cantly different than 0.50 (Z = 7.8, P^s 0.001). 

 Sex ratio, however, was not homogenous between 

 trap sets (x^ = 137.5, P^ 0.0001), indicating that 

 the sex of each specimen was not independent 

 of other specimens but highly correlated. Thus, 

 females tended to be caught with other females 

 and males tended to be caught with other males. 

 Segregation by sex is also commonly observed for 

 P. camtschatica (pers. obs.). 



Although the sexes of crabs within each set are 

 correlated, the hypothesis of a 0.50 proportion 

 male in the population can still be tested if each 

 set is assumed to be an independent random 

 sample. The test is made by calculating a t- 

 statistic from the mean and variance of the pro- 

 portion male within individual trap sets. Because 

 the number of crabs within each set varied con- 

 siderably, the mean proportion was calculated as a 

 weighted average, with the weighting factors 

 equal to the number of crabs in each set (Cochran 

 1943). The ^test was not significant (t = 0.396, P 

 = 0.86); thus, a 1:1 sex ratio is not rejected. 



Female Reproductive Condition 



The number of female L. couesi in each of the six 

 categories of reproductive condition is shown as a 

 function of size in Figure 3. Eighty-six percent 

 of the females examined were mature ( categories 

 3-6). Virgin females had partially developed 

 ovaries and appeared to have never spawned 

 previously. Assuming virgin female L. couesi 

 require the same length of time to complete 

 maturity as "pubescent" female P camtschatica 

 (Powell et al. 1973), their first spawning will occur 

 soon after their next molt in the following spring. 



Mature female L. couesi display more hetero- 

 geneity in their reproductive condition than fe- 

 male P. camtschatica. This is exemplified in the 

 following table, where the percentage of mature 

 female L. couesi in each of the four mature 

 reproductive categories is compared with the 

 equivalent reproductive categories of female P. 

 camtschatica collected in the eastern Bering Sea 

 at the same time as the seamount survey. 



FISHERY BULLETIN: VOL. 79, NO. 2 



25r completely hatched eggs 



^\ hatching eggs 



CO 

 OQ 



< 



CE 

 O 



OC 

 LU 



m 



25r virgin 



25r immature 



60 80 100 



CARAPACE LENGTH (mm) 



120 



Although no distinction was made between devel- 

 262 



Figure 3. — Number of female Lithodes couesi by 2 mm size 

 intervals in each of the six categories of reproductive condition 

 described in the text. 



oping and hatching eggs for P camtschatica, it 

 is evident that P. camtschatica had nearly com- 

 pleted spawning and were carrying new eggs, 

 whereas L. couesi had not completed spawning 

 and were carrying eggs in a variety of develop- 

 mental stages. 



If L. couesi are similar to P camtschatica in 

 spawning soon after hatching the previous clutch, 

 then the heterogeneity in their reproductive con- 

 dition can be interpreted in either of two ways. 

 First, L. couesi were sampled midway in their 

 spawning season; therefore, the maturing eggs 

 hatch later in the season. Second, L. couesi were 

 sampled at the end of the spawning season; 

 therefore, the maturing eggs are from spawning 

 in the current season and hatch in the succeed- 

 ing year. The difference in these interpretations 



