Siddeek et al.: Development of harvest control rules for hard-to-age crab stocks 
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Figure 7 
The probability of (A-D) catch and (E—H) catch per unit of effort (CPUE) being below their mean values for the period 
after crab stocks were rationalized, from the 2005-2006 fishing season through the 2018-2019 fishing season, in the 
directed pot fishery for golden king crab (Lithodes aequispinus) in the Aleutian Islands, by model scenario, under harvest 
control rules (HCRs) HR10, HR15, HR15U, and HR80. Estimates are based on the last 10 years of a 30-year projection 
period for 53 scenarios of an operating model used to evaluate HCRs. The stock is projected from an initial level of abun- 
dance, measured in mature male biomass (MMB): 1.55MMB,,, where MMB,, is 35% of the unfished level of MMB. In the 
model used in this analysis, a linear relationship between CPUE and selected abundance is assumed. For details about 
the HCRs, see Table 1. 
Discussion 
We have demonstrated the utility of the simplified MSE 
for evaluating HCRs through consideration of conserva- 
tion and economic trade-offs. Our results indicate that 
HR15 and HR15U are preferable to HR10 and HR30, 
given the desire to balance the trade-off between sus- 
tainability and economic viability, and this notion was 
supported under both the linear and nonlinear assump- 
tions about the relationship between CPUE and selected 
abundance. Although HR30 yielded the highest catch, it 
performed poorest in terms of other economic and con- 
servation criteria. Specifically, HR30 had the highest rel- 
ative probabilities of MMB being below MMB,, and of 
MMA being below the historical average MMA, had the 
lowest CPUE, and required substantially more effort to 
realize marginally higher (~2% higher) catches compared 
with HR10, HR15, and HR15U. Relative to HR10, HR30 
required 69% more effort to achieve 17% more catch 
(Table 5). Therefore, criteria beyond projected average 
TAC are important from an economic viewpoint because 
costs required to make excessive numbers of fishing 
trips when fishing effort is high may outweigh modest 
increases in TAC. 
Although we suggest that HR15 is the optimal HCR, 
given the trade-offs between conservation, catch, and 
catch stability, we acknowledge that the preferred HCR 
may differ depending on management and stakeholder 
priorities. Although HR10 yielded improved performance 
in terms of some conservation and economic criteria 
(e.g., higher CPUE, MMA, MMB, and reduced effort), 
it yielded lower catch compared with that from HR15, 
HR15U, and HR30. Our analysis is meant to provide 
managers and stakeholders with a tool to evaluate the 
trade-offs between various fishery management criteria 
relative to risk. 
The conservation and economic criteria were very simi- 
lar for HR15 and HR15U. Although the catch limit on 
legal-sized male abundance did not meaningfully affect 
the performance of the management strategy, it is likely 
