Snow Crab Fishery Research Articles

Rethinking user rights of profitable marine invasions: Lessons from the Norwegian Barents Snow Crab fishery

Profitable marine invasions can occur when a newly arrived invasive species not only negatively changes ecosystem characteristics but is also exploited as a valuable market commodity. Such species pit existing ecosystem production values against potential value paths as their presence instigates management decisions that may vary from favoring a conservative, status quo approach on one end to a more risk-loving, adaptive approach on the other. Despite commitments to environmental treaties for limiting spread, local interests may purposefully support growth of invasions for their benefit. Potential value paths will depend not only on the ecological changes in the natural capital supporting the profitable resource extraction but also the user rights developed to address the changing asset structure and productivity. Current economic thinking suggests that the stronger the user rights in addressing questions of exclusivity, security and duration, the higher the gains to the present value of expected benefits from the rights. We discuss how both scale and uncertainties regarding irreversible ecological value and productivity shifts may require refinement of this theory. We explore the Barents Sea Snow Crab (Chionoecetes opilio) fishery, with particular attention to the Norwegian approach to its management. The uncertain ecological impacts of this invasive species have led to international disputes and significant management challenges. Norway has implemented exclusionary policies by designating the crab as sedentary to limit foreign access, sparking conflicts over the Svalbard Treaty. These unilateral actions have led to fines, court cases, and diplomatic tensions. As the Snow Crab expands toward sensitive Arctic habitats, a broader governance approach is needed. We take a critical look at the exclusivity, security, and durability of property rights associated with the Norwegian Snow Crab fishery, assessing their inherent weaknesses and implications since the onset of the fishery in 2012. As there is a growing interest in developing profitable resource exploitation and fisheries for new, often invading species, the Norwegian Snow Crab fishery provides valuable lessons and guidance for governance and management of such resources, aiming to mitigate risks and foster economically viable and environmentally responsible practices.

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

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

Development of a stock-specific management procedure for snow crab fishery in the Sea of Japan using conditioned surplus production models in a data-moderate situation

A management procedure (MP) automatically calculates an acceptable biological catch from input data, and its performance is quantitatively evaluated by closed-loop simulations of population dynamics with their uncertainties (operating models). In snow crab in the Sea of Japan, an MP based on survey biomass estimates was adopted by stakeholders, rather than a generic MP recommended for data-moderate Japanese stocks. This was done without quantifying its performance owing to data and resource limitations. This study evaluated the performance of the existing MPs and modified the generic MP through closed-loop simulations with state-space surplus production models (SSPMs) conditioned with actual data. The survey-based MP generally worked well to achieve sustainable catch and biomass but tended to be sensitive to the bias in biomass estimates. The modified MP can be more robust to the bias than the survey-based MP with higher catches than the generic MP. This study demonstrates that, although continuing efforts of collecting composition data are inevitable, SSPM could be used as the conditioned operating models even in data-limited situations to sufficiently represent the stock status and its uncertainty.

A regional analysis of climate change effects on global snow crab fishery

AbstractThe snow crab fishery faces increasing vulnerability to environmental factors, yet the literature on the relationship between climate change and snow crab harvest remains limited. This study estimates snow crab harvest functions using climate change indicators with unbalanced panel data of snow crab production from the eastern Bering Sea (Alaska), the southern Gulf of St. Lawrence (Canada), the Sea of Japan, and the Barents Sea (Norway‐Russia). The relationship between snow crab biomass, stock, and catch is analyzed and the endogeneity of stock in the harvest function is also addressed using climate change indicators as instrumental variables (IVs). The results show that the extent of Arctic sea ice is effective in addressing the endogeneity, and the random effects IV model with error components two stage least squares estimator performs the best to control heterogeneity. A 1% increase in snow crab fishing effort is associated with a 0.42% increase in snow crab harvest, and a 1% increase in snow crab stock causes a 0.98% increase in snow crab harvest. The reported estimates indicate a large stock‐harvest elasticity and provide supporting evidence to prioritize stock enhancement in snow crab fishery policy designs to maintain stocks at sustainable levels and minimize government expenditures on subsidies.Recommendations This study explores how snow crab harvests are influenced by snow crab populations and fishing efforts in the context of global warming across various global regions, including the Bering Sea, the Gulf of St. Lawrence, the Sea of Japan, and the Barents Sea. A 1% increase in fishing effort is associated with a 0.42% increase in harvest, while a 1% increase in snow crab population leads to a 0.98% increase in harvest, showing a high dependency on snow crab biomass. Arctic sea ice extent is identified as a crucial climate factor affecting snow crab biomass and harvests, making it a valuable variable for understanding and managing snow crab populations. The study supports the prioritization of stock enhancement policies by fishery agencies and suggests standardizing how fishing effort is measured across different regions to improve snow crab fishery management and future research.

Trends of ocean temperature influencing snow crab catch along the Scotian Shelf

The snow crab (Chionoecetes opilio) fishery has great economic importance for Nova Scotia, contributing $263 million to fisheries and more than one-fifth of Canadian snow crab revenues in 2021. Being a stenothermic species, snow crabs can only live within a narrow range of temperatures between −1 to 6 °C. The Scotian Shelf holds the southernmost populations of snow crab in the Atlantic and snow crab catch-per-unit-area (CPUA) in the Scotian Shelf. Trawl survey data from Ocean, because these cold-temperature requirements are a limiting factor for its distribution. This study investigates the relationship between bottom ocean temperature Fisheries and Oceans Canada from 2012 to 2021 were used. Through nonlinear modelling, CPUA (mt/km2) was regressed with respect to bottom ocean temperature along Northwest Atlantic Fisheries Organization divisions N-ENS, CFA 23, CFA 24, and CFA. The temperature-vs-CPUA relationship was unimodal for all studied years. The best-fit models explained a limited amount of variation, but CPUA consistently decreased to zero towards the highest recorded temperatures. Due to the ongoing global warming, bottom ocean temperatures across the Scotian Shelf will likely continue to increase, which thus might harm the Scotian Shelf snow crab fishery. In conclusion, this study underscores the potential impact of global warming on the economically significant snow crab fishery in the Scotian Shelf. The findings serve as a critical alert to the possible consequences of rising ocean temperatures, thereby contributing to our understanding and preparation for the future of marine ecosystems and industries.

Walking sideways? Management of the Norwegian snow crab fishery

The snow crab (Chionoecetes opilio) in the Barents Sea is an invasive species, first discovered in 1997. Since 2012, a commercial fishery has developed, and various management measures have been implemented. Despite fishing gear restrictions, limits for the catch season and the implementation of a TAC-regime in 2017 onwards, the fishery struggles with substantial sustainability challenges. Vessels allocated a licence demonstrate radical differences in catches, and the fleet suffers from an unprofitable overcapacity and lack of environmentally friendly harvesting operations. The management authorities and the fishermen's organizations seem to agree that the regulated open access and the Olympic fisheries model are the main sources of the present problems. The Directorate of Fisheries (DoF) [1] has introduced a discussion paper outlining various options for closing the fishery. The article outlines these- and other options, and discusses the alternatives in terms of improved sustainability, i.e., environmental, economic as well as social. A key point is that closing the fishery (like many other management measures), are not only technical interventions. They are also political, and they contribute to modify both the regulating system and the system to be regulated.

Diversity of fishing strategies and high spatial adaptivity in the Alaskan snow crab fishery

Diversity of fishing strategies and high spatial adaptivity in the Alaskan snow crab fishery

Selectivity in snow crab (Chionoecetes opilio) pot fishery: Effect of escape gap shape and size for conservation of fishery resources

Conical pots are commonly used fishing gear for capturing snow crab (Chionoecetes opilio). In these fisheries, optimal snow crab size selection is important for reducing unintended mortality of undersized individuals aiming at conserving fisheries resources and reducing sorting time onboard fishing vessels. Size selection in snow crab pot fisheries commonly takes place through pot netting meshes during deployment. The diamond mesh netting has varying opening angles affecting retention of snow crab of different sizes, and often large proportions of catches consist of undersized crab challenging natural resource conservation. Some commercial snow crab fisheries use rigid escape gaps in addition to mesh selection to improve size selectivity. In this study, we predict the size selection potential of escape gaps with different shape and size and investigated whether such additional size selection mechanism can have a potential to improve selectivity compared to mesh selection. Results showed that circular escape gaps have potential to provide sharper size selection compared to netting meshes and thus could be used to limit the capture of undersized snow crab which is relevant for management and conservation of snow crab resources. However, a similar positive effect cannot be obtained to the same extent with elliptical and rectangular escape gaps.

Does soak time influence the effect of artificial light on catch efficiency in snow crab (Chionoecetes opilio) pot fishery?

In the Barents Sea commercial snow crab (Chionoecetes opilio) fishery, an increase in catch efficiency of the conical pots is important for the profitability of the industry. Light emitting diodes (LEDs) have previously been tested for increasing catch efficiency of the snow crab pots. These earlier experiments have shown varying results ranging from large increase in snow crab catches to no significant effect. These experiments have used different pot soaking times; however, the soaking time might affect the impact of LEDs on catch efficiency. In commercial snow crab fishery, the pot soak time is varying which has not been considered in earlier experiments testing the effect of LEDs. Therefore, this study examined whether pot soaking time can explain the observed differences in relative catch efficiency of snow crab pots with and without LEDs with soak times ranging from 2 to 14 days in the Barents Sea snow crab fishery. For target sizes of snow crab (≥95 mm carapace width), results indicated an increase in catch efficiency between 10 and 30% for pots with LEDs with exception of one experiment using six days soak time. However, experimental results were subjected to large uncertainties and, except from one experiment with five days soak time, the estimated increases were nonsignificant. Furthermore, the pot soak time was not found to impact the effect of white LEDs on capture efficiency.

Chocolate squid (Todarodes pacificus) bait reduces snow crab catch rates

This study evaluated the performance of chocolate squid (Todarodes pacificus) bait as a lower-cost alternative to traditional squid bait in a snow crab (Chionoecetes opilio) fishery in Eastern Canada. The results showed that pots with chocolate squid bait had significantly lower catch rates compared to pots with traditional squid bait. The chocolate squid bait significantly reduced the number of crabs caught per pot by 13.99% and the weight of crabs caught per pot by 2.88 kg. Although the chocolate squid bait is cheaper, the decrease in catch rates could require increased effort to reach individual quotas, which could lead to longer or more frequent fishing trips and more traps being fished, increasing fuel consumption and habitat disruption, resulting in negative environmental impacts. Finding alternative lower-cost baits that maintain catch rates remains a key priority for reducing operational costs and minimizing environmental impacts in the snow crab 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 < 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 < 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.

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.

Increasing Sustainability in Food Production by Using Alternative Bait in Snow Crab (Chionoecetes Opilio) Fishery in the Barents Sea

Increasing Sustainability in Food Production by Using Alternative Bait in Snow Crab (Chionoecetes Opilio) Fishery in the Barents Sea

Environmental constraints, biological growth and fleet dynamics of a developing fishery: A model study of the Barents Sea snow crab (Chionoecetes opilio, Majidae) fishery

AbstractThe snow crab (Chionoecetes opilio, Majidae) has recently entered the Barents Sea, and a crab fishery is developing. Information on how the crab appeared and where it is moving is limited. We study how the characteristics of the fleet may affect the further development of the fishery. A spatial model is constructed as a grid of cells given a carrying capacity for crab determined by environmental data, assumed to reflect crabs' preferences. The biological dynamics are modelled using cellular automata, describing the growth and movements of the crabs. The fleet dynamics is represented by scenarios of fleet behaviour and aptitude, using standard theories of harvest production and economics. Pattern‐oriented modelling is used to calibrate the model. The fishery started in the Loophole, but is anticipated to expand as the crabs populate adjacent areas. We use simulations to explore a potential geographical expansion of the fishery. The fleet is assumed to continually expand the current fishing area by initiating fishing in adjacent areas, relying only on their own judgement to locate promising fishing grounds. We find an inability to successfully quantify the amount of crabs in the areas subject to exploration and the willingness to take risks to be two forces contributing to a long‐term utilization of the stock. Both forces appear to make the fishers explore non‐lucrative grounds, potentially leading them to lucrative grounds. However, information from other sources indicating the presence of crabs at various locations appears to be necessary to ensure a more complete exploration of the fishery.

Spatial and Temporal Variation in Annual versus Biennial Reproductive Cycles in Eastern Bering Sea Snow Crab Chionoecetes opilio

AbstractThe stock assessment model currently used for the management of the fishery for snow crab Chionoecetes opilio in the eastern Bering Sea assumes an annual reproductive cycle. However, temperatures below 1°C can extend the snow crab reproductive cycle to 2 years, which could depress the total reproductive potential of the stock. Our objective was to determine the prevalence of snow crab in the eastern Bering Sea on a biennial reproductive cycle, relative to latitudinal and thermal gradients, and evaluate whether available bottom temperature data could be used to predict the proportions of biennial spawners. Mature female snow crab were collected on the annual National Marine Fisheries Service eastern Bering Sea bottom trawl survey during 2014–2018. Bimodality in the frequency distribution of oocyte area suggests that oocyte area can likely be used to distinguish annual and year‐1 biennial spawners from year‐2 spawners. In 2014, the highest rates of biennial reproduction were found in northern, colder areas in the eastern Bering Sea. In 2015–2018, very low rates of biennial reproduction coincided with warm temperatures across the eastern Bering Sea. This work could help in the estimation of female reproductive potential and allow the development of female‐based reference points for the eastern Bering Sea snow crab fishery.

The effect of white and green LED-lights on the catch efficiency of the Barents Sea snow crab (Chionoecetes opilio) pot fishery.

In commercial snow crab (Chionoecetes opilio) fishery, the catch efficiency of the conical pots is important for increasing the profitability of the industry. This study evaluated the effect of adding green and white light emitting diodes (LED) on the catch efficiency of commercially used conical pots. The results from the field experiments showed that inserting artificial lights significantly increases the catch efficiency for snow crab over the minimum landing size of 95 mm carapace width of up to 76% when using green LED, and by 52–53% on average when using white LED. This study shows that it is possible to improve the catch efficiency of the snow crab fishery by applying artificial LED lights to the conical snow crab pots, potentially resulting in an important economic benefit to the snow crab fishery.

Effects of time-area closures on the distribution of snow crab fishing effort with respect to entanglement threat to North Atlantic right whales

AbstractTime-area closures are increasingly used to mitigate cetacean entanglement by temporarily excluding fishing effort from areas where high densities of cetaceans and fishing overlap. The effort displaced by these closures can be redistributed to the areas that remain open, changing the distribution and density of fishing effort outside the closures. These patterns were evaluated for the southern Gulf of St. Lawrence snow crab fishery by comparing recent years (2015–2017) with 2018 when time-area closures were implemented to protect North Atlantic right whales. A predictive model framework was created to test how well we could predict the response of fishers to closures. Approximately 29% of the total fishing effort was displaced by the 2018 closures, increasing effort density outside the closures by 41%. Displaced fishing effort shifted farther from the closures than predicted, into areas which, prior to 2018, had low effort density, producing a higher threat of entanglement in these new areas. Fishing effort in 2018 remained as high as 2017, despite a lower quota and reduced trap limit. Consequently, the resulting effects of time-area closures on fishing patterns outside of the closures cannot be discounted if entanglement threat to whales is to be successfully mitigated.

Hard to Manage? Dynamics of Soft-Shell Crab in the Newfoundland and Labrador Snow Crab Fishery

Capture of recently molted soft-shell crab in the Newfoundland and Labrador (NL) snow crab (Chionoecetes opilio) fishery is undesirable due to resource wastage associated with low meat yield and supposed high mortality rates upon discard. This study is intended to formalize best-practice management advice for avoidance of soft-shell crab in the fishery. The study investigates factors affecting soft-shell incidence in the catch across a large geographic stock range encompassing dynamic habitat and contrasting harvest rate strategies. The results demonstrate an interaction between seasonality and harvest rate in governing soft-shell crab levels in the fishery. Greatest potential for high soft-shell incidence occurs in late-spring or summer (June–July) fisheries in warm water populations subjected to heavy fishing pressure, with warm water populations shown to be associated with earlier molting periods. The study concludes that the optimal time to harvest snow crab is during winter or early spring, and advises that wherever winter or early spring fisheries are not possible, a best-practice management strategy is to minimize wastage by maintaining a strong residual biomass of large hard-shell males in the population at all times. This strategy is easily enabled by consistent application of low exploitation rates.

First observation of seasonal variations in the meat and co-products of the snow crab (Chionoecetes opilio) in the Barents Sea

The snow crab (Chionoecetes opilio), SC, is a newly established species in the Barents Sea. The snow crab fishery has established itself as a new and profitable industry in Norway in the last decade. The fishery started as a year-round fishery, without any information of possible seasonal variations in the quality of the product. In 2017 a total allowable catch was established by the Norwegian government, and the fisheries were subsequently closed during the summer months. In order to optimize fishing times, and to evaluate this growing industry in the Barents Sea, seasonal variations of the meat content of the clusters, as well as variations in content and quality of co-products were investigated, aiming to identify the seasons where the exploitation of different products from SC can be most profitable. The results show seasonal variations in meat content and in composition of co-products. The highest co-product quantities and meat content are from February to April, followed by a period from June to September with decreasing meat and co-products. Our recommendation is to capture the SC in the winter–spring period in the Barents Sea, supporting the current situation and creating most value for the fisheries.