Results of the assessment of by-catch in the specialized fishery of target crab species are presented. The studies covered three fishing areas: off Western Kamchatka (Kamchatka-Kuril and West Kamchatka sub- zones) and off the southeastern coast of Kamchatka (Petropavlovsk-Komandorskaya subzone). In addition to the target object, the catches included both non-target species of crabs and representatives of other groups of animals: fish and invertebrates. The by-catch of fish included representatives of several genera, the most common being Pacific cod (Gadus macrocephalus), Irish lords (Hemilepidothus sp.) and snailfishes (Careproctus sp.). Among invertebrate representatives in the by-catch, octopuses (Octopus sp.) most often prevailed by weight in the fishery of red king crab (Paralithodes camtschaticus) off Western Kamchatka and Tanner crab (Chionoecetes bairdi) off Eastern Kamchatka.