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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

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The cod day science

The Cod Day - Science

Coby Needle, Nick Bailey,

Rui Catarino, Steven Holmes

Marine Laboratory

Aberdeen

The Cod Day

Marine Laboratory, Aberdeen, 2 October 2012


Outline
Outline

  • North Sea cod

  • West of Scotland cod

  • Future developments


North sea cod outline
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 int effort
North Sea cod – Int. effort

TR1 = Trawl gear with mesh ≥ 100mm


North sea cod int effort1
North Sea cod – Int. effort

TR2 = Trawl gear with mesh ≥ 70mm

& < 100mm


North sea cod int effort2
North Sea cod – Int. effort

GN = Gill nets & entangling nets



North sea cod catches
North Sea cod – catches

Unaccounted

Discards

Landings

2011 Removals = 67 kt

Landings = 35 kt (52%), discards = 11.7 kt (17%), unaccounted = 20.3 kt


North sea cod surveys
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 surveys1
North Sea cod – surveys

2009 age 1

2012 age 1

2010 age 1

2011 age 1

2008 age 1

IBTS

Q1

2009 age 2

2012 age 2

2010 age 2

2011 age 2

2008 age 2

2009 age 3+

2012 age 3+

2010 age 3+

2011 age 3+

2008 age 3+



North sea cod surveys3
North Sea cod – surveys

North Sea

Commission

Fishers’

Survey 2011


















North sea cod mean weight at age in catches
North Sea cod – mean weight-at-age in catches

Age 9

Age 8

Age 7

Age 6

Age 5

Age 4

Age 3

Age 2

Age 1




North sea cod assessment
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 assessment5
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:

North Sea cod – forecasts & advice (June 2012)

Management plan has two phases:

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 20121
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 20122
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 20123
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 20124
North Sea cod – forecasts & advice (June 2012)

Table A: (note 2012 TAC = 31.8)


North sea cod forecasts advice june 20125
North Sea cod – forecasts & advice (June 2012)

Table B: (note 2012 TAC = 31.8)


West of scotland cod
West of Scotland cod

  • See next file…






North sea cod tr2 value maps
North Sea cod – TR2 value maps

DRAFT - some edits required


North sea cod tr2 value maps1
North Sea cod – TR2 value maps

DRAFT - some edits required


North sea cod tr2 value maps2
North Sea cod – TR2 value maps

DRAFT - some edits required


North sea cod tr2 value maps3
North Sea cod – TR2 value maps

DRAFT - some edits required


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



Future developments cctv estimates of discard rates2
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




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