Chionoecetes Research Articles

Comparative Analysis of Morphometric and Reproductive Parameters of Snow Crab (<i>Chionoecetes opilio</i>) of the Kara and Barents Seas

The paper presents a comparative analysis of size and reproductive parameters of snow crab in the Barents and Kara Seas, estimated in the period 2005–2019. In the Kara Sea, females reach maturity when their carapace width (CW) is over 30 mm, and the carapace width at 50% maturation is 38 mm. In the Barents Sea, female crabs reach functional maturity when their CW 35 mm, and the carapace width at 50% maturation is significantly higher compared to the Kara Sea and is equal to 51 mm. The fecundity of individuals of the same size, caught in the Kara Sea, is slightly lower than the fecundity of individuals recorded in the Barents Sea. At the same time, the increase in the number of eggs with an increase in CW in females of the Kara and Barents Seas is linear and statistically different (ANCOVA, p = 0.0327): 27 and 22 thousand eggs with an increase in CW by 10 mm, respectively. Compared to snow crabs in other geographic regions, in the Kara Sea, the values of the studied snow crabs parameters were close to the values estimated for individuals of the Arctic eastern seas: the Chukchi Sea and the Beaufort Sea. Most of the parameters of the Barents Sea population were comparable with the parameters of the populations of the southern part of the native range (the Sea of Japan, North-West Atlantic). It was revealed that the near-bottom temperature is to a large extent a limiting factor affecting not only the distribution of snow crab in the regions of the Northeast Atlantic, but largely determines the features of its morphometric and reproductive parameters during the acclimatization of the species in the Kara and Barents Seas.

A step towards the integration of spatial dynamics in population dynamics models: Eastern Bering Sea snow crab as a case study

Considering spatial processes in population dynamics models can be difficult because of data limitations and computational costs. We adapted a high-resolution spatiotemporal assessment framework to better address fine-scale spatial heterogeneities based on theories of fish population dynamics and spatiotemporal statistics. Specifically, we developed a size-based state-space model for the snow crab (Chionoecetes opilio) population in the Eastern Bering Sea (EBS) to refine the representation of spatial processes in integrated population models, facilitate understanding of the drivers of spatiotemporal population dynamics, and provide new insights for management advice. The model fits to spatial survey and fishery-dependent catch data. It implicitly accounts for seasonal movement between the time of the survey and that of fishery to estimate fine-scale spatial population dynamic and fishing impacts, including potential environmental drivers. We quantify, for the first time, spatiotemporal variation in exploitable abundance, fishing mortality, recruitment, and mature and immature abundance. The model estimated declines in exploitable abundance and in fishing mortality with variable spatial distributions, and sporadic recruitment, spatially concentrated in the northeast EBS. Few spatial assessments have been used as the basis for management advice and we consider this study as a step towards the integration of spatial dynamics in stock assessment.

The effect of variable light intensity in luminescent-netting pots on the catch of snow crab (Chionoecetesopilio)

The use of light in pots has been shown to increase snow crab catch rates in eastern Canada and the Barents Sea, where better fishing efficiency could result in less fuel consumption, and financial and ecological benefits. However, some light characteristics necessary for maximizing efficiency have yet to be researched. The purpose of this study was to determine if there is a change in catch per unit effort (CPUE; number of snow crab per pot) and size selectivity of snow crab with varying light intensity. Three types of experimental luminescent-netting pots were used, each type with a different level of light intensity via the amount of phosphorescent strands woven into the pot netting, (either 2-, 4-, or 6-strands) and were compared to the traditional pot used in the fishery. There were mixed results among treatments, with the 2-strand pot catching fewer snow crab <103 mm carapace width (CW) and more snow crab ≥103 mm CW than the traditional pots, but overall, had a lower CPUE for legal and sub-legal sized males (14.8 and 3.1 per pot, respectively) than the traditional (16.1 and 5.5 per pot, respectively) when considering all size classes. When compared to the traditional, the 4-strand pot caught more legal and sub-legal (CPUE of 18.8 and 8.0 per pot, respectively) snow crab in terms of CPUE but caught fewer commercial snow crabs from 95 to 98 and 103–113 mm CW. The brightest intensity pots (6-strand) showed no significant difference in CPUE or size selectivity in comparison to the traditional. Increased light intensity pots either had no effect on snow crab capture (6-strand) or produced unwanted results (loss of commercial sizes, increase in sub-legal sizes). Conversely, the 2-strand pot showed decreases in juvenile crab catch and increases in the catch of the most valuable size-classes observed, which are attractive results to fisheries managers and harvesters, respectively. These results, combined with a large price increase, suggest that higher light-intensity pots are not attractive for the commercial fishery.

Ghost fishing efficiency by lost, abandoned or discarded pots in snow crab (Chionoecetes opilio) fishery

Marine pollution by lost, abandoned or otherwise discarded fishing gear (ALDFG) often has negative impact on the ecosystem through plastic pollution and continuous capture of marine animals, so-called “ghost fishing”. ALDFG in pot fisheries is associated with high ghost fishing risk. The snow crab (Chionoecetes opilio) pot fishery is conducted in harsh weather conditions increasing the risk of fishing gear loss. Due to plastic materials used in the pot construction, lost gear can most likely continue fishing for decades. This study presents a method to quantify ghost fishing efficiency relative to catch efficiency of actively fished pots. On average, the ghost fishing pots captured 8.29 % (confidence intervals: 4.33–13.73 %) target-sized snow crab compared to the actively fished pots, demonstrating that lost pots can continue fishing even when the bait is decayed. Given the large number of pots lost each year, the ghost fishing efficiency is a considerable challenge in this fishery.

Snow crab (Chionoecetes opilio) hemocytes and hepatopancreas transcriptomes: identification, validation, and application of immune-relevant biomarkers of exposure to noise

The snow crab (Chionoecetes opilio) fishery off the east coast of Newfoundland and Labrador, Canada, has been impacted by annual seismic oil and gas surveying in recent decades, and commercial crab harvesters are concerned that it could potentially affect this resource. A laboratory study was performed to investigate the effects of chronic noise exposure on the transcriptomes of snow crab hemocytes and hepatopancreas, which are important in immunity, metabolism and response to environmental stress. Snow crab were held in replicate control or experimental tanks; on alternating days, the experimental tanks were exposed to noise from an underwater speaker which played a recording of a seismic airgun firing every 10 sec in a continuous loop for ~ 22 weeks (chronic noise). RNA sequencing was used to identify candidate noise-responsive molecular biomarkers in both hemocytes and hepatopancreas. The quantified transcripts of individuals (i.e. n=10 from each of the four groups) were compared using DESeq2, identifying over 300 noise-responsive transcripts in each cell/tissue type. Real-time quantitative polymerase chain reaction (qPCR) assays were designed and run for 61 of these transcripts with significant BLASTx hits. One transcript (rgs2) was significantly (p &amp;lt; 0.05) higher expressed in both hemocytes and hepatopancreas in response to noise; five and seven other transcripts were either significant or showed a non-significant trend of differential expression (0.05 &amp;lt; p ≤ 0.1) in hemocytes (e.g. cfb upregulated, sacs and myof downregulated) and hepatopancreas (e.g. gpx3 and atf3 upregulated, sult1c4 downregulated), respectively. To further investigate the performance and utility of these candidate biomarkers in the field, expression levels of 25 selected transcripts were then examined in the hepatopancreas of snow crab that had been subjected to 2D and 3D seismic surveying using both qPCR and multivariate statistical analyses. Overall, few of these biomarkers showed consistent results in field-collected snow crab, highlighting the need to combine lab and field-based studies to fully evaluate the utility of biomarkers. Nonetheless, our study still identified noise-responsive biomarkers in both settings (including stress and immune relevant genes), providing valuable information for understanding the impact of ocean noise on snow crab physiology and health.

Sequential Extraction of Valuable Bio-Products from Snow Crab (Chionoecetes opilio) Processing Discards Using Eco-Friendly Methods.

Green extraction methods using a combination of mechanical, enzymatic, and green chemical treatments were evaluated for the sequential extraction of carotenoid pigments, protein, and chitin from crab processing discards. Key objectives included avoiding the use of hazardous chemical solvents, conducting as close to a 100% green extraction as possible, and developing simple processes to facilitate implementation into processing plants without the need for complicated and expensive equipment. Three crab bio-products were obtained: pigmented vegetable oil, pigmented protein powder, and chitin. Carotenoid extractions were performed using vegetable oils (corn, canola, and sunflower oils), giving between 24.85% and 37.93% astaxanthin recovery. Citric acid was used to demineralize the remaining material and afforded a pigmented protein powder. Three different proteases were used to deproteinate and isolate chitin in yields between 17.06% and 19.15%. The chitin was still highly colored and therefore decolorization was attempted using hydrogen peroxide. Characterization studies were conducted on each of the crab bio-products isolated including powder X-ray diffraction analysis on the chitin (80.18% crystallinity index, CI, achieved using green methods). Overall, three valuable bio-products could be obtained but further research is needed to obtain pigment-free chitin in an environmentally friendly manner.

A first look at megabenthic community responses to seasonal change using the new Holyrood Subsea Observatory in Conception Bay, NL

Sub-Arctic seafloor communities rely on seasonal phytoplankton blooms for food, revealing a tight benthic-pelagic coupling. To maximize resource availability for offspring, organisms such as snow crabs, sea stars, and sea cucumbers synchronize their reproductive and feeding behaviours with spring blooms. Due to climate change, spring blooms are occurring earlier in sub-Arctic regions, leading to a possible mismatch between timing of resource availability and important life-history behaviours. Here, we utilize high-frequency time-series observations from the Holyrood Subsea Observatory, a new cabled seafloor observatory deployed in Conception Bay, Newfoundland. We use hourly data collected from environmental sensors (Conductivity-Temperature-Depth, Acoustic Doppler Current Profiler, fluorometer), a near-surface mooring (fluorometer), and a video camera to identify and quantify abundance and diversity of benthic megafauna, and to determine how community composition changed from pre-bloom to full bloom conditions. Data analysis revealed striking temporal changes in benthic activity, with the notable emergence of Psolus cf. phantapus sea cucumbers (up to 289.9 indiv./m2) coinciding with increased chlorophyll-a concentration and seawater temperature. At least three dense schools of forage fish, two Atlantic herring (79 and 144 indiv. frame−1) and one capelin (91 indiv. frame−1), were observed during the main bloom between May 5 and June 16. This study provides the first high-frequency in situ observations of benthic community response to seasonal food input in the region. The high temporal resolution made it possible to record the precise timing of the of Psolus cf. phantapus emergence in relation to the timing of food input to the seafloor, which will provide a baseline to monitor phenology as climate change progresses. Changes to the timing of spring blooms have implications for sub-Arctic fisheries productivity and ecosystem functioning, making continuous long-term monitoring of seafloor communities essential.

Spatially varying catchability for integrating research survey data with other data sources: case studies involving observer samples, industry-cooperative surveys, and predators as samplers

Spatio-temporal models are widely applied to standardise research survey data and are increasingly used to generate density maps and indices from other data sources. We developed a spatio-temporal modelling framework that integrates research survey data (treated as a “reference dataset”) and other data sources (“non-reference datasets”) while estimating spatially varying catchability for the non-reference datasets. We demonstrated it using two case studies. The first involved bottom trawl survey and observer data for spiny dogfish ( Squalus acanthias) on the Chatham Rise, New Zealand. The second involved cod predators as samplers of juvenile snow crab ( Chionoecetes opilio) abundance, integrated with industry-cooperative surveys and a bottom trawl research survey in the eastern Bering Sea. Our integrated models leveraged the strengths of individual data sources (the quality of the reference dataset and the quantity of non-reference data), while downweighting the influence of the non-reference datasets via the estimated spatially varying catchabilities. They allowed for the generation of annual density maps for a longer time-period and for the provision of one single index rather than multiple indices each covering a shorter time-period.

Eyestalk transcriptome and methyl farnesoate titers provide insight into the physiological changes in the male snow crab, Chionoecetes opilio, after its terminal molt

The snow crab, Chionoecetes opilio, is a giant deep-sea brachyuran. While several decapod crustaceans generally continue to molt and grow throughout their lifetime, the snow crab has a fixed number of molts. Adolescent males continue to molt proportionately to their previous size until the terminal molt at which time an allometric increase in chela size occurs and an alteration of behavioral activities occurs, ensuring breeding success. In this study, we investigated the circulating concentrations of methyl farnesoate (an innate juvenile hormone in decapods) (MF) before or after the terminal molt in males. We then conducted eyestalk RNAseq to obtain molecular insight into the regulation of physiological changes after the terminal molt. Our analyses revealed an increase in MF titers after the terminal molt. This MF surge may be caused by suppression of the genes that encode MF-degrading enzymes and mandibular organ-inhibiting hormone that negatively regulates MF biosynthesis. Moreover, our data suggests that behavioral changes after the terminal molt may be driven by the activation of biogenic amine-related pathways. These results are important not only for elucidating the physiological functions of MFs in decapod crustaceans, which are still largely unknown, but also for understanding the reproductive biology of the snow crab.

Transcriptional and metabolomic investigation of the stress response in snow crab during simulated transport condition (Chionoecetes opilio)

The molecular mechanisms underlying the stress response are poorly described in crustaceans. This includes the snow crab (Chionoecetes opilio), a commercially important stenotherm species distributed throughout the northern hemisphere. A better understanding of the stress response in C. opilio is desperately needed for commercial and conservation purposes. The purpose of this study was to investigate the transcriptional and metabolomic response of C. opilio exposed to stressors. Crabs were randomly assigned to 24 or 72 h treatment groups where they were exposed to conditions simulating live transport (handling and air exposure). A control group was kept in cold (2 °C) and well‑oxygenated saltwater. The hepatopancreas of the crabs was sampled to perform RNA-sequencing and high-performance chemical isotope labeling metabolomics. Differential gene expression analyses showed that classic crustaceans' stress markers, such as crustacean hyperglycemic hormones and heat shock proteins, were overexpressed in response to stressors. Tyrosine decarboxylase was also up-regulated in stressed crabs, suggesting an implication of the catecholamines tyramine and octopamine in the stress response. Deregulated metabolites revealed that low oxygen was an important trigger in the stress response as intermediate metabolites of the tricarboxylic acid cycle (TCA) accumulated. Lactate, which accumulated unevenly between crabs could potentially be used to predict mortality. This study provides new information on how stressors affect crustaceans and provides a basis for the development of stress markers in C. opilio.

Modelled dispersal of snow crab (Chionoecetes opilio) larvae and potential settlement areas in the western Barents Sea

Abstract Since the mid-1990s, a snow crab (Chionoecetes opilio) population has established in the eastern Barents Sea. Spawning females and newly hatched larvae are now also found in the central Barents Sea, warranting speculations on a further westward colonization by pelagic larvae. Here, we model the potential for larval dispersal and settlement into uncolonized areas in the western Barents Sea. We used a biophysical model of ocean currents and hydrography, coupled with a Lagrangian dispersal algorithm and larval survival functions as response to temperature. The model predicts limited dispersal from the central Barents Sea to western areas, primarily due to a mismatch between prevailing temperature regimes and temperature tolerances for the different larval stages. In addition, there was limited westward transport of water masses with temperatures that would allow completion of the pelagic larval development. We speculate that for larvae to successfully supply benthic recruits to the remaining uncolonized areas in the western Barents Sea, adult crabs would first need to establish new spawning aggregations, for example along the western slopes of the Barents Sea shelf. Immediate implications are limited potential for expanding the fishery to the western areas of the Barents Sea.

Grooved tanner crab &lt;i&gt;Chionoecetes tanneri&lt;/i&gt; in the north-western Bering Sea: criteria for choosing the optimal fishing measure

Spatial and bathymetric distribution and aggregation density is considered for bathyal crabs, including the grooved tanner crab &lt;i&gt;Chionoecetes tanneri&lt;/i&gt;, on the data of specialized deep-water trap survey and two bottom trawl surveys within the depth range of 300‒1080 m conducted by TINRO in the northwestern Bering Sea in 2019–2020. The size of grooved tanner crab is determined as 9.0–17.0 cm for the morphometrically mature males and 6.5–15.5 cm for the morphometrically immature males, by carapace width. The size of 50 % morphometric maturity is evaluated for males of &lt;i&gt;Ch. Tanneri&lt;/i&gt; in the northwestern Bering Sea. A new fishing measure is substantiated for this population taking into account its size composition.

The raw material base of water biological resources in the russian waters of the Chukchi sea and its cost

The studies carried out in this work made it possible to characterize the dynamics of the raw material base of aquatic biological resources of the Russian waters of the Chukchi Sea in 1997–2020 and evaluate its value at the present stage. The raw material base of marine fish and invertebrates varied from 5,4 to 450,1 thousand tons (with an average value of 196,7 thousand tons). It was based on marine fish – an average of 189,0 thousand tons (96,1% of all resources), stocks of invertebrates – 7,7 thousand tons (3,9%). Estimates of the commercial WBR biomass in the Chukchi Sea are approximately 24 times lower than the estimates of the resource base of the western part of the Bering Sea: 4,1 and 5,1% of the biomass of marine fish and invertebrates, respectively. Stocks of hydrobionts showed a gradual downward trend from 1997 to 2007, a low level in 2008–2017 and a sharp rise in 2018–2020. Significant growth in resources in the late 2010s led to mass walleye pollock migration to the Chukchi shelf from the Bering Sea, which led to an increase in the raw material base of WBR by 431 thousand tons and a concomitant increase in its cost by 23,7 billion rubles. The cost of the raw material base of the Russian waters of the Chukchi Sea in 2019–2020 amounted to 34–51 billion rubles, in absolute terms yielding to the Bering and Okhotsk seas by 14,0 and 31,3 times. The most valuable species of bioresources in terms of value were cod fish (walleye pollock Gadus chalcogrammus) and crabs (snow crab Chionoecetes opilio), the total contribution of which exceeds 90% of the total value of the estimated commercial stocks of the sea. With a high probability, it can be assumed that it is these types of WBR that will form the economic basis of the Russian fishery in the Chukchi Sea in the future.

Correction to: Infaunal and epifaunal secondary production in the Barents Sea, with focus on snow crab (Chionoecetes opilio) prey resources and consumption

Correction to: Infaunal and epifaunal secondary production in the Barents Sea, with focus on snow crab (<i>Chionoecetes opilio</i>) prey resources and consumption

Genome sequence of Chionoecetes opilio bacilliform virus, a nimavirus infecting the snow crab Chionoecetes opilio.

Nimaviridae (class Naldaviricetes) is a family of double-stranded DNA viruses infecting crustaceans, with the only officially recognized representative being white spot syndrome virus (WSSV). Chionoecetes opilio bacilliform virus (CoBV) was isolated as the causative agent of milky hemolymph disease in the snow crab Chionoecetes opilio, an economically important crustacean in the northwestern Pacific. Here, we present the complete genome sequence of CoBV and show that it is unambiguously a nimavirus. The CoBV genome is a 240-kb circular DNA molecule with 40% GC content that encodes 105 proteins, including 76 WSSV orthologs. Phylogenetic analysis based on eight naldaviral core genes established that CoBV is a member of the family Nimaviridae. The availability of the CoBV genome sequence provides a deeper understanding of CoBV pathogenicity and nimavirus evolution.

Biological Characteristics of the Great Sculpin Myoxocephalus polyacanthocephalus (Cottidae) from Pacific Waters off the Kuril Islands and Southeastern Kamchatka in Autumn Period

The spatial distribution, size-sex composition, feeding of Myoxocephalus polyacanthocephalus and accompanying species in the Pacific waters off the northern Kuril Islands and southeastern Kamchatka in the autumn period are considered. In August–November 1997, this species was represented in catches by individuals with a length of 30-89 (on average 47.8 ± 0.5) cm and a body weight of 300–11000 (2321 ± 90) g. Females dominated over males; the sex ratio was 1.2 : 1.0. The relationship between the body weight and length of great sculpin is described by the exponential equation: W = 0.0031FL3.446 (R2 = 0.935). The food spectrum of great sculpin includes fish (56.2% of the diet), mainly the walleye pollock Gadus chalcogrammus and Atka mackerel Pleurogrammus monopterygius (19.9 and 11.9%, respectively); fish processing wastes (19.6%), mainly heads of Atka mackerel (12.2%); as well as decapods (18.6%), mainly the snow crab Chionoecetes opilio (14.1%). As great sculpin grow, decapods are replaced by fish in the diet and walleye pollock is replaced by Atka mackerel and Liparidae. The size and sex composition and feeding patterns of great sculpin as well as the species composition of the accompanying species differed in some parts of the surveyed area. The co-occurrence of great sculpin with walleye pollock and the northern rock sole Lepidopsetta polyxystra was 100%.

A quantitative analysis of greenhouse gases emissions from catching swimming crab and snow crab through cross-analysis of multiple fisheries

A quantitative analysis of greenhouse gases emissions from catching swimming crab and snow crab through cross-analysis of multiple fisheries

Unintended consequences of climate‐adaptive fisheries management targets

AbstractClimate change is projected to affect the productivity of global fisheries. Management based on maximum sustainable yield (MSY) has been effective at eliminating overfishing in many regions. However, continuing to use yield‐maximizing targets under climate‐driven changes in productivity can result in higher anthropogenic pressure on populations subject to climate‐related stress than maintaining status quo management targets. We demonstrate this effect using a theoretical example and case studies from snow crab in the eastern Bering Sea and a global marine fisheries database. In these examples, the conservation gain (i.e. biomass in the ocean) of maintaining status quo management targets is larger than the small gain in harvest made through climate adaptation in MSY‐based management. The aggregate conservation gain of maintaining management targets increases as the harmful impacts of climate change on productivity worsen. Instead of climate‐adaptive MSY‐based targets, new management tools are needed to balance conservation and food production in ecosystems of populations displaying non‐stationary productivity.

The complete mitochondrial genome of the hybrid snow crab Chionoecetes opilio (♀) × C. japonicus (♂) (Crustacea: Decapoda: Majoidea) and its phylogenetic analysis

We report the complete mitochondrial genome of a hybrid snow crab between a femaleChionoecetes opilioand maleC.japonicus. The circular genome was 16,065 bp in length, and consisted of 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes, and a control region. The composition and arrangement of its complete mitochondrial genome were very similar to that reported for the maternal species,C.opilio. The close genetic relationship is reflected in the phylogenetic tree and supports maternal inheritance patterns.

Increasing sustainability in food production by using alternative bait in snow crab (Chionoecetes opilio) fishery in the barents sea

The use of food grade wild-captured species as bait for other fisheries questions the sustainability of food production. In pot fisheries, bait is an important factor determining the effectiveness of the gear. In snow crab (Chionoecetes opilio) fishery, the pots are normally baited with squid (Illex sp.) and herring (Clupea harengus). This fishery uses substantial amounts of bait for each pot deployment, and it constitutes one of the largest expenses for operating the pots along with costs for fuel. Furthermore, reliance on bait that originates from wild-capture fisheries questions economic and environmental sustainability, and involves additional use of fuel for capture and transportation of the bait which increases the carbon footprint of the industry. Therefore, the use of alternative bait sources is needed. One such alternative bait source can be originating from processed by-products from commercial fisheries. However, for the new bait to be acceptable for the fishery, it must provide comparable catch efficiency as the traditional bait. Therefore, this study aimed at comparing the performance of a new experimental bait against the traditionally used squid bait in the Barents Sea snow crab fishery. The results showed no statistically significant difference in catch efficiency of target-sized snow crab. Specifically, a formal uncertainty estimation based on nested bootstrapping showed that there was no significant difference in efficiency between bait types for target-sized individuals for soak times typically employed in the fishery. Thereby this shows a potential to increase sustainability in food production and a positive effect on the size selectivity by additionally demonstrating a reduced capture of undersized individuals.