Data on correlation between the claw height (CH) and carapace width (CW) of the males of the crabs Chionoecetes from the Okhotsk and the Bering seas are evaluated. The coefficient of morphometric maturity (K%) is suggested for division of morphometrically mature and immature males. K% is calculated as percent relation of the CH to CW. The boundary value which allows divide mature and immature males with the probability more than 95% is equal to 16 for C. bairdi and C. angulatus. For the majority populations of the snow crab C. opilio (West Kamchatka, the Northern part of the Okhotsk Sea, East Sakhalin, Navarin area of the Bering Sea) it is equal to 21, while for 2 populations (the Central part of the Okhotsk Sea; Koryaksky area of the Bering Sea) it is equal to 19. It is proposed that immature males of the snow crab become physiologically mature when K% exceeds 14, and they become morphometrically mature while it exceeds 20. Correlations between morphometrically maturity, hemolymph biochemistry and muscle development are discussed. The general pattern of the snow and tanner crabs males growth with account of alternatives in the age of both physiological and morphometric maturities and terminal molt is proposed.

Based on the materials of two trawl surveys (1997 and 2000), two trap surveys (1992 and 2001) and 153 fishing trips (1992–2007), the distribution of snow crab Chionoecetes opilio in the northern part of the Okhotsk Sea was analyzed. A functional structure of the snow crab area was compiled on materials of distribution of size and gender groups supplemented by literature data. The center of the structure is reproduction zone — dense accumulations of females with eggs deposited on pleopods or already released larvae, located near the edge of the shelf. The pelagic larvae settled down in the upper part of the shelf, the zone at depths of up to 100 m, where the fry grows up to 2 years, after which they descend deeper into the zone of non-migrating juveniles. In this zone the crabs become mature and start ontogenetic migration towards the reproductive zone. During the migration the females pass terminal molt, mate and come in the reproductive zone with laying on pleopods eggs. Females live up to 6 years after terminal molt. Terminal molt of males occurs gradually, in small portions of total males. Over molted males slow down and stop migration. During the period from maturity to terminal molt, several molts of growth can pass. As a result, some males after the terminal molt remain in the zone of migration, part in the reproductive zone, part follow the feeding zone of commercial males, where the terminal molt occurs. This zone is the main fishing area. These males return to the reproductive zone shortly before death, 3–4 years after the terminal molting. This structure reduces the negative role of cannibalism in the early stages of development.

Spatial distribution of the Barents Sea snow crab (Chionoecetes opilio) in the Russian Exclusive Economic Zone (EEZ) and the high seas (the Loophole) was analyzed basing on the data collected using commercial fishing traps during the fishing seasons 2013, 2014, 2016 and 2017. Functional groups of the snow crab population were distinguished in compliance with allometric growth patterns and the terminal moult phenomenon of Chionoecetes species. Available data have enabled us to reveal spatial distribution of morphometrically mature males (MM) and morphometrically immature males (MI) as well as mature and immature females. Distribution patterns of mentioned functional groups visualize allocation of following population units: reproductive area, foraging area of MM and MI males, non-sterile eviction area and sterile eviction area. All these population units as well as the foraging area of early instars and the larvae settling area are allocated within the Russian EEZ. The Loophole covers mainly the peripheral area of the Barents Sea snow crab population. Only a small northeastern part of the Loophole covers the foraging area of MM males. Results of implement study show that the core of the Barents Sea snow crab population is allocated within the Russian continental shelf in the Barents Sea. Only the western periphery of the snow crab population, which apparently belongs to non-sterile and sterile evictions areas, extends beyond the Russian continental shelf.

In recent decades the snow crab (Chionoecetes opilio) has been spreading in the eastern part of the Barents Sea and the adjacent areas of the Kara Sea. Hydrological conditions for most of the Barents Sea are very close to optimum for the snow crab, there are large areas of suitable habitat and abundant sources of food. Therefore, better understanding of trophic interactions between the snow crab and native benthic fauna is important to assess any potential impacts on the ecosystem and to enable the rational management of fisheries resources in the eastern Barents Sea. This paper investigates the snow crab diet and its feeding intensity in the Barents Sea. Data shows that the snow crab has very wide ration that includes almost all kinds of benthic invertebrates in the Barents Sea. There is a difference in the diet of females and males, juveniles and adults. Juveniles and females prefer shallow areas with communities of bivalve mollusks, males live deeper on slopes and depressions where polychaetes and crustaceans are the most abundant group. Stomach contents are analyzed to determine the species composition and the frequency of occurrence for various benthic taxa. Consumption of food was estimated and compared with data from the Russian seas of Pacific region. Total annual grazing of macrozoobenthos by the snow crab is calculated for its current distribution in the Barents Sea. Snow crab consumes at least 30 thousand tons of benthos annually, which amounts to 0.1–0.2% of the total macrozoobenthos biomass of the investigated area. Population of the snow crab provides the largest impact on the benthic communities in the north-eastern part of the Barents Sea and near the south side of the Novaya Zemlya Archipelago.

Abundance, sex ratio and size composition of the red King crab in pot lines catches on the fishing grounds in Russian waters of the Barents sea have been analyzed during the period from 2003 till 2016. All data have been standardized and stored in the ‘Bioresouce’ Data Base (VNIRO). CPUE (crabs per pot) and size composition of males and females have been analyzed separately for each year and fishing ground. Two research areas (Western and Eastern area) were defined on the basis of fishing effort distribution. Each area has its own spawning and nursery ground. Long-term analysis revealed periodicity in appearance of abundant crab generations in Western and Eastern areas once in every 4–5 years. The growth, migrations and fishery exploitation of each abundant generation has been analyzed. The cumulative contribution of each abundant crab generation to the total catch of the Red King crab in the Barents Sea was assessed. The impact of legal and IUU fishery on the abundance and life duration of different generations was discussed. Each abundant generation first appear in the Western research area and then emerge in the Eastern research area.

In this study we analyze a spatial distribution and abundance of red king crab Paralithodes camtschaticus (Tilesius 1815) in different seasons in the semi-enclosed bay by diving observations. The study was performed in Zelenaya Inlet, which is a small fjord type bay, protected from waves by a shallow sill and 2 small islands on the entrance. The abundance of red king crab in Zelenaya Inlet ranged from 0,17 to 1,8 ind./100 m² in August 2015, and between 0,34 and 4,17 ind./100 m² in May 2018. Average abundance was found to be 4 times higher in May than in August. We suppose that this difference in crab abundance is related to migration and redistribution of crab in the I nlet, but not to an actual population increase. Inside the Inlet mostly juveniles were found, on the outer transect only mature females were present in August, and both mature females and males occurred in May. Our data support a hypothesis that semi-enclosed bays are very important for red king crab reproduction in the Barents Sea and indicate possible sources of error in estimates of red king crab abundance due to migrations and different behavior in different seasons.

Aspects of the size composition of the Barents Sea red king crab in the coastal part of Murman and the Kanin Peninsula following the studies of the traps in 2008–2017 were analyzed. Calculations performed using the criterion of Smirnov λ and the clustering Ward’s method, show heterogeneity of the size composition of males and females in crab aggregations in different parts of the Russian territorial sea. The study resulted in 6 groups of the red king crab identified: one is found almost along the entire coast and the rest are confined to certain areas. It is shown that the composition of the spatial groups allows identifying features of the crabs’ clusters in different parts of the coastal area and the dominant size and functional group in clusters of invertebrates. The Varanger-fjord with a relatively small bottom area has 5 of 6 groups, including a group of males which occurs only in its waters. There is a separate group of females with external eggs, occupying a vast area of shallow waters along the Kanin coast of the “Voronka” of the White Sea. In 2008–2017 group formation of crabs and their division into smaller groups were observed in the Varanger-fjord. The groups in the Varanger-fjord can be defined as formed with a stable replenishment. The data obtained suggest that all groups of red king crab in the Varanger-fjord can be isolated from the Barents Sea population of this invertebrate.

The study of the community of organisms associated with the red king crab was undertaken in Dalnezelenetskaya Bay (Barents Sea) in July 2012. A total of 44 taxa of associated species were found on crabs. The total prevalence of infestation was 84,5%. The frequency occurrence of attached animals was relatively low. The highest levels were found for bryozoans and gastropods (5,1%). Among mobile organisms the amphipods Ischyrocerus commensalis (84,5%), the harpacticoid copepods Tisbe furcate (74,1%) and Harpacticus uniremis (29%) were the most abundant. In addition, relatively high prevalence was registered for the fish leech Johanssonia arctica (22,4%). The comparison of prevalence data of 2012 with the levels of 2011 revealed significant differences in case of the polynoid polychaetes Harmothoe imbricata which were more abundant in 2012 and for the amphipods Ischyrocerus anguipes which were more abundant in 2011. The prevalence of symbionts in large crabs were 2,5 times higher than in immature crabs. Similar pattern was found for the total number of associated species per one crab. Localization patterns of common species were studied.

A technological scheme for growing red king crab juveniles in a modular basin complex was developed. Seven stages were included: “Catch and delivery of females with eggs” (1); “The content of females with eggs” (2); “The content of females in the period of larvae separation “ (3); “Growing of larvae” (4); “Growing postlatvae (glaucotoea) ” (5); “Growing juveniles” (6); “Release of juveniles in the natural environment” (7). The success of stages 1 and 2 depends on the physiological state of the females. The duration of stage 2 is determined by the stage of maturity of the eggs. In stage 3, a point light source located in the container compartment separated from the females by a perforated septum should be used to quickly harvest newly emerged larvae from eggs. Stage 4 is the most labor-intensive. In this phase of the red king crab life cycle, cannibalism appears, leading to an increase in mortality of larvae with a lack of food. At the stage 5 there is a transition of individuals from the plankton to the bottom way of life. In this regard, in the culture vessel, it is necessary to establish substrates for the settling of postlarvae (glaucotoea). Glaucotoea does not feed, at this stage of development of the red king crab feeding is not carried out. At stage 6, juveniles lead a bottom lifestyle. At this stage, it is necessary to perform a gradual replacement of the nets for settling glaucotoea on bottom substrates. The red king crab juveniles begin to feed, and for its feeding they use mixed fodders, and, to a lesser extent, nauplii of Artemia sp. At the final stage 7, it is necessary to prepare the juveniles for transportation and releasing into the natural environment in pre-selected locations. Application of the proposed biotechnical methods and approaches to the production and cultivation of the red king crab juveniles will allow to optimize the cultivation of the species, as well as taxonomically and ecologically related representatives of crabs.

The estimations of the physiological state of the red king crab Paralithodes camtschaticus and snow crab Chionoecetes opilio individuals on motor reactions based on the material collected in the Barents Sea was presented. This estimations can be used for determination of hydrobionts viability in the field, on shipboard, during the exposure at the basin complex and further transportation in live condition. It was find out that the set of markers is species-specific. The movement, motor activity of the walking limbs, antennules, limbs of the mouthparts and scaphagnatides were selected as markers for red king crab; and for snow crab — movement, motor activity of the walking limbs and limbs of the mouthparts, squeezing the pincers of the pereiopod under stimulation, the tone of the third pair of maxillipeds. Verification by biochemical hemolymph parameters of the method for visual estimation of viability was maked. The content of glucose, lactate, uric acid and total protein were used.

King crab (Paralithodes camtschaticus) most demanded fishing object as the crabmeat product is highly valuable delicacy with excellent qualities having a high nutritional and biological value. The paper presents an overview of the primary processing of crab catches, packaging and transportation in a living form for the purpose of implementation through retail chains and public catering. Describes the size-mass and chemical composition, food and biological value of crab muscle tissue.The relevance and efficiency of the integrated use of king crab due to additional product (biologically active substances — enzymes, lipids, attractants, chitin-chitosan, dietary supplements) of cutting waste from crab on the limb of walking and the cephalothorax from its contents were displayed. A perspective scheme of the technological process in the production of frozen unprocessed products in the conditions of the fishery, as well as food products and the whole complex of biologically active substances, which are an additional range of products with a high added value from the residue cutting Kamchatka crab, is presented.