Aspects of growth, reproduction, distribution and abundance of the jonah crab, (<i>Cancer borealis</i>) Stimpson, in Norfolk canyon and the adjacent slope 378 views

<i>Cancer borealis</i> was found to be contagiously distributed on the continental shelf and upper slope in Norfolk Canyon and the adjacent slope in depths of 47-500 m and temperatures of 5.0-15.4°C. Maximum abundance was observed betweenl50° and 350 meters and 6.0-ll.9°C, Female crabs were more abundant than males at depths less than 150 m and males more abundant in deeper water. Male <i>C. borealis</i> attain a larger size than do females. Molting takes place throughout the year for small crabs but larger crabs molt less frequently in winter than during the remainder of the year, Male crabs appear to become sexually mature at a long carapace width of 90-100 mm as do females although maturity may be reached at a smaller size for females. <i>C. borealis</i> mates throughout the summer and fall with a peak in late summer, Spawning appears to take place in late winter and early spring. Morphometric analysis revealed changes in the growth rate of abdomen and carapace of female <i>C. borealis</i> at 80-90 mm long carapace width. No such changes were observed in the males. 

MA (Master of Arts)

Jonah crab; Crabs

English

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1978-01-01