Red King Crab Research Articles

Reproductive potential of red king crab (Paralithodes camtschaticus) across warm and cold stanzas in Bristol Bay in southwestern Alaska: Supplementary Figure

Reproductive potential of red king crab (Paralithodes camtschaticus) across warm and cold stanzas in Bristol Bay in southwestern Alaska: Supplementary Figure

Reproductive potential of red king crab (Paralithodes camtschaticus) across warm and cold stanzas in Bristol Bay in southwestern Alaska

Reproductive potential of red king crab (Paralithodes camtschaticus) across warm and cold stanzas in Bristol Bay in southwestern Alaska

Successful large-scale and long-term kelp forest restoration by culling sea urchins with quicklime and supported by crab predation

In 2013, a large scale (70 hectare) kelp forest restoration experiment was conducted in a sea urchin barren that had been stable for 45 years. We used 200 tons of quicklime to eradicate the sea urchin population. Kelp recovered within a year in the lime-treated sites. Quickliming did not significantly affect the abundance of non-target species. Mobile kelp fauna colonized the restored kelps, but at a slower rate than kelp and other macroalgae, probably due to slower dispersal abilities. The monitoring period (2012–2021) encompassed the expansion of invasive red king crabs, which emerged as a novel predator of sea urchins. This led to a gradual decline in sea urchin populations and facilitated kelp recovery also in the control sites. This delayed recovery does not invalid the conclusions of the short-term efficiency of the quicklime treatment, but it makes it difficult to conclude about the long-term effects. The study shows that quickliming can initiate kelp recovery within large urchin barrens. We postulate that the recovery of kelps outside the limed areas was due to crab predation, and that successful kelp restoration in areas with recruitment of sea urchins depends on a persistent top-down control of the urchins.

The spatiotemporal standardization of the stock index and reduction of hauls in research surveys (on the example of red king crab in the Barents Sea)

The paper presents the results of the spatiotemporal standardization of the stock biomass index of red king crab in the Russian EEZ of the Barents Sea carried out using the generalized additive mixed effect model (GAMM) which was implemented in the sdmTMB library of the Renvironment. The spatiotemporal approach used in species distribution modelling within GAMM enables taking into account numerous environmental factors and fishing gears, thereby increasing the quality of the assessment especially in areas with data shortage. Additionally, in modelling the stock density for areas with no observations the space-time autocorrelation in between hauls is also taken into consideration.

Dynamics of the age composition of the red king crab males in the Barents Sea with account of probability molt

The aim of the research was improvement of the algorithm of age determination for red king crab males in the Barents Sea, by taking into account the molting probability.Materials were the data of research surveys and fisheries monitoring obtained in 2001–2022 and combined in 54 data sets, as well tagging data published in open press.As results the previous algorithm which allowed establish the age composition of the red king crab males catches was improved. The parameters of the model of the dependence of the probability of molting on the width of the carapace, which was established earlier according to the tagging data, were changed. The modified model allowed to improve the adequacy of the estimates by reducing the values of the approximation error. Compared to the previous estimates of the age composition, the account of the probable molting history did not lead to a significant revision of the results: all noticeable generations remained the same as before, the time for recording a generation in catches however increased from 10 to 12 years. The parameters of the proposed model are the closest to those for the Kikhchik subpopulation of the red king crab off the Western Kamchatka. The contradiction associated with the discrepancy in the assessment of the maximum age of both the generation and individual specimens is discussed.Practical value. The obtained results can be applied for the red king crab stocks assessment with the help of cohort models.

Structure and long-term changes of polychaete communities of the Varanger fjord in 2003 and 2019

Long-term changes in species composition, production indicators, and structure of polychaete communities for the period of 2003 and 2019 in the Russian part of the Varanger fjord (Barents Sea) were shown. The connection of such changes with climate factors and the influence of the red king crab are considered. The changes in species composition, structure, and production characteristics of polychaetes in the Russian part of the Varanger fjord (Barents Sea) in 2003 and 2019 are shown. The linkage between these changes and the climatic factor, as well as the influence of the introduced red king crab Paralithodes camtschaticus (Tilesius, 1815), is discussed. The results demonstrate an increase in the quantitative characteristics of polychaete Spiochaetopterus typicus M. Sars, 1856, indicating a decrease in pressure from the king crab on bottom communities. The biodiversity indices indicate the absence of negative changes in the settlements of polychaetes in the Varanger fjord during the studied period.

Search for new materials based on chitosan for the protection of cultural heritage

Microorganisms are a significant cause of damage to cultural heritage, including paintings. Currently, the palette of antiseptics that are used in painting has narrowed considerably. This is due to the increased demands placed on such substances. It was shown that low molecular weight chitosan (LMWC) obtained from the king crab (Paralithodes camtschaticus) exhibits high activity against dominant fungi-destructors of paintings in the State Tretyakov Gallery. Nevertheless, the increasing market demand for chitosan has prompted the exploration of alternative sources. Insects, notably the bioconverter black soldier fly (Hermetia illucens), stand out as one of the most cultivated options. This study investigates the effectiveness of chitosan, isolated from H. illucens by a novel method developed by authors, in inhibiting fungi that damage tempera paintings. The activity of 33 and 39 kDa chitosans from H. illucens is comparable to the most active chitosans previously studied from P. camtschaticus. However, there are characteristic differences between these compounds, as shown by the results of FTIR spectroscopy, which may affect their consumer properties when used in paint materials. Our studies suggest that LMWC from H. illucens is a promising material that can expand the range of antiseptics used in painting.Graphical

Impact of Biotic and Abiotic Factors on Epibiotic Communities of the Barents Sea Red King Crab

Impact of Biotic and Abiotic Factors on Epibiotic Communities of the Barents Sea Red King Crab

Predicting the distribution of red king crab bycatch in Bering Sea flatfish trawl fisheries

Declining Bristol Bay red king crab (BBRKC) abundance has triggered recent closures of this iconic Bering Sea fishery and raised interest in bycatch in non-directed fisheries as a possible conservation concern. One particular concern is the effectiveness of static closed areas for bycatch fisheries in an era of climate warming and widespread distribution shifts. However, spatial data for supporting management decisions concerning bycatch is lacking, as fisheries-independent data are collected only in the summer, and the relationship to BBRKC distribution in the fall/winter/spring, when most bycatch occurs, is unknown. We filled this information gap by using fishery-dependent data to build predictive models of BBRKC bycatch distribution in non-pelagic trawl groundfish fisheries in the data-poor seasons. We trained Boosted Regression Tree models for bycatch occurrence and abundance of four BBRKC sex-size/maturity categories, and evaluation metrics indicated good to excellent predictive ability across all models. We found that flatfish directed-fishery CPUE, summer survey CPUE for BBRKC and flatfish, and depth were important predictors for bycatch occurrence and abundance. Physical variables (ice cover and temperature) were generally less important. We also found strong correlations between the mean latitude of observed bycatch and the summer survey for BBRKC, highlighting the ability of summer survey data to predict non-summer bycatch distributions. BBRKC bycatch prediction is a tractable problem, and our results are the first step towards operating models that may be used to evaluate proposed management actions. We also conclude that northward shifts in fishery-independent and -dependent data suggest the possible value of reassessing decades-old static closure areas for managing BBRKC bycatch.

Development of Fecundity of Red King Crab during Its Acclimatization in the Barents Sea

Development of Fecundity of Red King Crab during Its Acclimatization in the Barents Sea

On the prospects of fishery of the Barents Sea red king crab within the coastal waters of Russia

Objective: to review the current state of the red king crab stocks in the Barents Sea off the coast of the Kola Peninsula and propose options for optimizing their use.Method: the work is a review of the state of stocks, biology and fishing regime of the red king crab in the Barents Sea coast, based on previously published research results. In addition, unpublished survey data with appropriate explanations were used.Novelty: the review contains information relevant for the summer of 2023 on the fishing regime of the red king crab in coastal waters, examines the prospects for the exploitation of stock of king crab in connection with changes in legislation that occurred in 2023.Results: the coast of the southern part of the Barents Sea is of high importance for the reproduction of the red king crab population and can be considered as a reserve for its fishing in the EEZ of Russia. Among all the sections of the Barents Sea coast, Varanger-Fjord, as the most remote from the area of modern fishing area, is promising for the resumption of crab production in it. In addition, fishery the red king crab in the western part of coast of the Barents Sea will provide additional data on the impact of fishing on the stock, which will be used in fisheries management. In the near future, it is advisable to consider the possibility of changing the by-catch limit for non-commercial individuals when mining in the coastal area, as well as the possibility of allocating the Varanger-Fjord the red king crab as a separate management unit within a single reserve. Prior to receiving new data, it is possible to recommend that no more than 0.6 thousand tons of the red king crab in the Varanger-Fjord area.

Rapid and non-destructive quantification of meat content in the legs of live red king crab (Camtschaticus paralithodes) by near-infrared spectroscopy

Red king crab (RKC) is one of the most widely distributed and well-known of all king crabs. The edible meat of the RKC is in the legs and claws and is considered a delicacy. Occasionally, the content of meat is low, and this is regarded as the single most negative quality attribute. In this study, we elucidated how rapid and non-destructive near-infrared spectroscopy (NIRS) on live RKCs can be used to predict the meat content in the cooked legs. A NIRS prototype (wavelength range 760–1080 nm) was used to obtain spectra from the interior tissue of the crab legs. 99 live crabs (380 legs) were measured over a 10-month period. Calibration models were developed with a prediction error for meat content of 6.4 %-points, which is accurate enough to classify the crabs into low (<80 %) and high meat content. The amount of cooked meat is proportional to the amount protein in the muscle. A limitation with the method is that it may overestimate the meat content if the legs have lost free water due to e.g. injuries in the exoskeleton. The technology described can facilitate a more sustainable RKC fishery and improve the subsequent trade and processing.

Morphology, processing attributes, fatty acid, and amino acid composition in cooked leg meat and raw hepatopancreas of juvenile male red king crab (Paralithodes camtschaticus) after 12 months of live holding

This study investigated how diet composition (DC) (i.e., raw shrimp or dry feed alone and combinations thereof) affected the morphology, processing attributes, fatty acid (FA)- and amino acid (AA) composition in cooked leg meat and raw hepatopancreas of juvenile red king crabs (RKCs). After 12 months, the crab weight nearly doubled, and the average mortality was 10%. The DC influenced the attributes of the cooked leg meat and the raw hepatopancreas. In addition, crumbling the dry feed led to reduced nutritive conditions, especially in the 80 and 100% dry feeding groups. In the leg meat, the main FA components were PUFA, MUFA, and SFA in descending order, while for the raw hepatopancreas, the corresponding order was MUFA, PUFA, and SFA. Minor AA variations across the groups were observed in the cooked leg meat and raw hepatopancreas. A PCA revealed a grouping of selected morphological-, processing attributes, and FAs according to the 20 and 100% dry feed groups. This study did not explore the specific feed intake. Hence, whether the results reflect the DC, a lower feed intake due to the crumbling, or a combination is unknown. Overall, the results show positive prospects for live holding of juvenile RKCs.

Estimation of pop-up satellite archival tag initial surface position: applications for eastern Bering Sea crab research

BackgroundClimate change is reshaping Bering Sea crab distributions and recent population declines have elevated the urgency in understanding spatial dynamics in relation to management boundaries. While pop-up satellite archival tags (PSATs) can provide fishery-independent movement information, a high level of spatial resolution is needed to evaluate small-scale (i.e., 10 s of km) movements of crabs. Because PSATs drift at the surface prior to acquisition of a satellite-estimated location (via Argos), the accuracy of pop-up location (i.e., animal terminal position) estimates depends on the ability to accurately estimate drift error. We deployed PSATs (n = 36) on fixed-position moorings in Bristol Bay and Marmot Bay, Alaska to validate a new method to estimate tag pop-up location and an associated error ellipse that uses in situ drift data from surfaced tags to estimate drift error. Estimated pop-up location was compared to the location of tag surfacing (i.e., the tag’s fixed position) and to an alternative estimate (i.e., an early satellite-estimated location). Additional tags were deployed on mature male red king crab (Paralithodes camtschaticus) in Bristol Bay during 2020 (n = 84) and 2021 (n = 90) to compare estimates of tag drift error and crab displacement derived using the method.ResultsFor red king crab tags with pop-up location estimates in 2020 (n = 79) and 2021 (n = 46), mean drift error was 9% and 44% of mean crab displacement, respectively. For fixed-position PSATs with pop-up location estimates (n = 27), mean distance between the estimated pop-up location and the tag’s fixed position was 2.0 km, representing a mean improvement in accuracy of 51% over alternative estimates. Corresponding error ellipse estimates either encompassed the tag’s fixed position (n = 11) or their boundaries were a mean distance of 1.3 km (n = 16) from the fixed position.ConclusionsOur method improves pop-up location estimates for PSAT-tagged animals and is particularly well suited for crabs and other slow-moving benthic marine species. The improved estimates enhance PSAT utility for addressing management and ecological questions that require a fine spatial resolution, such as movement near management boundaries or defining essential habitat for important life history events.

Narrowed gene functions and enhanced transposon activity are associated with high tolerance to ocean acidification in a juvenile subarctic crustacean

Ocean acidification (OA) threatens marine crustaceans, particularly those at high latitudes where conditions are rapidly changing. Red king crab (RKC) support important fisheries in Alaskan waters. RKC early life stages are sensitive to OA when exposure occurs as embryos and juveniles. However, in a supporting study, RKC were surprisingly tolerant of varying OA conditions (pH 7.5, 7.8, &amp; 8.0) when reared long-term from larval hatching to the first crab stage (C1). Here, we examined gene expression in the C1 juveniles to characterize transcriptional activity of these OA-tolerant crabs. Expression of nearly half of all genes (44%) correlated with OA treatment, suggesting a strong molecular response to OA, contrary to the phenotypic results. Downregulated functions were numerous in response to OA, and included reduced energy production, biosynthesis, immune function, and notably lipid and carbohydrate metabolic processes, which suggest a shift in metabolic strategy to protein catabolism, possibly to reduce CO2 production and facilitate acid/base regulation. Only a handful of functions were enriched in OA-induced genes, which were related to transcription regulation, control of growth and cell death, and signaling activity. Transposon activity was high in OA-reared crab, many of which were upregulated at consistent levels, suggesting that transposon mobilization may be a component of the RKC OA-response system. Genetic composition did not differ among OA treatments indicating that transcriptional differences in OA-reared crab were more likely attributed to phenotypic plasticity than selective mortality. Our results suggest that OA-reared RKC have a narrowed, possibly optimized, set of gene functions that enables OA-tolerance through the early juvenile stage. OA-exposure from hatch may benefit RKC and related species by “hardening” them against OA through physiological reprogramming. Future studies should test OA-hardened crabs in additional challenges, as metabolic and immune limitations may ultimately make them more vulnerable to infection or secondary stressors.

Investigation of biofluorescence produced by the red king crab Paralithodes camtschaticus

AbstractBiofluorescence is widely documented in marine organisms, yet few studies exist for decapods. After observing the king crab Paralithodes camtschaticus biofluoresces, we carried out studies on two separately maintained groups of male crabs under controlled conditions. Hyperspectral imaging on Group 1 (n = 18) examined the exoskeleton, whereas fluorospectrometry examined the hemolymph of Group 2 animals (n = 19). Both groups were investigated for fluorescence signals before and after exposure to a live shipping transportation simulation. The spines, chelae, eyestalks and cervical grooves of the cardiac region of P. camtschaticus fluoresce in the green spectra (∼500 nm), while the arthrodial membranes of the joints fluoresce in the red spectrum (∼680 nm). After the shipping simulation, we observed a significant decrease in fluorescence in the eyestalks (p = 0.009), while the cervical grooves showed a less significant change (p = 0.01). The hemolymph examined with 21 excitation wavelengths (250–350 nm) emitted fluorescence in ∼400–550 nm spectrum. We found a significant increase (p &lt; 0.05) in fluorescence for 16 excitation wavelengths after transport simulation. The results presented in this study indicate that king crab fluorescence changes due to external stimuli. Fluorospectroscopy or hyperspectral imaging technology may serve as an effective early indicator of preclinical stress in these commercially important decapods.

Optimizing release strategies for red king crab stock enhancement: Effects of release timing

Red king crab, Paralithodes camtschaticus, was commercially important around Kodiak, Alaska, USA, in the 1960s and 1970s; however, the stock crashed in the late 1970 s and has remained closed since 1983. The lack of recovery inspired consideration of stock enhancement through the release of hatchery-reared juveniles as a means to bolster the wild population. We examined the effects of release timing on in situ survival of hatchery-reared red king crab by releasing juveniles in June, August, and September 2015 in Trident Basin, Kodiak. We monitored densities inside and outside of release plots for six months using quadrat counts to determine loss and emigration rates. Relative predation risk was determined using tethering experiments performed after each release, and predator densities were quantified using quadrat counts and predator transect counts. Initial mortality over the first 24 h was approximately 53%, and subsequent mortality rates decreased with month-of-release, likely due to a combination of larger size-at-release and seasonal changes in predation. Although predator density was consistent over time, relative predation risk of tethered crabs decreased with season, suggesting later releases may be beneficial. However, the extended hatchery rearing period needed for later releases presents other challenges, including cannibalism, and the potential for developing maladaptive traits. Stock enhancement programs must balance these trade-offs to maximize overall success. Early releases of small juveniles immediately after settlement may be optimal if large-scale hatchery communal rearing results in significant juvenile production loss and/or hatchery conditioning is impractical.

Mercury content in commercial crustaceans of the Barents Sea

This study aims to identify the total mercury content in the muscle and hepatopancreas of the main commercial crustaceans from the Barents Sea.The material for this study was the samples of red king crab Paralithodes camtschaticus and northern shrimp Pandalus borealis caught during the research cruises conducted by “PINRO” from 2012 to 2022. This study examines the samples of muscle collected from crustaceans, as well as the samples of hepatopancreas collected from the red king crab.Novelty: This study involves abundant data that was used to make the first comparative analysis of the Hg concentration in red king crab and northern shrimp. A significant similarity in the levels of Hg content in the muscle of shrimp and crab at the mean level was shown. The paper provides maps of average Hg content in the studied species for the entire Barents Sea.Methods used: the total mercury content in the samples was estimated by flameless atomic absorption spectroscopy analysis using Shimadzu Cold Vapor Atomic Absorption Spectrophotometer (Japan). Statistical data processing and charting were done using MS Excel and application software package of Statistica 13.Results: The paper shows that the average concentration of Hg in the muscle and hepatopancreas of the studied hydrobionts did not exceed 0.2 mg/kg of wet weight that is the acceptable concentration established by sanitary standards. The content of Hg in the red king crab’ hepatopancreas was about 2 times higher than in the muscle. The paper makes an assumption on the species-specifity of Hg content in the red king crab’ muscle. The Hg content in the muscle of P. borealis is strongly related to its fattiness. The paper suggests calculated background levels of the total Hg concentration in the muscle of P. camtschaticus and P. borealis from the Barents Sea.Practical relevance: The results obtained were used to establish the safety compliance of commercial crustaceans with the requirements adopted in Russia.

Fatty Acids in the Eggs of Red King Crabs from the Barents Sea.

The red king crab, Paralithodes camtschaticus, was introduced into the Barents Sea where, after a period of 30 years of adaptation, it has established a new population. This population has been commercially exploited over the past two decades, supporting profitable fisheries in both Russia and Norway. Biochemical studies aimed at assessing fatty acid profiles have been conducted, focusing primarily on the edible parts of red king crabs. Only recently have by-products been included in this research. Capture of female red king crabs is prohibited in Russia but is allowed in Norway. The fatty acids of the egg masses carried by these females have not yet been studied. To fill this knowledge gap, we assayed the fatty acid composition of eggs using gas-liquid chromatography. Our results showed a predominance of polyunsaturated fatty acids, while the concentrations of saturated and monounsaturated fatty acids were similar. Multivariate comparisons showed no significant differences in fatty acid profiles in terms of egg developmental stage (nauplius vs. metanauplius), habitat conditions (soft vs. hard bottoms), female size class, or number of autotomized limbs. However, individual comparisons showed some differences in fatty acids, the most important being the lower content of docosahexaenoic acid in eggs at the metanauplius stage compared to eggs at the nauplius stage, which is likely due to its essential role in the development of red king crab embryos. The total fatty acid content (53.94 mg g-1) was 2-87 times higher in eggs than in other red king crab tissues, confirming the critical role that fatty acids play in maintaining physiological processes during vitellogenesis. The high content of essential fatty acids and an optimal omega-3-to-omega-6 ratio (4.9) suggest that red king crab eggs are a good product for a healthy diet and a valuable source for extracting essential fatty acids.

First Record of Sarsia tubulosa (M. Sars, 1835) (Cnidaria, Hydrozoa) on Red King Crabs in the Coastal Barents Sea

Sarsia tubulosa (M. Sars, 1835), a colonial hydrozoan of the family Corynidae, is common in the Barents Sea. This study provides new evidence that the species acts as an epibiont of the red king crab Paralithodes camtschaticus, a non-indigenous but remarkably abundant decapod crustacean of immense commercial value in the coastal regions of the sea. This finding adds to the current collection of identified epibionts on the red king crab and highlights the prospect of ongoing symbiotic relationships between the crab and the regional fauna. We also provide photographic evidence of S. tubulosa colonies and a comparative morphological evaluation with another closely related corynid, Coryne hincksi Bonnevie, 1898, previously found on the red king crab. The main differences between these two species are the location of the gonophores (reproductive organs) on the hydranths and the final stage of their development: in the form of free-floating medusae (S. tubulosa) or remaining sessile as sporosacs (C. hincksi). Other distinguishing features include variations in hydranth morphology, number and arrangement of tentacles, and structural development of gonophores.