582 
Fishery Bulletin 99(4) 
Males Females 
1976 year class 1976 year class 
1990 year class 1990 year class 
40 60 80 100 120 40 60 80 100 120 
Carapace length (mm) 
Figure 7 
Best-fit normal curves, as determined with FiSAT, of the length-frequency modes associated 
with male and female red king crabs of the 1976 (solid curves) and 1990 (dashed curves) 
year classes, from age 3.9 to 6.9, demonstrating the divergence in size-at-age between the 
two year classes. In particular, note the large difference in apparent molt increment dis- 
played by the year classes between ages 3.9 and 4.9. All curves have been standardized to 
a uniform height in order to facilitate their comparison, because the number of crabs that 
were observed differed between years. 
peratures during the early 1980s, and moderate tempera- 
tures from the mid-1980s through the late 1990s. 
Discussion 
Our analyses demonstrate that Bristol Bay red king crab 
grow slower than previously assumed. The present stock- 
recruitment relationship used to manage this population is 
based on growth models (Weber, 1967; Balsiger, 1974; Ste- 
vens and Munk, 1990) that suggest a time lag of six years 
between settlement and subsequent recruitment (i.e. seven 
years after fertilization), where reproductive recruitment is 
defined to occur at ~97 mm and -105 mm CL for females 
and males, respectively (Zheng et al., 1995a, 1995b). Our 
results indicate that mean age at full reproductive recruit- 
ment is likely 8-9 years after settlement. Crabs that settled 
in 1990 began to reach reproductive size in 1997, at 7 years 
after settlement, and at this age only -50% of the individu- 
als were at or above the reproductive size cut-off; the mode 
did not become fully recruited for an additional 1 to 2 years. 
Individuals of the 1976 year class grew even slower and, on 
average, were still slightly smaller than reproductive size 
at 8 years after settlement. This year class would not have 
begun to contribute substantially to the reproductive stock 
until at least 9 years after settlement. 
The discrepancy between our estimates of mean age- 
at-recruitment and presently accepted values is due in 
part to incorrect assumptions of the latter regarding the 
growth of early juveniles in Bristol Bay. Weber (1967) con- 
ducted one of the few comprehensive in situ studies of ear- 
ly juvenile size-at-age in Alaskan waters and clearly dem- 
onstrated that red king crab should be expected to reach 
a mean CL = -66 mm CL three years after settlement. 
This conclusion contrasted sharply with earlier data from 
Bristol Bay that showed strong size modes with means of 
4 mm, 9 mm, and 17 mm CL in early summer samples 
in 1956, 1957, and 1958, respectively (Fisheries Agency of 
Japan 6 ), apparently representing the modal progression of 
the 1956 year class, and suggesting a much slower growth 
rate. More recent studies conducted in Kodiak (Dew, 1990; 
Donaldson et al., 1992) have supported Weber’s (1967) 
conclusions; thus, the observations made by the Fisheries 
Agency of Japan 6 have been largely ignored. Our results 
suggest that the data from Kodiak is in good accord with 
Weber’s (1967) conclusions, but that mean CLs of 4 mm, 
Fisheries Agency of Japan. 1959. Report of research on king 
crab in the eastern Bering Sea. Int. N. Pac. Fish. Comm. Annu. 
Rep., p. 71-78. [Available from Secretariat, North Pacific Anad- 
romous Fish Commission, Suite 502, 889 West Pender Street, 
Vancouver, British Columbia, V6C 3BC.] 
