574 
Fishery Bulletin 99(4) 
Location of survey stations in Bristol Bay (east of 163.5° west longitude) visited during 1983 OCSEAP 
studies (A), 1985 OCSEAP studies (B, open squares), and by Stevens and Macintosh in 1991 (B, closed 
circles). 
Try nets had a headrope length of 5.4 m and either wooden 
or aluminum doors measuring 0.4 m wide x 0.9 m tall. The 
rock dredge was constructed of a rigid steel frame with a 
mouth opening 0.9 m wide x 0.4 m tall. The 1985 survey 
was conducted from 19 July to 2 August, nearshore (gen- 
erally inside the 50-m isobath), along the north Aleutian 
Shelf from Unimak Pass through the Port Moller region 
(Fig. 2B) also with try net and rock dredge. The 1991 
survey (Stevens and Macintosh 4 ) was conducted from 26 
May to 1 June along the North Aleutian Shelf from Port 
Moller to Kvichak Bay (Fig. 2B) with a 3.1-m wide beam 
trawl. The carapace length (CL) of all red king crab cap- 
tured in the above surveys was measured and recorded 
onboard the vessels. 
For each sampling period, length-frequency histograms 
were constructed to identify individual age classes (co- 
horts) within the data. Male and female crabs were pooled 
because sex-specific growth rates are not apparent until 
reproductive age (Weber, 1967; Dew, 1990), and the com- 
bined length-frequency data were analyzed by using the 
FiSAT software package (Gayanilo and Pauly, 1997) to de- 
termine the mean size (±1 SD) for each identifiable cohort. 
FiSAT employs a combination of Bhattacharya’s method 
(Bhattacharya, 1967) and NORMSEP (Hasselblad, 1966; 
Pauly and Caddy 5 ) to decompose complex size-frequency 
distributions into a series of best-fit normal curves that 
represent each cohort within the data set. In our study, the 
“mean size” of a cohort refers to the mean (±1 SD) of its 
associated best-fit normal curve, as determined by FiSAT 
size-frequency decomposition. 
5 Pauly, D., and J. F. Caddy. 1985. A modification of Bhat- 
tacharya’s method for the analysis of mixtures of normal dis- 
tributions. FAO Fisheries Circular 781, Sales and Marketing 
Group, Information Division, FAO, Viale delle Terme di Cara- 
calla, 00100 Rome. 
Postsettlement age, in Julian days, was then calculated 
for each cohort. For each year’s length-frequency histo- 
gram, the cohort with the smallest mean CL was assigned 
age 0, and the subsequent sizes assigned age 1 and age 2 
(Fig. 3). The age of each cohort (in days) was calculated as 
the time from settlement in the cohort’s settlement year 
until the median sampling date for the survey period. Set- 
tlement was estimated to be 15 July of each year because 
numerous 2-mm-CL individuals occurred in late July dur- 
ing the 1983 surveys, and a carapace length of 2 mm is 
typical of the first benthic instar (Kurata, 1961; Donaldson 
et al., 1992; Loher and Armstrong, 2000). Postsettlement 
age was plotted against the associated mean CL and two 
growth curves were fitted to the data. The first curve was 
a seasonalized version of the von Bertalanffy growth mod- 
el obtained from Anastacio and Marques (1995), where 
growth in carapace length is expressed as 
-[irxZ?xU-q M , ( )+Cx(iCxZ)/2n)xsin2mxU-t i )]T'^ ^ (-jq 
The second curve was a seasonalized Gompertz model, 
where growth in carapace length is expressed as 
L t =L max [e- e ~ {K "' 
where (in both models) L t = 
^ max ~ 
t = 
^ min ~ 
carapace length at time t; 
maximum carapace length; 
given time; 
time at which the carapace 
length is the minimum size 
for the life-stage of interest (in 
this case, minimum size for 
benthic red king crab=2 mm); 
