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Refining the FXP (fixed proportion) CMP

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posted on 01.04.2021, 12:49 by Doug Butterworth, Rebecca A Rademeyer
Various refinements to the FXP CMP are considered to attempt to improve its resource conservation performance in particular. For the “100 tuning” variant (Br30 = 1 for both Eastern and Western stocks for deterministic projections of OM1), either or both stocks can be rendered (near) extinct for some OMs. The OMs that lead to the greatest conservation difficulties for these CMPs have a low abundance scale for the Western stock, especially those that also incorporate the R3 scenario where a regime shift occurs in the future. Introducing two modifications to the CMP – a linear decrease in the fishing proportion and allowance for greater than 20% decreases in TACs when the aggregate abundance index drops below a threshold for the area concerned – considerably improves conservation performance for the Eastern stock. However, some problematic R3-scenarios OMs remain when considering conservation performance for the Western stock. Placing a cap on the East area TAC can assist marginally in that respect, but also introduces some associated disadvantages. Suggestions are made for additional areas of investigation to refine the performance of this CMP further.



Department of Mathematics and Applied Mathematics, University of Cape Town