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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.
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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