Commercial Crab Species Research Articles

Состояние запасов и перспективы промысла крабов в подрайоне Центральная часть Охотского моря

Based on the materials of research in 2015 and 2018, data on the spatial distribution and biological state of crabs in one of the new fishing areas for the Russian Federation are presented - subregion 61.52 Central part of the Sea of Okhotsk. In the area studied, the following commercial crab species were recorded in crab trap catches: Lithodes aequispinus, L. couesi, Paralomis multispina, P. verrilli, Chionoecetes opilio and Ch. angulatus. A single capture of 2 individuals of the sharp-winged crab Oregonia bifurca, which had not previously been encountered in the Sea of Okhotsk, was noted. The main clusters of commercial species of crabs were confined to the northern site at depths of 300-500 m. Of the entire variety of species, only the equidistant crab forms dense aggregations, the stocks of which have been exploited by industry since 2017. Chionoecetes opilio and Ch. angulatus stocks in the area of «polygon» can also recruit the resource base of commercial fishing.

A scientometric review of climate change and research on crabs

Crabs categorized as cold-blooded organisms are especially at risk as climate change worsens. Their current situation was not well documented, especially in terms of scientometric analysis. The present study aims to investigate the relationship between research on crabs and climate change-related studies, with a focus on identifying trends and hotspots over time. The analysis was based on a collection of over 2834 relevant documents and 107,502 cited references indexed in the Web of Science Core Collection (WOSCC) database from 1977 to 2022. The findings indicated an increase in research in recent decades, with the USA as the largest contributor, followed by China and Brazil. Researchers from the USA and Germany were among the top published authors in the field. The most highly cited studies in WOSCC focused on the relationship between harmful algal blooms and crab research. Of these studies, 20 clusters were generated, with the most influential cluster identified as related to “ocean acidification,” “blue king crab,” and “mud crab fishery.” The most frequently cited and influential keywords in the field were “climate change” and “hypoxia,” respectively. Our conclusion is that the fields of “research on crabs” and “climate change” are thriving and that further exploration of the adaptation strategies of these organisms is necessary. This knowledge will benefit scientific communities, philanthropic funders or related governments, fisheries-related industries, and NGOs towards the sustainable management of commercial crab species in the future.

Geometric Morphometric Analysis of the Chinese Mitten Crab Eriocheir sinensis: A Potential Approach for Geographical Origin Authentication

AbstractThe illegal counterfeiting of the geographic origin label for Chinese mitten crabs Eriocheir sinensis is a major problem in China. More effective methods are needed for authenticating their geographic origin and increasing their commercial value. Therefore, a geometric morphometric analysis was conducted for the present pilot study to identify variation in Chinese mitten crabs from eight well‐known geographic areas in China: Gehu, Luoma, Gucheng, Liangzi, and Junshan lakes in the Yangtze River system; the Dongying area in the Yellow River system; and the Yingkou and Panjin areas in the Liaohe River system. Landmark coordinates were extracted by image processing after digitization of the carapace and the ventral region of the cephalothorax and were then analyzed using relative warp principal components methods, discriminant analysis, thin‐plate spline analysis, and grid distortion. Many of the type II landmarks used were extracted via relative warp principal components analysis, and they had the most important contributions to explaining the variation. The discriminant analysis indicated that the carapace of male and female crabs and the ventral region of the cephalothorax in males had geographical origin distinguishing rates of 100%. These results suggest that plasticity in shape exists for local adaptation of the ventral region of the cephalothorax and especially the carapace among Chinese mitten crabs from the different locations examined. Geometric morphometric analysis has potential for authenticating the important commercial crab species by authorized inspectors or scientists in markets or laboratories after further development of image processing, landmark extraction, shape morphometric databases, detection models, and geographical origin recognition.

Prospects of Red King Crab Hepatopancreas Processing: Fundamental and Applied Biochemistry

Since the early 1980s, a large number of studies on enzymes from the red king crab hepatopancreas were conducted. They have been relevant both from a fundamental point of view in terms of studying the enzymes of marine organisms and in terms of rational natural resource management aimed to obtain new valuable products from the processing of crab fishing waste. Most of these works were performed by Russian scientists due to the area and amount of waste of red king crab processing in Russia (or the Soviet Union). However, the close phylogenetic kinship and the similar ecological niches of commercial crab species and the production scale of the catch provide the bases for the successful transfer of experience in the processing of the red king crab hepatopancreas to other commercial crab species caught worldwide. This review describes the value of recycled commercial crab species, discusses processing problems, and suggests possible solutions for these issues. The main emphasis is made on hepatopancreatic enzymes as the most salubrious products of red king crab waste processing.

1H NMR metabolomic profiling of the blue crab (Callinectes sapidus) from the Adriatic Sea (SE Italy): A comparison with warty crab (Eriphia verrucosa), and edible crab (Cancer pagurus)

The metabolomic profile of blue crab (Callinectes sapidus) captured in the Acquatina lagoon (SE Italy) was compared to an autochthonous (Eriphia verrucosa) and to a commercial crab species (Cancer pagurus). Both lipid and aqueous extracts of raw claw muscle were analyzed by 1H NMR spectroscopy and MVA (multivariate data analysis). Aqueous extracts were characterized by a higher inter-specific discriminating power compared to lipid fractions. Specifically, higher levels of glutamate, alanine and glycine characterized the aqueous extract of C. sapidus, while homarine, lactate, betaine and taurine characterized E. verrucosa and C. pagurus. On the other hand, only the signals of monounsaturated fatty acids distinguished the lipid profiles of the three crab species. These results support the commercial exploitation and the integration of the blue crab in human diet of European countries as an healthy and valuable seafood.

Intra-guild predation among early benthic phase red and blue king crabs: Evidence for a habitat-mediated competitive advantage

The apparent shift in predominance of commercial crab species from blue king crab (Paralithodes platypus) to red king crab (Paralithodes camtschaticus) around the Pribilof Islands, Alaska, USA, may be driven by ecosystem-level processes such as competitive displacement or predation during early life stages. Specifically, intra-guild predation among species during the early benthic phase might be a source of mortality limiting blue king crab population recovery. In a laboratory experiment, we evaluated how varying ratios of prey species (year-0 blue and red king crabs) and habitat type (shell and cobble) affect prey preference of year-1 red king crabs. Year-0 red king crabs were preferentially consumed over blue king crabs in shell habitat, but not cobble, likely because the smaller interstitial spaces in shell reduced predator foraging efficiency and predator–prey encounter rates. Blue king crabs had high levels of crypsis regardless of habitat type or predator presence/absence, while red king crabs were less cryptic overall compared to blue king crabs, but crypsis increased when predators were present. Preference for red king crabs in shell may reflect divergent adaptations between species for minimizing predation. Blue king crab's light, mottled coloration and relatively smooth, flat carapace is well adapted for visual and physical crypsis in shell habitat, while the monochromatic, dark coloration and pronounced spination of red king crabs may make them more conspicuous. Our results show that habitat can mediate intra-guild predation between Paralithodes species and suggest that shell material may provide blue king crabs a competitive advantage over red king crabs. The extent of shell habitat may be an important factor regulating blue king crab distribution or the recovery of depleted populations around the Pribilof Islands.

Infestation of parasitic barnacle Sacculina spp. in commercial marine crabs.

Commercial crab species infected of rhizocephalan cirripedes are reported from the coast of Parangipettai. Sacculina spp. were collected from brachyuran hosts Portunus sanquinolentus, Portunus hastatoides, Chaybdis feriatus, Charybdis variegate, Charybdis natator, Charybdis miles, Charybdis lucifera, Charybdis hoplites, Charybdis hellerii, Charybdis granulate, Charybdis amboinensis and Thalamita coeruleipes respectively.

Diet and some ecological features of the most widespread commercial crab species in the northwestern Sea of Japan in early spring

Results of the study of feeding habits of the commercial crab species Chionoecetes opilio, Ch. japonicus, Paralithodes platypus, P. camtschaticus, and Erimacrus isenbeckii in early spring 2009 are presented. The composition, distribution, and quantitative characteristics of benthos in the areas of sampling are analyzed. The generalized pattern of distribution of the considered crabs is shown with the maximum and mean densities. These crabs were found to consume at least three to four single portions of food during 10–12 hours of daylight. The lowest feeding intensity was observed in the opilio snow crab in March and April. Cannibalism proved to be typical for all the studied crab species in the spring. It was most developed in the deepwater red snow crab, in whose diet representatives of the same species constituted a one-third share. It was also noted that the diet of the studied crabs included a major proportion of crabs and shrimps, which was unusual for the feeding habits of the same species in other Far Eastern seas.

The period of occurrence, density, and distribution of larvae of three commercial crab species in Peter the Great Bay, Sea of Japan

Based on materials from plankton surveys carried out in 2004–2009, the period of occurrence, density, and distribution of larvae of three commercial species of crabs in the Peter the Great bay and adjacent areas of Sea of Japan were studied. The larvae of the horsehair crab Erimacrus isenbeckii (Brandt, 1848) occurred in the plankton from mid-March to early June, within the range of water temperature from −1 to 10.8°C. The larvae of the helmet crab Telmessus cheiragonus (Tilesius, 1812) appeared in the plankton in mid-April and occurred to the end of June within the temperature range from 2.8 to 13.0°C. The larvae of the snow crab Chionoecetes opilio (O. Fabricius, 1788) appeared in the plankton in mid-April as well, but some individuals sporadically occurred until early August. All the species of crabs produced one generation of larvae for their reproduction season. The terms of larval stay in plankton depended on water temperature and the duration of the pelagic period increased in colder years. In that area, the larvae of C. opilio were the most abundant (up to 41 ind./m3) and the zoea density of horsehair and helmet crabs was significantly lower (no more than 2 ind./m3). The larvae of C. opilio occurred over the entire area of the Peter the Great bay; the greatest aggregations of their early stages were observed in its southwestern open part. The maximum density of E. isenbeckii zoea was recorded in the south of the Amursky bay and in the Posyet bay. Individual larvae of T. cheiragonus occurred in the Posyet bay and in the southern part of the Amursky and Ussuriisky bays. The late-stage larvae of all crab species were concentrated in areas of the coastal circulation.

Survival and behavioral responses of juvenile crabs of Cancer edwardsii to severe hyposalinity events triggered by increased runoff at an estuarine nursery ground

Estuaries represent highly dynamic environments, especially with respect to salinity. Exploitation of these habitats by marine species can assist their ecological success, however they require specialized behavioral strategies as well as physiological abilities to cope with the fluctuations of physical stressors. The Valdivia River estuary, southern Chile, is a site of high larval recruitment and juvenile abundance of the commercial crab species Cancer edwardsii, particularly during the spring and summer months. This estuary experiences severe low salinity events (< 7.5) for periods exceeding 6 h, that are associated with rainfall events and the subsequent higher flow rates of the tributaries. To determine the strategies employed by juvenile crabs living in the inner portions of the estuary in the face of changes in salinity conditions, we evaluated their survival and behavioral responses when exposed to a salinity gradient. Early juveniles were incubated at salinities of 0, 7.5, 15–22.5, 32 and crab mortality was recorded after 1, 6 and 12 h of exposure. In addition, early juveniles were experimentally exposed to continuous and gradual changes in saline conditions to evaluate their behavior, which was recorded on video. The main results were (1) despite most Cancer species being considered weak osmoregulators, 30% of individuals of C. edwardsii were able to survive freshwater conditions for 12 h. (2) burying and not quiescence behavior was associated with a drop in salinity, (3) in severe hyposaline conditions, the crabs increased their survival burying in the substrate, probably using higher salinity (> 22) interstitial water. Our findings suggest that burying behavior plays a key role in allowing the crabs inhabit inner estuarine areas where sudden and unexpected severe hyposalinity events occur.

Parasitism of the blue king crab, Paralithodes platypus, by the rhizocephalan, Briarosaccus callosus

The apparent shift in predominance of commercial crab species from blue king crab (Paralithodes platypus) to red king crab (Paralithodes camtschaticus) around the Pribilof Islands, Alaska, USA, may be driven by ecosystem-level processes such as competitive displacement or predation during early life stages. Specifically, intra-guild predation among species during the early benthic phase might be a source of mortality limiting blue king crab population recovery. In a laboratory experiment, we evaluated how varying ratios of prey species (year-0 blue and red king crabs) and habitat type (shell and cobble) affect prey preference of year-1 red king crabs. Year-0 red king crabs were preferentially consumed over blue king crabs in shell habitat, but not cobble, likely because the smaller interstitial spaces in shell reduced predator foraging efficiency and predator–prey encounter rates. Blue king crabs had high levels of crypsis regardless of habitat type or predator presence/absence, while red king crabs were less cryptic overall compared to blue king crabs, but crypsis increased when predators were present. Preference for red king crabs in shell may reflect divergent adaptations between species for minimizing predation. Blue king crab's light, mottled coloration and relatively smooth, flat carapace is well adapted for visual and physical crypsis in shell habitat, while the monochromatic, dark coloration and pronounced spination of red king crabs may make them more conspicuous. Our results show that habitat can mediate intra-guild predation between Paralithodes species and suggest that shell material may provide blue king crabs a competitive advantage over red king crabs. The extent of shell habitat may be an important factor regulating blue king crab distribution or the recovery of depleted populations around the Pribilof Islands.