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Initial Results Using a Two-Area Directed Sardine TAC

Initial Results Using a Two-Area Directed Sardine TAC. SPSWG Meeting 31 st October 2013 Carryn de Moor Doug Butterworth William Robinson. Marine Resource Assessment and Management Group (MARAM) Department of Mathematics and Applied Mathematics University of Cape Town. Risk Definitions.

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Initial Results Using a Two-Area Directed Sardine TAC

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  1. Initial Results Using a Two-Area Directed Sardine TAC SPSWG Meeting 31st October 2013 Carryn de Moor Doug Butterworth William Robinson Marine Resource Assessment and Management Group (MARAM) Department of Mathematics and Applied Mathematics University of Cape Town

  2. Risk Definitions • riskA - the probability that total adult anchovy biomass falls below 10% of the average total adult anchovy biomass over November 1984 and November 1999 at least once during the projection period of 20 years. • riskS - the probability that total adult sardine biomass falls below the average total adult sardine biomass over November 1991 and November 1994 at least once during the projection period of 20 years. • riskS j - the probability that adult sardine biomass of stock jfalls below the average adult sardine biomass of stock j over November 1991 and November 1994 at least once during the projection period of 20 years. • riskS west2 - the probability that adult “west” stock sardine biomass falls below the average adult “west” stock sardine biomass over November 2004 and November 2011 at least once during the projection period of 20 years.

  3. Movement Hypotheses • NoMove – no future movement • MoveB– future movement is based on a relationship with the ratio of “south” : “west” stock 1+ biomass • MoveE – future movement “switches” between increasing and decreasing towards an equilibrium proportion, based on whether a favorable or unfavorable environment exists on the south coast.

  4. Single Sardine Stock

  5. Two Sardine Stocks : No Catch Biomass above which maximum recruitment would occur on average Figure 1

  6. Two Sardine Stocks : No Catch NoMove: 1946 MoveB: 213 MoveE: 109 105

  7. Two Sardine Stocks : No Catch NoMove MoveB MoveE Assumption that kcovE=1 Figure 2

  8. Two Sardine Stocks : No Catch NoMove MoveB MoveE Average 91-94 1+ Biomass Figure 3

  9. Two Sardine Stocks : No Catch MoveB NoMove MoveE Average 91-94 1+ Biomass Figure 4

  10. Two Sardine Stocks : No Catch

  11. Two Sardine Stocks : Catch Scenarios NoMove MoveB Single Area (Interim OMP-13v2) Two Area (same betas) Two Area (no west coast TAC) Comparing Median West SSB Between Alternative Catch Scenarios MoveE Figures 5,10,15

  12. Two Sardine Stocks : Catch Scenarios NoMove MoveB Single Area (Interim OMP-13v2) Two Area (same betas) Two Area (no west coast TAC) Comparing Median South SSB Between Alternative Catch Scenarios MoveE Figures 6,11,16

  13. Two Sardine Stocks: Interim OMP-13 v2 No Catch Interim OMP-13 v2

  14. Two Sardine Stocks : Two-area MP Same Betas No West Coast

  15. Two Sardine Stocks : Catch Scenarios NoMove MoveB Single Area (Interim OMP-13v2) Two Area (same betas) Two Area (no west coast TAC) Comparing Median Total Catch Between Alternative Catch Scenarios MoveE Figures 7,12,17

  16. Initial Results Using a Two-Area Directed Sardine TAC Thank you for your attention

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