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The Cod DayMarine Laboratory, Aberdeen, 2 October 2012
The Cod Day - Science
Coby Needle, Nick Bailey, Rui Catarino, Steven Holmes
Marine Laboratory
Aberdeen
Outline
• North Sea cod• West of Scotland cod• Future developments
North Sea cod – Outline
• Data– Stock area– Catch data– Survey data– Stock distribution– Value estimates– Sampling and observer coverage– Biological data
• Assessment• Advice
North Sea cod – stock area
North Sea cod – official landings
Belgium2%
Denmark18%
France2%
Germany8%
Netherlands7%
Norway18%
Sweden1%
Scotland36%
England & Wales8%
North Sea cod – Int. effort
TR1 = Trawl gear with mesh ≥ 100mm
North Sea cod – Int. effort
TR2 = Trawl gear with mesh ≥ 70mm & < 100mm
North Sea cod – Int. effort
GN = Gill nets & entangling nets
Reg. gear 2011
TR1 68.8%
TR2 11.6%
GN 10.8%
BT2 5.2%
BT1 1.6%
GT 1.3%
LL 0.7%
TR3 V small %
North Sea cod – Int. cod catch
North Sea cod – catches
2011 Removals = 67 ktLandings = 35 kt (52%), discards = 11.7 kt (17%), unaccounted = 20.3 kt
Unaccounted
Discards
Landings
North Sea cod – surveys
• Available surveys:– IBTS Q1 1983-2012– IBTS Q3 1991-2011– ScoGFS Q3 1982-2011– EngGFS Q3 1992-2011– North Sea Commission Fishers’ Survey
• Only IBTS Q1 used in assessment– Possible changes in catchability in Q3– Fishers’ Survey not quantitative
North Sea cod – surveys
IBTS Q1
2008 age 1 2009 age 1 2010 age 1 2011 age 1 2012 age 1
2008 age 2 2009 age 2 2010 age 2 2011 age 2 2012 age 2
2008 age 3+ 2009 age 3+ 2010 age 3+ 2011 age 3+ 2012 age 3+
North Sea cod – surveys
IBTS Q1
North Sea cod – surveys
North SeaCommission
Fishers’Survey 2011
North Sea cod – modelled abundance distribution
North Sea cod – modelled abundance distribution
North Sea cod – modelled abundance distribution
North Sea cod – modelled abundance distribution
North Sea cod – modelled abundance distribution
North Sea cod – modelled abundance distribution
North Sea cod – VMS-based landings distribution
4°E0°4°W8°W12°W
62°N
58°N
54°N
50°N
Cod LPUE 2007
Legend
kg year
0 - 5,000
5,001 - 15,000
15,001 - 30,000
30,001 - 45,000
45,001 - 75,000
75,001 - 125,000
125,001 - 270,000
North Sea cod – VMS-based landings distribution
4°E0°4°W8°W12°W
62°N
58°N
54°N
50°N
Cod LPUE 2008
Legend
kg year
0 - 5,000
5,001 - 15,000
15,001 - 30,000
30,001 - 45,000
45,001 - 75,000
75,001 - 125,000
125,001 - 270,000
North Sea cod – VMS-based landings distribution
4°E0°4°W8°W12°W
62°N
58°N
54°N
50°N
Cod LPUE 2009
Legend
kg year
0 - 5,000
5,001 - 15,000
15,001 - 30,000
30,001 - 45,000
45,001 - 75,000
75,001 - 125,000
125,001 - 270,000
North Sea cod – VMS-based landings distribution
4°E0°4°W8°W12°W
62°N
58°N
54°N
50°N
Cod LPUE 2010
Legend
kg year
0 - 5,000
5,001 - 15,000
15,001 - 30,000
30,001 - 45,000
45,001 - 75,000
75,001 - 125,000
125,001 - 270,000
North Sea cod – VMS-based landings distribution
4°E0°4°W8°W12°W
62°N
58°N
54°N
50°N
Cod LPUE 2011
Legend
kg year
0 - 5,000
5,001 - 15,000
15,001 - 30,000
30,001 - 45,000
45,001 - 75,000
75,001 - 125,000
125,001 - 270,000
North Sea cod – observer coverage 2011
Fleet Declared landings (tonnes)
Number of trips sampled
Discard weight (tonnes)
Discard rate
All 10505 39 3414 24.5%
TR1 (whitefish)
10228 28 2529 19.8%
TR2 (Nephrops)
222 11 885 79.9%
North Sea cod – observer coverage 2011
North Sea cod – observer coverage 2011
North Sea cod – observer coverage 2011
North Sea cod – port sampling coverage 2011
Fleet Declared landings (tonnes)
Number of trips
Number of trips sampled
Number of fish measured
Number of otoliths taken
All 10773 5180 39 10205 4546
North Sea cod – mean weight-at-age in catches
0
2
4
6
8
10
12
14
16
1960 1970 1980 1990 2000 2010
kg
Mean weights-at-age in stock/catch
Age 1
Age 2
Age 3
Age 4
Age 5
Age 6
Age 7
Age 8
Age 9
North Sea cod – natural mortality estimates
0.000
0.200
0.400
0.600
0.800
1.000
1.200
1.400
1958 1968 1978 1988 1998 2008 2018
Age 1
Age 2
Age 3
Age 4
Age 5
North Sea cod – maturity estimates
0
0.2
0.4
0.6
0.8
1
1.2
0 1 2 3 4 5 6 7
Age
Pro
port
ion
mat
ure
North Sea cod – assessment
• Assessed using the SAM method– Includes IBTS Q1 survey, landings, discards– Landings and discards from 1993-2011 are
scaled by an estimated parameter– Indicates unaccounted removals
• SAM is a robust approach and is increasingly widely used at ICES– SAM: NS cod, western Baltic plaice, NS sole,
Kattegat cod, NS herring– TSA: Cod VIa, haddock VIa
North Sea cod – assessment
North Sea cod – assessment
Fmp
North Sea cod – assessment
North Sea cod – assessment
Removals
North Sea cod – assessment
Removals multiplier
North Sea cod – forecasts & advice (June 2012)
• Reduce F in steps from 2008 onwards:– 2009 F = 75% 2008 F– 2010 F = 65% 2008 F– 2011 F = 55% 2008 F– And so on…
• Most recent estimate of 2008 F used at each step.
• Apply sliding-F rule:
Management plan has two phases:
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0 50 100 150 200
SSB at start of current year (000 tonnes)
Targ
et F
Blim Bpa
#1 used until suggested TAC is lower than that from #2,or F = 0.4 for three years
North Sea cod – forecasts & advice (June 2012)
• For both management plan phases:– Maximum effort reduced in line with F (but with bycatch rules).– ± 20% constraint on annual quota changes.– Forecasts based on estimate total removals, which are then split
into:• Landings (quota).• Discards.• Unaccounted removals.
• Other Articles relevant also, e.g.:– Article 9: data-poor situations.– Article 10: different approach if recovery not working.– Article 13: derogations to reduce effort cuts.
North Sea cod – forecasts & advice (June 2012)
• MSY:– F(msy)
• MSY framework:– F’ = F(msy) * SSB(2012) / B(pa)
• MSY transition rule:– More gradual shift to F(msy)
• Zero catch• Roll-over landings• [Mixed-fisheries advice]
North Sea cod – forecasts & advice (June 2012)
• Two versions of advice depending on intermediate year (2012) assumptions:– Table A: management plan followed in 2012,
giving 18% reduction in F.– Table B: recent trend in F continues, giving
12% reduction in F.
• ICES recommends Table B.
North Sea cod – forecasts & advice (June 2012)
Rationale Basis Ftotal 2013
Landings 2013
Discards 2013
Unalloc 2013
SSB 2014
dSSB dTAC
Management plan
TAC cons.
0.26 25.4 6.5 8.6 107 +37%
-20%
Table A: (note 2012 TAC = 31.8)
North Sea cod – forecasts & advice (June 2012)
Rationale Basis Ftotal 2013
Landings 2013
Discards 2013
Unalloc 2013
SSB 2014
dSSB dTAC
Management plan
TAC cons.
0.27 25.4 6.6 8.6 103 +36%
-20%
MSY F msy
0.19 19 4.9 6.4 112 +47%
-41%
MSY framework
F’ 0.10 10 2.5 3.4 123 +63%
-69%
MSY transition
Rule 0.29 28 7.2 9.4 101 +33%
-13%
Zero catch F = 0 0.00 0 0.0 0.0 136 +80%
-100%
Rollover landings
Landings 2012
0.49 43 11.5 14.6 82 +8% +34%
Table B: (note 2012 TAC = 31.8)
West of Scotland cod
• See next file…
North Sea cod – TR1 value maps
North Sea cod – TR1 value maps
North Sea cod – TR1 value maps
North Sea cod – TR1 value maps
North Sea cod – TR2 value maps
North Sea cod – TR2 value maps
North Sea cod – TR2 value maps
North Sea cod – TR2 value maps
Future developments – CCTV estimates of discard rates
• Work progressing on discard-rate estimation
• Potentially a very important data source• Several current limitations:
– Resources (equipment and staff)– Methodology– Quality of data
Future developments – CCTV estimates of discard rates
Future developments – CCTV estimates of discard rates
• Work progressing on discard-rate estimation
• Potentially a very important data source• Several current limitations:
– Resources (equipment and staff)– Methodology– Quality of data
• Hope to maintain cameras at least for scientific observation
Future developments – draft management area proposals
North Sea, Skaggerak,Eastern ChannelRockall
IrishSea
Baltic
West ofScotland
North Sea, Skaggerak,Eastern ChannelRockall
IrishSea
Baltic
West ofScotland
Future developments – draft management area proposals
Northern NS and Shelf
Southern NS
Rockall
Wider Celtic Seas
IrishSea
Baltic