380 
National Marine 
Fisheries Service 
NOAA 
Abstract—The golden king crab (Lith- 
odes aequispinus) has_ traditionally 
been managed in the Aleutian Islands 
by using a constant catch strategy but 
interest in abundance-based manage- 
ment has emerged with the recent adop- 
tion of a size-based stock assessment 
model. Management strategy evalua- 
tion (MSE) is commonly used to quantify 
conservation and economic trade-offs of 
alternative management strategies, but 
computational constraints can impede 
the representation of all sources of 
uncertainty. We conducted a simpli- 
fied MSE for the golden king crab that 
focused on what we regarded as the 
major uncertainties, including initial 
stock abundance, future recruitment, 
estimation of mature male biomass 
and abundance, and catch implementa- 
tion error, while capturing the existing 
unique federal and state cooperative 
management framework for crab stocks 
in the Bering Sea and Aleutian Islands. 
The simplified MSE identified recruit- 
ment variability as the most important 
factor in determining overall fishery 
performance, and conservation and eco- 
nomic metrics highlight benefits of a 
15% over a 30% exploitation rate. We 
feel this simplified approach results in 
a robust analysis despite the reduced 
computational demands compared with 
those of a full MSE. Similar approaches 
can be used for other stocks, but manag- 
ers must define management objectives, 
consider stock dynamics, and identify 
factors likely to have the greatest effect 
on expected performance. 
Manuscript submitted 15 March 2020. 
Manuscript accepted 7 December 2020. 
Fish. Bull. 118:380—398 (2020). 
Online publication date: 30 December 2020. 
doi: 10.7755/FB.118.4.7 
The views and opinions expressed or 
implied in this article are those of the 
author (or authors) and do not necessarily 
reflect the position of the National 
Marine Fisheries Service, NOAA. 
Fishery Bulletin 
@ established in 1881 << 
Spencer F. Baird 
First U.S. Commissioner 
of Fisheries and founder 
of Fishery Bulletin 
Development of harvest control rules for 
hard-to-age crab stocks: the example of the 
golden king crab (Lithodes aequispinus) in the 
eastern Aleutian Islands in Alaska 
Shareef M. Siddeek (contact author)! 
Benjamin Daly? 
André E. Punt? 
Steve Martell* 
Jie Zheng' 
Mark Stichert? 
Email address for contact author: shareef.siddeek@alaska.gov 
' Division of Commercial Fisheries 
Alaska Department of Fish and Game 
P.O. Box 115526 
Juneau, Alaska 99811 
* Division of Commercial Fisheries 
Alaska Department of Fish and Game 
351 Research Court 
Kodiak, Alaska 99615 
Strategies for calculating catch limits 
have evolved from the use of constant 
catch, constant exploitation rate, and 
fixed escapement to a focus on thresh- 
old harvest control rules (HCRs). The 
latter are considered superior because 
they include limits and targets for sizes 
of the stock and modify exploitation lev- 
els to rebuild stocks to, or sustain them 
at, healthy levels (Quinn et al., 1990; 
Zheng et al., 1993; Caddy and Mahon, 
1995; Restrepo and Powers, 1999; Punt 
et al., 2008). However, it is necessary 
to specify parameter values for HCR 
formulas (for HCRs, see Figure 1 and 
Supplementary Figure 1 [online only]) 
because each set of parameter val- 
ues will lead to different outcomes. 
Management strategy evaluation (MSE) 
is becoming an increasingly common 
tool for quantification of trade-offs 
among conservation and economic goals 
for management strategies (Punt et al., 
2016). Management strategy evaluation 
involves identifying management objec- 
tives, identifying the key uncertainties 
and representing them in a mathematical 
model of the system (hereafter referred 
to as the operating model), identifying 
3 School of Aquatic and Fishery Sciences 
University of Washington 
P.O. Box 355020 
Seattle, Washington 98105-5020 
* Sea State Inc. 
9401 NE Tidal Court 
Bainbridge Island, Washington 98110 
the candidate management strategies 
(the combination ofa method for estimat- 
ing stock status and an HCR), projecting 
the population forward in the operating 
model for each candidate management 
strategy, and summarizing the results 
through the use of performance metrics. 
Because MSE is computationally inten- 
sive, addressing all major uncertainties, 
including modeling, estimation, observa- 
tion, process, and implementation, can 
be impractical. As such, if MSE is to be a 
practical management tool, it must accu- 
rately represent the management frame- 
work and narrow sources of uncertainty 
down to a key subset and represent them 
in the operating model. Here, we describe 
how to employ MSE in a simplified form 
in a unique federal and state cooperative 
management framework, using the stock 
of golden king crab (Lithodes aequispi- 
nus) in the eastern Aleutian Islands as 
an example. The data-poor nature and 
complexity of the assessment of this stock 
necessitated employment of a simplified 
MSE in which the stock assessment pro- 
cess is simulated stochastically rather 
than modeled explicitly (for a similar 
approach, see Punt et al., 2008). 
