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

WoS cod – stock area

WoS cod – official landings

UK50%

France27%

Ireland19%

Norway4%

Others0%

WoS cod – catches

2011 Removals = 6.36 ktLandings = 0.52 kt (8%), discards = 5.84 kt (92%)

WoS cod – surveys

• Available surveys:– ScoGFS-WIBTS-Q1: 1985–2010

• Became UKSGFS-WIBTS-Q1 in 2011– ScoGFS-WIBTS-Q4: 1996-2009

• Became UKSGFS-WIBTS-Q4 in 2011– IGFS-WIBTS-Q4

• Only ScoGFS-WIBTS-Q1 used in assessment

• 2013 assessment: Too soon to use UKSGFS (& stock subject to 1.5% bycatch rule).

WoS cod – surveys

WoS cod – surveys

WoS cod – surveysQ4 2010 Q4 2011

WoS cod – Int. effort

TR1 = Trawl gear with mesh ≥ 100mm

WoS cod – Int. effort

TR2 = Trawl gear with mesh ≥ 70mm & < 100mm

WoS cod – Int. effort

LL = Long Lines

WoS cod – Int. effort

GN = Gill nets & entangling nets

Reg. gear 2011 % Av. 09-11 %

TR1 92.8% 95%TR2 6.98% 5%GN1 0.22% V small %Others V small % V small %

WoS cod – Int. cod catch

WoS – TR1 landings

COD

ANGLER

HADDOCK

SAITHE

WoS – TR1 & TR2 landings

WHITING

NEPHROPS

WoS cod – observer coverage 2011

Fleet Declared landings (tonnes)

Number of trips sampled

Discard weight (tonnes)

Discard rate

All 110 15 1572 93.5%

TR1 (whitefish)

102 8 1439 93.4%

TR2 (Nephrops)

8 7 133 94.3%

WoS cod – port sampling coverage 2011

Demersal trips landing cod

614

Demersal trips landing cod – that were sampled

12

% of trips sampled 2%No. fish measured 158No. otoliths taken (for ageing)

123

CV on total numbers 0.14

WoS cod – mean weight-at-age in catches

WoS cod – natural mortality estimates

1980 1985 1990 1995 2000 2005 2010

0.0

0.1

0.2

0.3

0.4

0.5

0.6

Year

M

Age 1Age 2Age 3Age 4Age 5Age 6Age 7

WoS cod – assessment

• Assessed using the TSA method– Includes ScoGFS-WIBTS-Q1 survey, landings &

discards– Landings 1995-2005 not used (suspected as

biased)– No survey data for 2011-2012.

• TSA - same basic approach as SAM model but developed in house (Rob Fryer)

WoS cod – assessment

WoS cod – assessment

WoS cod – assessment

0

5

10

15

20

25

30

35

40

45

0,0 0,5 1,0 1,5

SSB

in 1

000

t

Fishing Mortality (ages 2-5)

2011

WoS cod mortality – lnds vs dis

WoS cod – assessment

0

5

10

15

20

25

catch

0

1

2

3

4

5

6discards

0

5

10

15

20

25

landings

0.0

0.5

1.0

19801990 2000 2010

mean F (ages 2-5)

0

20

40

60

1980199020002010

recruitment

0

10

20

30

40

1980199020002010

SSB

0

5

10

15

20

25

catch

0

1

2

3

4

5

6discards

0

5

10

15

20

25

landings

0.0

0.5

1.0

1980199020002010

mean F (ages 2-5)

0

20

40

60

198019902000 2010

recruitment

0

10

20

30

40

1980199020002010

SSB

WoS cod – area misreporting

2002 2004 2006 2008 2010

-100

010

020

030

040

050

0

Year

Add

ition

to o

ffici

al V

Ia la

ndin

gs (t

onne

s)

under-reportingmis-reportingnet difference

WoS cod – Management plan

• Unlike N Sea F reduction only related to previous year

• Reduction depends on prediction of SSB at start of TAC year:– 25% reduction in F if SSB < Blim– 15% reduction in F if Blim < SSB < Bpa– Min(10% reduction in F or F=0.4) if SSB > Bpa

• But 20% limit to changes in TAC• But But 25% TAC reduction if stock

unhealthy yet ‘data poor’ • Also – ICES has never accepted

management plan as precautionary

WoS cod – Advice

• MSY approach– MSY framework: TAC = 30 t– MSY transition: TAC = 270 t

• But because SSB << Blim advice was for zero catch