Results for the first few robustness tests for the hake OMP2018 review

Ross-Gillespie, Andrea; Butterworth, Doug S

Results for the first few robustness tests for the hake OMP2018 review

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2018-10

Abstract

Results for six robustness tests are presented, where the tests were conducted for the RS02 Reference Case (RC) model. The robustness tests assume (1) no future surveys, (2) all future surveys are conducted by industry vessels, (3) future surveys take place every second year only, (4) the RC with an undetected increase of 2% p.a. in commercial catchability in the future, (5) no future surveys with this same undetected increase in catchability and (6) use of the old Algorithm 2013 species splitting algorithm. Assuming no future surveys has the biggest impact, with a marked reduction in TAC and increased inter-annual variation. However, if this CMP is retuned so that the risk is the same as the RC CMP, then the resulting TAC projections are in fact very similar to the RC – therefore this retuning would be an important exercise to conduct if it is known that future surveys will be less frequent or absent. Simulations suggest that the remaining robustness tests have relatively little impact on projected resource status and catches; even an undetected increase in commercial catchability, though resulting in lower future biomasses, does not seem too serious a concern as the lower 5%ile of biomass after 25 years remain above BMSY for both species.

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