
Total unwanted catch*
Total IBC**
HCF catch 4+7.d
HCF catch 4***
HCF catch 7.d***
Total F (ages 2–6)+
F (wanted catch, ages 2–6)
F (unwanted catch, ages 2–6)
F (IBC, ages 2–6)++
SSB
% SSB change ^
% TAC change (HCF catch 4)^^
% Advice change^^^
2020 2020 2020 2020 2020 2020 2020 2020 2020 2020 2020 2021 2021 2021 2021
(t) (t) (t) (t) (t) (t) (t) (ratio) (ratio) (ratio) (ratio) (t) (%) (%) (%)
ICES Basis Advice
MSY approach: FMSY × SSB (2020)/MSY Btrigger 22082 12737 6617 2728 19354 15036 4318 0.162 0.098 0.044 0.02 156981 0.25 -12.5 -8.7
Other scenarios
F = FMSY = FMSY upper## 23413 13611 7086 2716 20697 16079 4617 0.172 0.105 0.047 0.02 156045 -0.35 -6.5 -3.2
F = FMSY lower 21628 12438 6458 2732 18896 14680 4216 0.158 0.095 0.043 0.02 157301 0.45 -14.6 -10.6
F = MAP FMSY lower ×SSB(2020)/MSYBtrigger# 20406 11635 6028 2743 17663 13722 3941 0.148 0.088 0.04 0.02 158160 1 -20 -15.7
F2020 = 0 (IBC only) 2899 0 0 2899 0 0 0 0.02 0 0 0.02 170621 9 -100 -88
F2020 = F2019 26855 15873 8297 2685 24169 18777 5392 0.199 0.123 0.056 0.02 153624 -1.89 9.2 11
Roll-over TAC 24831 14543 7585 2703 22131 17191 4937 0.183 0.112 0.051 0.02 155048 -0.98 0 2.6
15% TAC decrease (27.4 only) 21542 12380 6428 2733 18817 14612 4196 0.157 0.095 0.043 0.02 157363 0.49 -15 -11
15% TAC increase (27.4 only) 28121 16705 8742 2674 25445 19770 5677 0.21 0.13 0.059 0.02 152733 -2.5 15 16.2
0.75 × F2019+++ 21130 12111 6282 2737 18393 14290 4103 0.154 0.092 0.042 0.02 157651 0.68 -16.9 -12.7
1.25 × F2019+++ 32535 19605 10295 2634 29900 23230 6671 0.24 0.154 0.07 0.02 149628 -4.4 35 34
Fpa 43554 26846 14172 2535 41018 31867 9151 0.33 0.21 0.097 0.02 141876 -9.4 85 80
Flim 59870 37568 19914 2389 57482 44657 12824 0.46 0.3 0.136 0.02 130397 -16.7 160 147
SSB (2021) = Bpa= MSYBtrigger 8298 3679 1767 2852 5446 4231 1215 0.053 0.023 0.01 0.02 166708 6.4 -75 -66
SSB (2021) = Blim 74583 47236 25091 2256 72327 56190 16136 0.57 0.38 0.172 0.02 119970 -23 227 208




Symbol Footnotes
* “Wanted” and “unwanted” catch are used to described fish that would be landed and discarded in the absence of the EU landing obligation, based on discard rate estimates for 2016–2018.
** The split of catch between wanted catch, unwanted catch, and industrial bycatch (IBC) in 2020 was done using partial age-dependent fishing mortalities as forecasting input. Partial Fs were calculated based on total F-at-age and the numbers-at-age per catch category as estimated in the assessment (average exploitation pattern of the three most recent years).
*** The human consumption fishery (HCF) catch split between Subarea 4 and Division 7.d in 2019 and 2020 is the same as the proportion of HCF catch between the areas in 2018: 77.7% from Subarea 4 and 22.3% from Division 7.d. This assumes that management for Division 7.d is separate from Subarea 7. Total catches are based on a combined discard rate for Subarea 4 and Division 7.d.
# EU multiannual plan (MAP) for the North Sea (EU, 2018).
## For this stock, FMSY upper = FMSY.
^ SSB 2021 relative to SSB 2020.
^^ Human consumption fishery catch (HCF catch) for Subarea 4 in 2020 relative to TAC for Subarea 4 and Division 2.a in 2019 (17 191 tonnes).
^^^ Total catch 2020 relative to the advice value 2019 (24 195 tonnes).
+ Total F is calculated as the sum of partial fishing mortalities.
++ F(IBC) is assumed to be constant in all scenarios at status quo value.
+++ Multiplier only applied to F(UW) and F(WC), with F(IBC) constant.