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Draft Two-Area Harvest Control Rules for OMP-13 SPSWG Meeting 31 st October 2013 Carryn de Moor Doug Butterworth Marine Resource Assessment and Management.

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Presentation on theme: "Draft Two-Area Harvest Control Rules for OMP-13 SPSWG Meeting 31 st October 2013 Carryn de Moor Doug Butterworth Marine Resource Assessment and Management."— Presentation transcript:

1 Draft Two-Area Harvest Control Rules for OMP-13 SPSWG Meeting 31 st October 2013 Carryn de Moor Doug Butterworth Marine Resource Assessment and Management Group (MARAM) Department of Mathematics and Applied Mathematics University of Cape Town

2 Two-Area HCRs The type of sardine TAC arising from the candidate MP Single area TACTwo area TAC The underlying sardine stock operating model Single sardine stock Two mixing sardine stocks Used to develop Interim OMP-13 v2 eg given in SWG-PEL Doc #27 Now developed

3 Two-Area HCRs Interim OMP-13 v2 – single area directed sardine TAC Alternative MP – directed sardine TACs for west/south of Cape Agulhas Draft – maintained same/similar constraints as Interim OMP-13 v2

4 Some Assumptions Sardine TAB with anchovy – initial ratio is based on observed sardine 1+ biomass. For comparability, the total sardine 1+ biomass is used When simulation testing a 2-area HCR assuming a single sardine stock, future observations west/south of Cape Agulhas are drawn from proportions observed from or 00-11

5 Some Assumptions If Sardine ECs are declared, the ‘top up’ after the recruit survey is dependent on observed recruitment up to Cape Infanta only

6 HCR Control Parameters & Constraints ParameterFixed TABsInterim OMP-13 v2 TAB S big Fixed >14cm sardine bycatch7 000t TAB A Fixed anchovy bycatch for sardine only right holders 500t TAB S y,smallrh Fixed ≤14cm sardine bycatch with round herring1 000t No Change Small (<14cm) sardine bycatch with directed  14cm sardine: Set as a proportion of directed sardine TAC and thus also split proportionally by area

7 HCR Control Parameters & Constraints No Change: -Anchovy HCR parameters (eg scale down factor, , weighting given to recruitment survey in anchovy TAC, p, etc.) -Anchovy historic averages used in TAC formulae -Anchovy constraints (max, min, max dec, 2- tier etc.) -Sardine TAB with anchovy control parameters

8 HCR Control Parameters & Constraints ParameterFixed TABsInterim OMP-13 v2 c S mntac Minimum ≥14cm directed sardine TAC 90 c S mxtac Maximum ≥14cm directed sardine TAC 500 Applies to combined TAC. Proportion of Min/Max allocated west/south of Cape Agulhas is the same as that prior to the constraint being enforced c S tier Two-tier threshold for ≥14cm directed sardine TAC 255 c S mxdn Maximum proportion by which ≥14cm directed sardine TAC can be reduced annually 0.20 The decision on which constraint on the maximum inter-annual decrease in TAC is applied, depends on the combined TAC If below the 2-tier threshold, the TAC west/south of Cape Agulhas is restricted to at most a 20% decrease from the TAC in that area in the previous year If above the 2-tier threshold, the combined TAC is 0.8c S tier, with the proportion of TAC allocated west/south of Cape Agulhas being the same as that prior to the constraint being enforced

9 HCR Control Parameters & Constraints ParameterFixed TABsInterim OMP-13 v2 B S ec Threshold at which Exceptional Circumstances are invoked for sardine 300 SS Threshold above B s ec at which linear smoothing is introduced before sardine Exceptional Circumstances are declared (to ensure continuity) 400 xSxS Proportion of B S ec below which sardine TAC is zero 0.25 The combined observed biomass west/south of Cape Agulhas is used to determine whether Exceptional Circumstances or Linear Smoothing applies The total TAC under Exceptional Circumstances is calculated based on the combined biomass. The proportion of this biomass allocated west/south of Cape Agulhas is the same as that prior to the constraint being enforced (There is likely some discontinuity in the linear smoothing under this draft HCR when different sardine control parameters apply west/south of Cape Agulhas)

10 Draft Two-Area Harvest Control Rules for OMP-13 Thank you for your attention


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