. The Eastern Bering Sea Shelf : oceanography and resources / edited by Donald W. Hood and John A. Calder . Figure 61-14. Distribution of the Tanner crab (Chionoe- cetes opilio) in tiie eastern Bering Sea. Darkly shaded portions indicate areas of consistently high abundance. however, it is not yet clear whether these differences are caused by genetic or environmental factors. Nevertheless, C. bairdi in the eastern Bering Sea has been considered a single stock for management purposes. From the distribution of various size-groups of males and females in 1979 (Otto et al. in press), it appears th
. The Eastern Bering Sea Shelf : oceanography and resources / edited by Donald W. Hood and John A. Calder . Figure 61-14. Distribution of the Tanner crab (Chionoe- cetes opilio) in tiie eastern Bering Sea. Darkly shaded portions indicate areas of consistently high abundance. however, it is not yet clear whether these differences are caused by genetic or environmental factors. Nevertheless, C. bairdi in the eastern Bering Sea has been considered a single stock for management purposes. From the distribution of various size-groups of males and females in 1979 (Otto et al. in press), it appears that large male and female C. opilio are found on the southern and southwestern fringes of the habitat (Fig. 61-14) and that juveniles are con- centrated in northern and central areas. It may be that C. opilio found north of St. Lawrence Island are not self-sustaining. For example, data contained in Wolotira et al. (1977) show that only percent of 7,061 females examined were carrying eggs in Norton Sound and the Chukchi Sea. The scarcity of egg-bearing females in the Norton Sound area was also observed in 1979. Elsewhere in the Bering Sea, the mean size at which 50 percent of the female population is ovigerous was between 42 and 50 mm carapace width (Somerton 1975, Macintosh et al. 1979). Wolotira et al. (1977) found that only percent of 1,397 females of CEirapace width larger than 50 mm were carrying eggs. Concentrations of large males are found in widely differing localities from year to year. For example, Pereyra et al. (1976) found that large male C. opilio (>110 mm carapace width) were about evenly distributed north and south of 58°N latitude in 1975, but 1979 data showed only 6 percent of this size group north of 58°. It seems probable that there is one extremely large population of C. opilio in the eastern Bering Sea, displaying localized areas of abundance that are geographically unstable with time. For the purpose of fishery management, C. opilio in the east
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