386 Fishery Bulletin 118(4) 
The currently adopted state HCR is HR15, 
with a maximum exploitation rate of 15% and a 
0.25 catch proportion cap on abundance (num- 
ber) of legal-sized males. An alternative HCR is 
HR10, with a maximum exploitation rate of 10% 
and a 0.25 catch proportion cap on legal-sized 
male abundance; HR15U is an alternative HCR 
with a maximum exploitation rate of 15% with- 
out any cap on the proportion of legal-sized male 
abundance that can be caught, HR30 is an alter- 
native HCR with a maximum exploitation rate of 
30% and a 0.25 catch proportion cap on legal-sized 
male abundance, and HRO is a reference HCR 
with no directed fishery (i.e., zero exploitation 
5 + Steepness=0.729 
MMB35=6602 | 
No. of recruits (millions) 
MMA aye=5-45 
5000 rate) (Table 1, Fig. 1, Suppl. Fig. 1 [online only]). 
MMB (t) The state HCR is based on MMA and computes 
the catch proportion for year t, HR,, as follows: 
Figure 3 
The stock—recruitment relationship from the Ricker model fitted to the : 
stock and recruitment data for golden king crab (Lithodes aequispinus) i eta ae 
in the eastern Aleutian Islands during 1981-2018. The vertical dashed HR, = | sills | if 0.25MMA,,,<MMA,<MMaA,,,, and (6) 
lines indicate the respective reference points: 35% of the unfished level MMA.y< 
of mature male biomass (MMB,,;), which is a proxy for biomass cor- 0 if MMA,«<0.25MMA,,., 
responding to maximum sustainable yield, and average mature male 
abundance (MMA,,,,). The steepness value is the estimate for 2018. In 
the operating model used in this analysis, catch per unit of effort is 
assumed to be proportional to selected abundance. t=metric tons. 
where x = the maximum exploitation rate; and 
MMaA,,,. = the average MMA during 1985-2018. 
ave 
The exploitation rate from Equation 6 is con- 
verted into an instantaneous fishing mortality 
over the predicted catches in weight by source of mortal- rate (F, in year t) by solving this equation: 
ity, in other words, by using this equation: 
m f{~, a ae F. x ge x 
OFL, =¥i(c jj + D', jwjt+Tr ol03)> (4) HR, == =e * (7) 
t 
where the prime symbols indicate that the catch 
and bycatch are calculated by using F=F'op, 4. 
The ABC (which applies to all sources of fishery- 
related mortality) is calculated (NPFMC, 2018) 
with this equation: 
ABC, = 0.75 x OF L,. (5) 
SY 
a 
State harvest control rule options We compared 
5 candidate state HCRs, with the aim to main- 
tain consistency with state of Alaska commercial 
fishery regulations, the Alaska Board of Fish- 
eries policy on king and Tanner crab resource 
management (ABF”), the North Pacific Fishery 
Management Council fishery management plan 
(NPFMC!), and National Standards 1 and 2 of 
the Magnuson-Stevens Fishery Conservation 
and Management Act (NPFMC!). The candidate 
HCRs were informed by catch policies for other 
stocks of king crab species in the Bering Sea and 
No. of recruits (millions) 
1990 2000 2010 
Year 
Aleutian Islands, historical exploitation rate esti- 
mates for the fishery for golden king crab in the 
Aleutian Islands, and stakeholder input. 
? ABF (Alaska Board of Fisheries). 1990. Policy on king 
and Tanner crab resource management. Policy no. 90- 
04-FB. [Available from website.] 
Figure 4 
The number of recruits of golden king crab (Lithodes aequispinus) 
in the eastern Aleutian Islands for 1981-2019 estimated with the 
stock assessment model. The gray shaded area indicates the 95% con- 
fidence interval. In the operating model used in this analysis, catch 
per unit of effort is assumed to be proportional to selected abundance. 
