Fishery Bulletin 118(4) 
HRO HR10 
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Figure 8 
The probability (A-E) of mature male abundance (MMA) being less than average MMA (MMA,,,.) and (F—J) of mature male 
biomass (MMB) being less than 35% of the unfished level of MMB (MMB,,;) for golden king crab (Lithodes aequispinus) in the 
Aleutian Islands during the period from the 1985-1986 fishing season through the 2018-2019 fishing season, by model scenario, 
under harvest control rules (HCRs) HRO, HR10, HR15, HR15U, and HR30. 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 
abundance: 1.55MMB,,;. 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. 
an important conservation component of the management 
strategy given the desire to ensure future recruitment. 
Realized exploitation rates on abundance of legal-sized 
male golden king crab is expected to be higher when pop- 
ulation abundance is on an increasing trend (i.e., when 
mature male recruits have yet to reach the legal size) 
because the exploitation rate is scaled to MMA. The maxi- 
mum exploitation rate on legal-sized male abundance pro- 
vides an additional level of protection against overfishing 
of legal-sized males in years when legal-sized male abun- 
dance is low relative to the abundance for the entire size 
range of mature males and is a commonly adopted step in 
the HCRs for other crab stocks in the Bering Sea and 
Aleutian Islands (e.g., red king crab in Bristol Bay; Pen- 
gilly and Schmidt’; Zheng et al., 1997). 
* Pengilly, D., and D. Schmidt. 1995. Harvest strategy for Kodiak 
and Bristol Bay red king crab and St. Matthew Island and 
Pribilof blue king crab. Alaska Dep. Fish Game, Spec. Publ. 7, 10 
p. [Available from website.] 
It is important to note that our simulations limited 
the catch in the directed fishery by the retained catch 
component of the ABC. As such, the more aggressive 
HCRs likely performed more conservatively (i.e., there 
was zero probability of exceeding OFL and ABC) than 
any of the HCRs that did not constrain the directed 
fishery catch below the retained catch component of the 
ABC. However, our simulations best approximate how 
management for crab stocks occurs in the North Pacific 
Ocean because TACs would not be set above estimated 
ABCs in practice. 
Incorporating uncertainty is a fundamental challenge 
in MSE. Parameters, such as natural mortality, catch- 
ability, growth, maturity, selectivity, and the stock— 
recruitment relationship are assumed to be correct and 
time invariant, and the projections ignore spatial and 
environmental variability (Somerton and Otto, 1986; 
Hollowed et al., 2001; Clark and Hare, 2002). However, 
the ability to use MSE to help achieve management goals 
depends on how well uncertainty in the system is repre- 
sented in simulations (Punt et al., 2016). Because it is 
