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 risk A - 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. risk S - 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. risk S j - the probability that adult sardine biomass of stock j falls 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. risk S 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.

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.

Single Sardine Stock Management Procedure  S j=1,r βα ns risk A risk S CACA CSCS “New”No Catch 0.45N/A “Old” Interim OMP- 13 v2 (Single- area TAC) “New” Two-area TAC β west β south “New” “New” “New”

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

Two Sardine Stocks : No Catch NoMove: MoveB: 213 MoveE: 109

Two Sardine Stocks : No Catch Figure 2 NoMoveMoveB MoveE Assumption that k covE =1

Two Sardine Stocks : No Catch Figure 3 Average Biomass NoMoveMoveB MoveE

Two Sardine Stocks : No Catch Figure 4 NoMove MoveB MoveE Average Biomass

Two Sardine Stocks : No Catch Movement Model βα ns risk A risk S risk S west risk S south risk S west2 CACA CSCS C S west C S south NoMoveN/A Unfavorabl e Environ N/A MoveBN/A MoveEN/A Favorable Environ N/A

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

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

Two Sardine Stocks: Interim OMP-13 v2 Movement Model βα ns risk A risk S risk S west risk S south risk S west2 CACA CSCS C S west C S south NoMoveN/A MoveBN/A MoveEN/A NoMove MoveB MoveE No Catch Interim OMP-13 v2

Two Sardine Stocks : Two-area MP Movement Model βα ns risk A risk S risk S west risk S south risk S west2 CACA CSCS C S west C S south Single Area TAC (MoveE) NoMove MoveB MoveE NoMove MoveE MoveB MoveE No West Coast Same Betas

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

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