Siddeek et al.: Development of harvest control rules for hard-to-age crab stocks 
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The 5 HCRs were ranked within each conservation and 
economic performance criteria leading to a risk matrix 
that involved grouping these performance metrics into 3 
categories: conservation, catch, and catch stability. Overall 
ranks within each category were based on average ranks 
across all criteria. 
Results 
Performance of harvest control rules (scenario 1) 
The time trajectories of MMB and MMA for scenario 1 
(i.e., the best estimates of the parameters when CPUE 
was assumed to be linearly proportional to selected abun- 
dance; Suppl. Table 1 [online only]) stabilized toward the 
end of the 30-year projection period in median terms for 
the 5 HCRs. As expected, HR10, HR15, HR15U, and HR30 
led to much lower MMB and MMA than HRO. The alter- 
native policy of HR30 resulted in slightly lower MMB (Fig. 
2, A and C) and MMA (Fig. 2, B and D) than HR10, HR15, 
20 30 
HCR — HR10 
Effort (no. of pot lifts) 
Q 
= 
= 
fe) 
Q 
— 
fo} 
fe} 
S 
i 
L 
= 
Ww 
and HR15U, with the latter 2 HCRs having very similar 
trajectories of MMB and MMA. The MMB and MMA tra- 
jectories remained above MMB,, and MMA,,,, respec- 
tively, throughout the projection period when the 
simulation started above MMB,, and reached the respec- 
tive reference points toward the end of the projection 
period when the simulation started in an overfished state 
(Fig. 2). The estimates of MMB and MMA are qualita- 
tively similar, a result that was expected given MMB is 
MMA multiplied by average weight, which did not change 
much over time. The results are similar for scenario 1 
when CPUE was assumed to be proportional to the square 
root of abundance (Suppl. Tables 7—9) (online only). 
Catch and effort stabilized (in median terms) toward 
the end of the 30-year projection period for HR10, HR15, 
HR15U, and HR30. However, the time trajectories of 
catch and effort differed depending on the initial state. 
The median catch declined over time when MMB, 1, was 
greater than MMB,, (Fig. 5A) but increased over time for 
when MMB, 9,3 was equal to 0.5MMB,, (Fig. 5C). Effort 
was almost constant over the projection period when 
20,000 
~- HR15 --- HR15U -- HR30 
Figure 5 
Median catch and median effort of the directed pot fishery for golden king crab (Lithodes aequispinus) in the 
eastern Aleutian Islands under 4 harvest control rules (HR10, HR15, HR15U, and HR30), with the initial 
state of the stock set at (A and B) healthy or (C and D) overfished, for scenario 1 of the operating model in 
which a linear relationship between catch per unit of effort and selected abundance is assumed. Values are 
based on a 30-year projection period that begins with 2018. The stock is projected from 2 initial levels of 
abundance, measured in mature male biomass (MMB): a healthy state (i.e., MMBo,./MMB,,=1.55, where 
MMB; is MMB in 2018 and MMB,, is 35% of the unfished level of MMB) and an overfished state (i.e., 
MMB 4;:/MMB;;=0.50). Data used in the model are for golden king crab in 1981-2018. For details about the 
harvest control rules, see Table 1. t=metric tons. 
