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The Cod Day

The Cod Day. Timetable. 11:00 ICES advice (July 2013) for North Sea and West of Scotland cod The third-quarter IBTS survey When to measure SSB for the North Sea cod management plan? (Coby Needle, MSS) 12:00 Exploring the catch forecast – options and implications (Carl O’Brien, CEFAS)

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The Cod Day

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  1. The Cod Day The Cod Day, Marine Laboratory, 1st October 2013

  2. Timetable • 11:00 • ICES advice (July 2013) for North Sea and West of Scotland cod • The third-quarter IBTS survey • When to measure SSB for the North Sea cod management plan? (Coby Needle, MSS) • 12:00 • Exploring the catch forecast – options and implications (Carl O’Brien, CEFAS) • 13:00 • Lunch • 13:30 • West coast discussion • 14:30 • Cod population structure (Peter Wright, MSS) • 14:45 • Sum up and close

  3. ICES advice for North Sea and West of Scotland cod: July 2013 Dr Coby Needle Marine Laboratory, Aberdeen The Cod Day, Marine Laboratory, 1st October 2013

  4. North Sea cod • Assumed to be no unaccounted removals since 2006 • F low and falling, SSB low and rising, long run of low recruitment

  5. North Sea cod • Discarding remains high, although rates for older fish are lower than in recent years.

  6. North Sea cod • Now in the “long-term” phase of the management plan: • Assume F(2013) = F(2012): “no reduction in effort ceilings” • Target F(2014) determined by rule = 0.21 • TAC constraint ±20% Target F F(2014) = 0.21 B(2013) = 72 kt B(lim) B(pa) SSB

  7. North Sea cod

  8. North Sea cod • Summary text: • “ICES advises on the basis of the EU–Norway management plan that landings in 2014 should be no more than 28 809 tonnes. If discards rates do not change from those in 2012, this implies catches of no more than 37 496 tonnes.” • F low and falling, SSB low and rising • BUT long run of low recruitment • AND adult stock currently concentrated in the main fishing areas for Scotland

  9. West of Scotland cod • F remains high • SSB remains low • Long run of low recruitment

  10. West of Scotland cod • Discarding remains high • Discard mortality higher than landings mortality

  11. West of Scotland cod

  12. West of Scotland cod • Summary text: • “ICES advises on the basis of the MSY approach that there should be no directed fisheries and that bycatch and discards should be minimized.” • Management measures have not constrained catches • F remains high • SSB very low • Impaired recruitment

  13. The 3rd-quarter IBTS survey: its effect and why it isn’t currently used Dr Coby Needle Marine Laboratory, Aberdeen The Cod Day, Marine Laboratory, 1st October 2013

  14. IBTS surveys • Multinational surveys coordinated by ICES • Two surveys: 1st and 3rd quarters • Since 2011, the North Sea cod assessment has only used IBTS Q1. • Two main questions: • What effect did IBTS Q3 have on the assessment in 2011? • Why is it no longer used?

  15. WKCOD 2011

  16. The effect of IBTS Q3 • Two assessments carried out using catch data and either one of the IBTS surveys • IBTS Q1 indicated declining or stable mortality rates (F) • IBTS Q3 indicated increasing mortality rates (F) Source: ICES WGNSSK (2010)

  17. The effect of IBTS Q3 • Two assessments carried out using catch data and either one of the IBTS surveys • IBTS Q1 indicated declining or stable mortality rates (F) • IBTS Q3 indicated increasing mortality rates (F) • Significant difference • Indication from IBTS Q3 contradicted widespread perceptions of a reduction in fishing activity on cod. • Further analysis was called for…

  18. IBTS Q3 catchability • Several papers at WKCOD analysed IBTS Q3 catchability. • Findings: • Analysis of how survey indices change between quarters and through years suggests that the catchability of IBTS Q3 has increased in recent years • That is: IBTS Q3 “sees” comparatively more cod in recent years than IBTS Q1, or than IBTS Q3 in earlier years (up to 60% more) • But this leads to an indication of higher fishing mortality • No valid explanation for the effect

  19. Conclusions • WKCOD concluded that IBTS Q1 is more likely to reflect true stock size: • No observed change in catchability for IBTS Q1 so deemed more reliable • Observed changes in catchability for IBTS Q3 so deemed less reliable • Hence assessment now based on IBTS Q1 and catch data only. • Unlikely to be changed before next benchmark • Scheduled 2015

  20. When to measure SSB in the cod management plan? Dr Coby Needle Marine Laboratory, Aberdeen The Cod Day, Marine Laboratory, 1st October 2013

  21. Measuring SSB • The current cod management plan bases decisions on: • “the size of the stock on 1 January of the year prior to the year of application of the TACs” • e.g. For advice produced in July 2013, this would be 1 January 2013 • Less uncertainty • But no account of the fishery in 2013, or the forecasted fishery in 2014

  22. Measuring SSB • Other management plans (e.g. for several haddock stocks) use: • “the SSB in the end of the year in which the TAC is applied” • e.g. For advice produced in 2013, this would be 1 January 2015 • More uncertainty • But does account for fishery during 2013 and 2014 • Difference can be significant • Cod MP was evaluated assuming SSB at start of year prior to quota year • Can’t be changed without re-evaluation of MP

  23. Cod populations around the UK Dr Peter Wright Marine Laboratory, Aberdeen The Cod Day, Marine Laboratory, 1st October 2013

  24. Genetic and tagging evidence for populations 3 genetically differentiated populations around the UK Adult cod do not range across stock regions

  25. Genetic and tagging evidence for populations Viking centred group never leaves cool, deep waters Adults mostly found close to release sites near spawning Some exchange during feeding

  26. Larval - adult movements of 2007 year-class

  27. Sub-population dynamics: local SSB Sub-areas Index based on 1st quarter IBTS & SGFS WESTCOAST p <0.001 p <0.01 NORTH SEA > decline of coastal units NW S NE p <0.001 Holmes, Wright & Fryer, 2008 ICES JMS, 65: 206-215

  28. Cod mature and grow at different rates Higher and more variable growth in the south Slower growth and larger size at maturity in NE Wright, Millar & Gibb (2011), ICESJMS, 68, 1918-27

  29. Uncertainty over extent of NE cod cod have same Lp50 as NE cod cod have same Lp50 as NW cod New FISA starting soon to estimate boundaries

  30. North / south split in stock trends from surveys • From IBTS survey index: • Difference in the north: • 277% for age 2 • 257% for age 3+ • Difference in the south: • 93% for age 2 • 152% for age 3+ • Vessels fishing in the north are likely to have seen a much greater increase in the cod stock than vessels fishing in the south 2006 2013 Age 2 Age 3+

  31. West coast management discussions The Cod Day, Marine Laboratory, 1st October 2013

  32. West coast cod

  33. West coast cod

  34. West coast cod

  35. TR2 catch

  36. TR1 discards

  37. TR1 catch rate (observer)

  38. West coast

  39. West coast

  40. West coast

  41. West coast

  42. West coast

  43. West coast

  44. West coast

  45. West coast

  46. West coast

  47. West coast

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