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Fishery Bulletin 94(2), 1996 



tances of 200 km, Somerton, 1981a), the 

 constancy of size at maturity over the lati- 

 tudinal range of C. tanneri is remarkable. 

 Such constancy has been documented be- 

 fore (Tester and Carey, 1986) and has been 

 attributed to the uniformity of water tem- 

 perature over great distance at the depths 

 inhabited by this species. For C. angulatus, 

 the observed estimates of W 50 (Figs. 5 and 

 6; Table 1 

 C.japonicus in the Sea of Japan. 



were similar to values of W so for 



Size at maturity 



Estimates of the carapace width at 509c maturity, 

 W 50 , for both male and female C. tanneri (Figs. 5 and 

 6) were not significantly different from reported val- 

 ues of W 50 off Oregon (Table 1). Likewise, the esti- 

 mate of the mean carapace width of mature individu- 

 als. W , for females was not significantly different 

 from the estimate of W m for Oregon, but the esti- 

 mate of male W was significantly smaller than the 

 estimate for Oregon (Table 1). Although there may 

 be a slight change in size at maturity from Oregon 

 to the Bering Sea, compared with the large spatial 

 variation in size at maturity observed for the shal- 

 low-water species C. bairdi and C. opilio on the 

 Bering Sea shelf ( W changes by up to 1 19c over dis- 



Reproduction 



Fecundity of C. tanneri did not increase 

 significantly with carapace width (P=0.89, 

 n=29; Fig. 7), primarily because of the 

 large variability in fecundity at size. Over 

 the carapace widths sampled (83-113 

 mm), mean fecundity was 86,500 eggs. 

 Fecundity of C. angulatus displayed much 

 less variability and increased significantly 

 with carapace width (fecundity = -65,608 + 

 1,664 x CW, P<0.001, # 2 =0.55, n=24). For 

 C.japonicus, Ito ( 1976) reported that 70-mm 

 females have about 40,000-50,000 eggs, ap- 

 proximately the same as the fecundity pre- 

 dicted for C. angulatus at the same size (Fig. 

 7). Mean egg diameter was 0.75 mm 

 (SE=0.04) for C. tanneri and 0.74 mm 

 (SE=0.04) for C. angulatus. Although these 

 estimates are not significantly different from 

 the estimates reported for C.japonicus ( 0.68 

 mm, Ito, 1976; 0.74 mm, Fukutake, 1965), 

 they are significantly larger than the esti- 

 mates reported for both of the shallow-wa- 

 ter species C. bairdi (0.56 mm ) and C. opilio 

 (0.66 mm, Haynes et al., 1976). 



Most mature females of both species 

 carried eggs in the same stage of development (Table 

 2); therefore it appears that both species have syn- 

 chronous and seasonal reproduction, in other words, 

 all reproductively active females mate and extrude 

 eggs at about the same time of year. Seasonal repro- 

 duction has been previously reported for C. tanneri 

 (Pereyra, 1966; Jamieson et al., 1990) and C.japonicus 

 (Ito, 1976). However, it has also been reported that C. 

 japonicus has a 2-year reproductive cycle (Ito, 1976) 

 and therefore does not have synchronous spawning. If 

 this is true for either C. tanneri or C. angulatus. one 

 would expect to find more heterogeneity in the observed 

 stages of egg development, unless our macroscopic 

 evaluation of reproductive condition failed to detect 

 differences in embiyonic development between the first 

 and second year of a 2-year cycle. 



