We determined the size of sexual maturity of male and female blue crabs in the northwestern part of the sea (zone of cold core action), as well as in the northeastern part of the sea and the local cluster near the Iona bank (zone of comparatively warm waters). Morphological 50% maturation of males in the northwestern part of the Sea of Okhotsk was observed at the carapace width of 73.3 mm. Similar width were demonstrated for the northeastern part of the sea and for the Iona Bank area –

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... ely 88.5 mm and 91.0 mm. Females in samples from the northwestern part of the sea reached functional 50% maturity at the carapace width of 71.7 mm, from the northeastern part – of 79.4 mm, and from the Iona Bank – of 81.0 mm. Comparison with available literature data showed that blue crab in the northwestern part of the Sea of Okhotsk has probably the slowest growth rate, and the crabs have the smallest size at maturity compared to individuals in the other areas.