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The Newfoundland and Labrador (NL) snow crab resource, presently the basis of the most important commercial fishery in the region, is in decline. Short-, mid-, and long-term recruitment prospects are deemed poor in most areas. Fishery declines have been most apparent in the north, beginning in the mid- to late 2000s, but are expected to begin in the more productive southern areas in the near future. A multitude of emergent theories to explain the resource decline have been hypothesized as contributing factors, including fishing, trawling impacts, seismic activities, disease, predation, and increasing temperature. This study comprehensively reviews and qualitatively relates the results of recent research and literature on each of these factors. We find that several factors may be contributing to a lack of recruitment in the stock, but diminishing produc- tivity resulting from a warming oceanographic regime is the primary cause of the resource decline. Further, we postulate that trends occurring in the snow crab stock are indicative of a broader-scale ecological regime shift occurring along the NL shelf.

Epibenthic communities play a key role in ecosystem functioning in Arctic shelf Seas, such as in the Chukchi Sea in the Pacific Arctic. These communities, however, are patchily distributed and are influenced by various environmental parameters. Along with taxonomic composition, another community aspect that may vary spatially and be influenced by the environment is the distribution of organism sizes. This study presents the first size frequency distributions of nine epifaunal taxa that were determined to be dominant in the eastern Chukchi Sea in July/August 2009 and 2010, including male, female and gravid Chionoecetes opilio and Hyas coarctatus crabs , the gastropods Neptunea spp., Plicifusus spp. , Colus spp., and Cryptonatica spp., and the echinoderms Gorgonocephalus spp. , Leptasterias spp., and Echinarachnius parma. Some abundant taxa exhibited a wide range of sizes (i.e. C. opilio , Neptunea spp., and Leptasterias spp.), while others had a much smaller size range (i.e. Cryptonatica spp. and E. parma ). We also found that size distributions of these taxa correlated with various combinations of the environmental parameters that have been shown to be important in structuring the general distribution patterns for the epibenthic invertebrate communities in the study area, including percent total sediment organic carbon, sediment chlorophyll a , temperature, latitude, sediment grain size 2 and 4 phi, pH, and dissolved oxygen. Our findings present benchmark information that is needed to detect future alterations in body-size frequency distributions that are likely to happen in response to the predicted climate and environmental changes in the Chukchi Sea region.

To understand more fully the larval dispersal and settlement of the snow crab Chionoecetes opilio in natural habitats, we tested the effects of temperatures ranging from ∼1–20°C and ∼1–18°C on the survival and developmental period of snow crab larvae in the zoeal and megalopal stages, respectively, through laboratory experiments. The survival rates of second zoeae and megalopae were significantly greater at 5–16°C and 5–14°C, respectively. There were no statistically significant differences among the survival rates of megalopae reared at 3–16°C, although greater survival rates were observed at 5–14°C. The mean numbers of days from hatching to second zoeae and megalopae and from megalopae to reach first crab instar were significantly shorter at warmer temperatures. Moreover, the relationships between mean temperatures and larval periods were well described by the heat summation theory equations. The threshold temperatures for larval development were estimated to be -2.24–0.63°C; they decreased wit...

The snow crab Chionoecetes opilio is an important fishery species in Japan. Hydrodynamics are vital to the distribution, recruitment and settlement of crab larvae in nursery areas. In this study, we developed a survival and transport model of snow crab larvae to investigate the interannual variability in larval settlement in three fishing areas: west of Toyama (region A), west of Niigata (region B) and west of Hokkaido (region C). We found that the female crab stock abundance determined the modeled number of zoea in regions A and B, whereas water temperature played a major role in the initial number of zoea in region C. As for larval settlement, the ocean current impacted settlement in region B, and water temperature was vital to settlement in region C. Both female crab abundance and hydrodynamics contributed to variability in settlement in region A. The results revealed contrasting recruitment patterns in the three fishing areas. Self-recruitment was the primary form in regions A and C, whereas both self-recruitment and recruitment from upstream sources were important in region B.

Data obtained using three different types of sampling gear is compared and combined to assess the size composition and density of a non-indigenous snow crab populationChionoecetes opilioin the previously free of alien species Kara Sea benthos. The Sigsbee trawl has small mesh and catches even recently settled crabs. The large bottom trawl is able to catch large crabs, but does not retain younger crabs, due to its large mesh. Video sampling allows the observation of larger crabs, although some smaller crabs can also be spotted. The combined use of such gear could provide full scope data of the existing size groups in a population. The density of the crabs was calculated from the video footage. The highest figures were in Blagopoluchiya Bay at 0.87 crabs/m2, where the settlement seems to be reaching its first peak of population growth after the introduction. High density in the Kara Gates Strait at 0.55 crabs/m2, could be due to the close proximity of the Barents Sea from where the crabs can enter by both larval dispersal and active adult migration. All size groups have been present in most sampled areas, which suggest successful settlement and growth of crabs over a number of years. Again, this was not the case in Blagopoluchiya Bay with high density of small crabs (

Decreasing sea ice in the Arctic is expected to impact marine ecosystems, and to lead to increased human activity in the form of shipping traffic, fishing pressure, and mineral resource exploration and extraction. In the face of these pressures, we examine genetic population structure in the snow crab Chionoecetes opilio (Fabricius, 1788), throughout its distribution in Alaskan waters, to determine degrees of population connectivity between the Arctic and more southerly portions of the species’ range. Snow crabs are widely distributed on the high-latitude continental shelves of North America, where they support a valuable commercial fishery in the United States and Canada. Fishing pressure in United States waters is currently concentrated in the Bering Sea, but large populations of snow crab also occur farther north in the Chukchi and Beaufort Seas. These northern stocks are not well studied, and not yet targeted by fisheries, although commercial-sized individuals were recently reported in areas of the Western Beaufort Sea. We used seven polymorphic microsatellite markers to examine tissue samples from 573 individual crabs collected at 12 sampling locations distributed across the Bering, Chukchi, and Beaufort Seas. These data indicate that Alaskan snow crabs constitute one large, panmictic population. Connectivity between fishery areas in the south and unexploited regions farther north thus appears to be substantial, perhaps due to a lengthy larval dispersal period and highly mobile adult population.

*Мл. н. с., Магаданский научно-исследовательский институт рыбного хозяйства и океанографии 685000 Магадан, Портовая, 36/10 Тел., факс: (4132) 607-419 E-mail: lpb@magniro.ru Ст. н. с., Камчатский научно-исследовательский институт рыбного хозяйства и океанографии 683000 Петропавловск-Камчатский, Набережная, 18 Тел., факс: (4152) 412-701 E-mail: ryazanova.t.v@kamniro.ruОХОТСКОЕ МОРЕ, КРАБ-СТРИГУН ОПИЛИО, TRICHOMARIS INVADENS, ПРЕВАЛЕНТНОСТЬ, «АСФАЛЬТОВАЯ» БОЛЕЗНЬ

RATIONALE We report the matrix-assisted laser desorption/ionization mass spectrometric (MALDI-MS) characterization of the cryptocyanin proteins of the juvenile Chionoecetes opilio crabs during their molting and non-molting phases. In order to assess the structural cryptocyanin protein differences between the molting and non-molting phases, the obtained peptides were sequenced by MALDI low-energy collision-induced dissociation tandem mass spectrometry (CID-MS/MS). METHODS The cryptocyanin protein was isolated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and analyzed by MALDI-TOF/TOF-MS. The purified cryptocyanin protein was sequenced, using the 'bottom-up' approach. After tryptic digestion, the peptide mixture was analyzed by MALDI-QqTOF-MS/MS and the data obtained were used for the peptide mass fingerprinting (PMF) identification by means of the Mascot database. RESULTS It was demonstrated using MALDI-TOF/TOF-MS that the actual molecular weights of the non-molting and molting cryptocyanin proteins were different; these were, respectively, 67.6 kDa and 68.1 kDa. Using low-energy CID-MS/MS we have sequenced the trytic peptides to monitor the differences and similarities between the cryptocyanin molecular structures during the molting and non-molting stages. CONCLUSIONS We have demonstrated for the first time that the actual molecular masses of the cryptocyanin protein during the molting and non-molting phases were different. The MALDI-CID-MS/MS analyses allowed the sequencing of the cryptocyanins after tryptic digestion, during the molting and non-molting stages, and showed some similarities and staggering differences between the identified cryptocyanin peptides. Copyright © 2013 John Wiley & Sons, Ltd.

Fishing experiments were carried out in the adjacent sea of Yeongil Bay, the eastern cost of Korea from 2003 to 2004 using the dome-shaped pots with different five mesh sizes (17.1, 24.8, 35.3, 39.8, and 48.3mm) in order to determine the size selectivity of pots for the whelk, Buccinum opisthoplectum. The catch species were composed of Buccinum opisthoplectum (45.4%), Buccinum striatissimum (30.1%), Pandalopsis japonica (9.3%), Chionoecetes opilio (8.9%), and so on. The shell height (l) of Buccinum opisthoplectum caught in the experimental fishing pots was measured. The SELECT (Share Each Length`s Catch Total) analysis method was applied with fishing data to obtain master selection curve. The model with the estimated split parameter was found to fit the catch data best. The master selection curve was estimated to be s (R)〓exp (7.833R-10.871)/[1 + exp (7.833R-10.871], where R is the ratio of shell height to mesh size. The relative shell length for 50% retention was 1.388, and the selection range was 0.281. It means that the pots of larger mesh size allow more whelks of small size to escape.

Major habitats for the snow crab Chionoecetes opilio are mostly found within the northwest Atlantic and North Pacific Oceans. However, the East Sea populations of C. opilio, along with its relative the red snow crab (C. japonicas), are two of the most important commercial crustacean species for fisheries on the east coast of the Korean Peninsula. The East Sea populations of C. opilio are facing declining resources due to overfishing and global climate change. Thus, an analysis of population structure is necessary for future management. Five Korean and one Russian group of C. opilio were analyzed using nine microsatellite markers that were recently developed using next-generation sequencing. No linkage disequilibrium was found between any pair of loci, indicating that the markers were independent. The number of alleles per locus varied from 4 to 18 with a mean of 12, and allelic richness per locus ranged from 4.0 to 17.1 across all populations with a mean of 9.7. The Hardy–Weinberg equilibrium test revealed significant deviation in three out of nine loci in some populations after sequential Bonferroni correction and all of them had higher expected heterozygosity than observed heterozygosity. Null alleles were presumed in four loci, which explained the homozygosity in three loci. The pairwise fixation index (F ST ) values among the five Korean snow crab populations did not differ significantly, but all of the pairwise F ST values between each of the Korean snow crab populations and the Russian snow crab population differed significantly. An UPGMA dendrogram revealed clear separation of the Russian snow crab population from the Korean snow crab populations. Assignment tests based on the allele distribution discriminated between Korean and Russian origins with 93 % accuracy. Therefore, the snow crab populations around the Korean Peninsula need to be managed separately from the populations in Bering Sea in global scale resource management. Also, this information can be used for identification of snow crab origin which is problematic in worldwide crab trade.

Sources for spatial variability of benthic megafaunal communities in the northeastern Chukchi Sea are poorly documented and may include altered water circulation patterns, as noted for macrofauna. Spatial variability of megafauna was investigated by sampling with a plumb-staff beam trawl in three petroleum leases, the Klondike, Burger, and Statoil study areas, as part of a multi-disciplinary research program in the northeastern Chukchi Sea ecosystem. Trawling occurred during two sampling periods from 2009 and one in 2010 with a total of 81 trawls from 38 stations. A total of 99 discrete taxonomic categories were identified in 2009 and 2010 which were expanded to 239 taxa in the laboratory. Biomass in the three study areas ranged from ∼15,500 to ∼96,000 g 1000 m −2 and numerical density ranged from ∼8500 to ∼134,000 individuals 1000 m −2 . Although the megabenthic species-assemblages in all three study areas were similar in composition, average biomass values were higher in Burger (ranging from ∼54,000 to ∼96,000 g 1000 m −2 ) where altered water circulation occurs, than in Klondike (ranging from ∼15,500 to ∼31,000 g 1000 m −2 ) or Statoil (∼15,000 g 1000 m −2 ). The brittle star Ophiura sarsi was the numerically dominant megafauna (70% of total biomass) followed by the snow crab Chionoecetes opilio (7% total biomass), as noted in prior investigations in the region. Biomass and density of benthic megafauna in this region reflected the high quantities of seasonal production reaching the benthos in the shallow waters of the Chukchi Sea. Differences in benthic communities among study areas were associated with variations in bottom-water temperature and latitude, and to a lesser extent, water depth and percent mud. We believe these associations arise from effects of topography on northward-flowing water, that create regions of slower currents, and consequently, higher organic deposition.

Bowhead whales (Balaena mysticetus) of the western Arctic stock winter in icecovered continental shelf regions of the Bering Sea, where pot fisheries for crabs (Paralithodes and Chionoecetes spp.) and Pacific cod (Gadus macrocephalus) pose a risk of entanglement. In the winter of 2008–2009 and 2009–2010 the spatial distribution of 21 satellite tagged bowhead whales partially overlapped areas in which pot fisheries for cod and blue king crab (Paralithodes platypus) occurred. However, these fisheries ended before whales entered the fishing areas, thus avoiding temporal overlap. A fishery for snow crab (Chionoecetes opilio) typically runs from January to May and provides the greatest potential for bowhead whales to encounter active pot gear. Tagged whales did not enter the area of the snow crab fishery during this study and generally remained in areas with >90% sea ice concentration, which is too concentrated for crab boats to penetrate. Pack ice sometimes overruns active fishing areas, resulting in lost gear, which is the most likely source of entanglement. The western Arctic stock of bowhead whales was increasing as of 2004; as such, incidental mortality from commercial pot fisheries is probably negligible at this time. Regardless, entanglement may increase over time and should be monitored.

Natural mortality rate is a key parameter in ecology and fisheries, but it may be difficult to estimate for methodological reasons and because it is highly variable and often confounded with other factors such as fishing mortality and migration. This is especially true for crustaceans in general, because age determination is problematic, and for snow crab (Chionoecetes opilio) in particular because density-dependent processes may lead to highly variable mortality rates across life history stages. In this context, we developed an original method to estimate the natural mortality rate of adult (i.e. terminally molted) female snow crab, and its consequences on egg production. This new method relies on shell condition, carapace width and abundance of adult females and was applied to a time series (1991–2012) of annual trawl survey data for a snow crab population in the Gulf of St. Lawrence, eastern Canada. Two natural mortality estimates were provided by the method depending on two distinct assumptions about the survey. Both estimates (0.66 and 0.78 year–1) were high compared to previous estimates for snow crab. These values imply that female life expectancy after terminal molt was short and that primiparous females (first-time spawners) contributed a large share (at least 81%) of the total number of eggs produced by the case-study population over the period 1992–2010.

The growth per molt of snow crab Chionoecetes opilio in the eastern Bering Sea is poorly known, primarily because snow crabs are difficult to sample during their spring molting period due to the presence of sea ice. To provide better estimates of growth per molt for the stock assessment model used to manage the snow crab fishery, a study was conducted to collect juvenile crabs with a bottom trawler and return them to holding facilities at Dutch Harbor and Kodiak, Alaska. Since relatively few of these crabs subsequently molted, these data were augmented with molting data collected by two previous, unpublished studies. Based on a total of 35 observations, snow crabs grew according to the following premolt (PRMW ) and postmolt (POMW ) carapace width relationships: POMW = −4.00 + 1.46(PRMW ), where PRMW < 36.1 mm, and POMW = 48.83 + 1.17(PRMW − 36.1), where PRMW ≥ 36.1 mm. Received July 23, 2012; accepted September 13, 2012

International audience; Recent increases in emergent infectious diseases have raised concerns about the sustainability of some marine species. The complexity and expense of studying diseases in marine systems often dictate that conservation and management decisions are made without quantitative data on population-level impacts of disease. Mark–recapture is a powerful, underutilized, tool for calculating impacts of disease on population size and structure, even in the absence of etiological information. We applied logistic regression models to mark–recapture data to obtain estimates of disease-associated mortality rates in three commercially important marine species: snow crab (Chionoecetes opilio) in Newfoundland, Canada, that experience sporadic epizootics of bitter crab disease; striped bass (Morone saxatilis) in the Chesapeake Bay, USA, that experience chronic dermal and visceral mycobacteriosis; and American lobster (Homarus americanus) in the Southern New England stock, that experience chronic epizootic shell disease. All three diseases decreased survival of diseased hosts. Survival of diseased adult male crabs was 1% (0.003–0.022, 95% CI) that of uninfected crabs indicating nearly complete mortality of infected crabs in this life stage. Survival of moderately and severely diseased striped bass (which comprised 15% and 11% of the population, respectively) was 84% (70–100%, 95% CI), and 54% (42–68%, 95% CI) that of healthy striped bass. The disease-adjusted yearly natural mortality rate for striped bass was 0.29, nearly double the previously accepted value, which did not include disease. Survival of moderately and severely diseased lobsters was 30% (15–60%, 95% CI) that of healthy lobsters and survival of mildly diseased lobsters was 45% (27–75%, 95% CI) that of healthy lobsters. High disease mortality in ovigerous females may explain the poor recruitment and rapid declines observed in this population. Stock assessments should account for disease-related mortality when resource management options are evaluated.

Of the seven species in the genusChionoecetes(family Oregoniidae), the snow crabChionoecetes opilio(Fabricius, 1788) is one of the most important commercial crustacean species along with its relative, the red snow crabC. japonicusRathbun, 1932. Despite restrictions allowing male-only capture and size limits, the capture ofC. opiliois changing and management of its natural resources is required. Microsatellite markers forC. opiliothat can be used in population and management studies were isolated using 454 pyrosequencing, a cost-effective and rapid method. Among 11 172 dinucleotide microsatellites, 64 loci containing more than nine repeats of either CA or AT were selected for primer synthesis, and 49 (76.6%) primer sets producing PCR products between 100-300 bp in length were selected as candidates. Following initial experiments with four individuals ofC. opilio, 18 polymorphic loci and three monomorphic loci were selected as the final microsatellite markers for this study. In a cross-species transfer analysis of these markers using 11 crab species belonging to the families Oregoniidae, Cheiragonidae and Portunidae in the order Brachyura, two loci, Co10-nfrdi and Co36-nfrdi, were amplified by PCR from all of the tested species, while the rest of the loci were amplified in at least one of the tested species. Among the 11 tested species,Portunus trituberculatus(Miers, 1876) of the family Portunidae showed the highest transferability. The average percentage of amplification was higher in the same genus followed by in the same family rather than in different genera or families.

International audience; The Arctic is facing major environmental changes impacting marine biodiversity and ecosystem functioning. One way of assessing the responses of an ecosystem to these changes is to quantitatively study food web dynamics. Here, we used stable isotope (δ15N and δ13C) analyses of 39 Arctic marine species to investigate trophic relationships and isotopic niches of the West Greenland food web in 2000–2004. The lowest δ15N values were found for suspension feeding blue mussel (Mytilus edulis; 6.1 ‰) and the highest for polar bear (Ursus maritimus; 20.2 ‰). For δ13C, copepods (Calanus spp.) had the lowest values (−20.4 ‰) and snow crab (Chionoecetes opilio) the highest values (−15.8 ‰). Our results show that the three trophic enrichment factor (TEF) approaches used to quantify species trophic positions (fixed TEF of 3.8 and 3.4 ‰ or scaled TEF) did not generally affect trophic modelling and provided similar conclusions. Overall, the findings in this study are in good agreement with previous investigations of other Arctic marine ecosystems. Interestingly, we found little overlap of core isotopic niches used by the four investigated functional groups (mammals, seabirds, fish and invertebrates), except for seabirds and fish where an overlap of 24 % was found. These results provide new insights into species and functional group interactions, as well as into the food web structure and ecosystem functioning of an important Arctic region that can be used as a template to guide future modelling of carbon, energy and contaminant flow in the region.

The concentrations of trace metals (As, Cd, Co, Cu, Fe, Hg, Pb, and Zn) were measured in muscle and hepatopancreas of two Chionoecetes crabs (Chionoecetes japonicus and C. opilio) caught from the East/Japan Sea (EJS) in order to assess the potential health risk by the consumption of deep sea crabs. The highest metal concentrations in muscle and hepatopancreas were As and Fe, respectively, while the lowest metal concentration in two tissues was Pb. The mean concentrations of Cd, Co, Cu, Fe, and Pb in Chionoecetes crabs were one or two orders of magnitude higher in hepatopancreas than in muscles. The mean concentrations of As, Cu, and Hg in muscle and hepatopancreas were relatively higher in C. japonicus than in C. opilio. The estimated daily intakes (EDI) of all metals in muscle were below 0.1% of the provisional tolerable daily intake (PTDI) adopted by the Joint FAO/WHO Expert Committee on Food Additives. Similarly, the target hazard quotient (THQ) of all trace metals in muscle was less than 1.0. These results imply that Chionoecetes crabs caught from EJS do not have an adverse impact on the Korean health. Based on the mean metal concentrations, PTDI, and THQ, the daily maximum permissible intakes of C. japonicus and C. opilio were estimated to be approximately 240 and 410 g/day, respectively.

The Korean bottom trawl survey was conducted using a trawl designed by the National Fisheries Research and Development Institute (NFRDI). The capture efficiency and size selectivity of this trawl for snow crab Chionoecetes opilio was investigated by experimental tows. An auxiliary sampling net (underbag) was attached beneath the trawl net to capture crabs escaping under the trawl footrope. Experimental tows were made by the same vessel speed (3.4 knots) as in the bottom trawl survey, but toing time was shortened from the standard 30 min to 10 min to reduce possible trawl distortion due to the high catch rate of mud and debris in the underbag. In averaged over 17 tows conducted between 110-383 m depth, trawl efficiency of both males and females combined increased from about 10% at 20 mm (carapace width) to about 70% at 100 mm, with a width of 50% capture equal to 78 mm.

This study shows that a sharp ecosystem transition in dominant communities during the early 1990s, from finfish to crustaceans, was common to the 2 northernmost Northwest Atlantic ecosystems, the NewfoundlandLabrador shelf (NL) and the northern Gulf of St. Lawrence (nGSL). Fishery and survey data show that populations of Atlantic cod Gadus morhua, typical of most finfish species, collapsed during the late 1980s to early 1990s in both systems, while Green- land halibut Reinhardtius hippoglossoides populations changed little. Biomass of northern shrimp Pandalus borealis increased following the collapse of cod in both systems, likely due, at least in part, to release of predation pressure. Predation appeared to have relatively little effect on bio- mass of snow crab Chionoecetes opilio. Shrimp replaced capelin as the principal prey in the diet of NL cod and nGSL Greenland halibut in the mid-1990s. The contribution of shrimp to the pred- ator diets was generally highest when neither capelin nor other suitable prey (fish or squid) were available. We conclude that the NL and nGSL ecosystems are similar in form and function, differ- ing from Canadian Atlantic ecosystems further south. The implications of a change in predomi- nant forage species from capelin to shrimp in these systems are unknown, but could conveivably include changes in the pathway and efficiency of energy flow.

The effect of temperature on molting frequency and size-at-terminal molt of the snow crab Chionoecetes opilio was investigated and compared between 2 Canadian Atlantic ecosystems based on spring and summer surveys. We found that the size-at-terminal molt was directly related to temperature but that the effect of temperature was much clearer and occurred at smaller sizes for females than for males. By focusing on recently molted (new-shelled) crabs, we showed that size-at-terminal molt is conditioned by temperature over a variable number of instars and intermolt periods leading up to the terminal molt. Crabs of both sexes larger than about 50 mm carapace width (CW), on annual molting schedules, sometimes skipped a molt. The frequency of skip-molting differed between the areas and sexes, and was directly related to size and in versely related to temperature. We develop a hypothesis to explain the relationships of terminal size with temperature and molting frequency that is consistent with life-history theory and snow crab bioenergetics and considers differences between the sexes. The implications to natural mortality and recruitment to fisheries are also discussed.

Snow crabs Chionoecetes opilio are found in many subarctic ecosystems, where they are important components of marine food webs and support large commercial fisheries. Snow crab abundance is highly variable, but the causes of large changes in year-class strength are poorly known. We used a regression approach to examine the effects of snow crab spawning stock bio- mass, bottom water temperature, cold area or sea ice extent, and predation by Pacific cod Gadus macrocephalus or Atlantic cod G. morhua on snow crab recruitment in each of 3 ecosystems: the eastern Bering Sea, the Newfoundland-Labrador Shelf, and the southern Gulf of St. Lawrence. Comparing results across systems showed that cold ocean conditions during early life history were associated with increased snow crab recruitment or recruitment indices in all 3 ecosystems. How- ever, we found no consistent evidence that spawning stock or gadid biomasses were significantly related to subsequent snow crab recruitment. Our results underscore the value of comparing mul- tiple ecosystems and demonstrate the importance of ocean conditions in driving variability in snow crab populations.

We examined spatial and temporal relationships between snow crab Chionocetes opilio, shrimp Pandalus spp., Atlantic cod Gadus morhua and the environment (depth, tempera- ture and salinity) on the Newfoundland-Labrador Shelf from 1995 to 2009 using autumn multi- species trawl survey data. First, the core habitat of snow crab and shrimp was determined based on cumulative distribution functions of species abundance over depth and bottom temperature. On average, this method predicted the presence of crab and shrimp at 95 and 99% of trawl loca- tions, respectively, and indicated 90% of crab and shrimp inhabited temperature ranges of �1 to 4 and 0 to 4°C and depths of 100 to 500 and 150 to 450 m, respectively. Then geographically weighted regressions, based on trawl stations where species presence was predicted, indicated spatial non-stationarity between invertebrates and explanatory variables at scales

Sufficient oceanographic measurements have been made in recent years to describe the latitudinal variation in the physics of the eastern Bering Sea shelf and the potential impact of climate change on the species assemblages in the two ecosystems (north and south). Many of the predicted ecosystem changes will result from alterations in the timing and extent of sea ice. It is predicted that the sea ice in the northern Bering Sea will be less common in May, but will continue to be extensive through April. In contrast, the southern shelf will have, on average, much less sea ice than currently observed, but with large interannual and multiyear variability until at least 2050. Thus, even under current climate warming scenarios, bottom temperatures on the northern shelf will remain cold. Based on biophysical measurements, the southern and northern ecosystems were divided by a North–South Transition at ∼60°N. The northern middle shelf was characterized by a freshwater lens at the surface, cold bottom temperatures, and a thicker pycnocline than found on the southern shelf. Subsurface phytoplankton blooms were common. In contrast, the southern shelf stratification was largely determined by temperature alone; the pycnocline was thin (often Calanus spp. and Thysanoessa spp.) of planktivorous fish, seabirds and whales. The response of commercially and ecologically important fish species is predicted to vary. Some species of fish (e.g., juvenile sockeye salmon, Oncorhynchus nerka ) may expand their summer range into the northern Bering Sea; some (e.g., pink salmon, O. gorbuscha ) may increase in abundance while still other species (e.g., walleye pollock and arrowtooth flounder; Theragra chalcogramma and Atheresthes stomias , respectively) are unlikely to become common in the north. The projected warming of the southern shelf will limit the distribution of arctic species (e.g., snow crab, Chionoecetes opilio ) to the northern shelf and will likely permit expansion of subarctic species into the southern Bering Sea. The distribution and abundance of baleen whales will respond to shifts in prey availability; for instance, if prey are advected northward from the southeastern Bering Sea, an extension of range and an increase in seasonally migratory baleen whale numbers is anticipated. Thus, alteration of this ecosystem in response to climate change is expected to result in something other than a simple northward shift in the distribution of all species.

Hematodinium species are parasitic dinoflagellates known to infect a growing number of marine crustacean genera from around the world, many of which support important commercial fisheries. Affected hosts undergo dramatic pathological alterations to their organs, tissues and hemolymph. There are no known control measures for this disease. Economically important wild fished hosts known to be susceptible to Hematodinium spp. include Tanner crabs Chionoecetes bairdi and snow crabs Chionoecetes opilio in the Northeast Pacific and Atlantic Oceans, blue crabs Callinectes sapidus from the Atlantic and Gulf coasts of the United States, and Norway lobsters Nephrops norvegicus and Edible crabs Cancer pagurus from European waters. In recent years, several farmed aquatic crustaceans in China have also been negatively impacted by Hematodinium-associated diseases, likely representing an emerging issue for that expanding industry. Molecular sequence data indicates that there are two species, Hematodinium perezi, and a second species, currently unnamed, infecting hosts from the Northern Hemisphere. Three subtly different H. perezi genotypes have been identified infecting hosts from different geographical locations: the English Channel, the eastern seaboard of the United States and Gulf of Mexico, and eastern China. Genotypic variability between isolates of the Hematodinium sp. infecting hosts from the North Atlantic and North Pacific has also been reported, though it is unclear whether there is any correlation with host or location. Identification of Hematodinium species (and genotypes of H. perezi) is largely dependent upon geographical location, rather than host species. However this is not exclusive, as both Hematodinium species can be found infecting multiple species from same location, as is the case in the English Channel.

We investigated current diets of the six most abundant benthic fish in the northern Bering Sea. Our objective was to explore feeding strategies and potential competition with other top predators as ecosystem changes occur in the northern Bering Sea ecosystem. Our approach used stomach content data collected from field sampling during spring 2006 and 2007. Calanoid copepods and ampeliscid amphipods were important prey of Arctic cod (Boreogadus saida) but in different proportions depending upon fish size, feeding location, and local environmental conditions. Snailfish (Liparidae) occupied a broad niche and fed on a variety of benthic amphipods. Arctic alligatorfish (Ulcina olrikii) and Arctic staghorn sculpin (Gymnocanthus tricuspis) consumed ampeliscid amphipods predominantly. Shorthorn sculpin (Myoxocephalus scorpius) had a less-diverse diet, with snow crab (Chionoecetes opilio) most important by weight. Finally, all Bering flounder (Hippoglossoides robustus) sampled had empty stomachs. Our results indicate that ampeliscid amphipods, which have high biomass in the central region of the northern Bering Sea, are the most important prey for the dominant groundfish in the Chirikov Basin. Generally, all dominant benthic fish in the northern Bering Sea had narrow feeding niches, except snailfish. High diet overlap was found among many of the fish species, including Arctic cod and snailfish, snailfish and Arctic alligatorfish, and Arctic alligatorfish and Arctic staghorn sculpin. These findings are consistent with a relatively short food chain for benthic fish that are for the most part specialized feeders with narrow preferences for food and may be affected by changes in benthic prey distributions.

Both red snow crab (Chionoecetes japonicus Rathbun, 1932) and snow crab (Chionoecetes opilio Fabricius, 1788) are commercially important species in Korea. The geographical ranges of the two species overlap in the East Sea, where both species are fished commercially. Morphological identification of the two species and putative hybrids can be difficult because of their overlapping morphological characteristics. The presence of putative hybrids can affect the total allowable catch (TAC) of C. japonicus and C. opilio, and causes problems managing C. japonicus and C. opilio wild resources. To date, however, no natural hybridization has been reported between C. japonicus and C. opilio, despite their overlapping distributions along the coast of the East Sea. In this study, the internal transcribed spacer (ITS) region of major ribosomal RNA genes from the nuclear genome and the cytochrome oxidase I (CO I) gene from the mitochondrial genome were sequenced to determine whether natural hybridization occurs between the two species. Our results revealed that all putative hybrids identified using morphological traits had two distinct types of ITS sequences corresponding to those of both parental species. Mitochondrial CO I gene sequencing showed that all putative hybrids had sequences identical to C. japonicus. A genotyping assay based on single nucleotide polymorphisms in the ITS1 region and the CO I gene produced the most efficient and accurate identification of all hybrid individuals. Molecular data clearly demonstrate that natural hybridization does occur between C. japonicus and C. opilio, but only with C. japonicus as the maternal parent.

Thalassarche melanophrys (Black-browed Albatross) has rarely been sighted in the northwest Atlantic, with fewer than 30 anecdotal and fewer than 10 confirmed sightings spanning the West Indies north to Greenland. On 8 August 2009, a Black-browed Albatross was observed from a longliner conducting an exploratory Chionoecetes opilio (Snow Crab) survey, off the coast of northern Labrador. This sighting currently represents the most northerly record for continental North America. The only more northerly records are two specimens seen off Greenland. Black-browed Albatrosses have been seen more frequently, though rarely, in the eastern North Atlantic, while they have yet to be documented in the north Pacific. Given the higher frequency of sightings along the European coast, it may be that the majority of Black-browed Albatrosses crossing the equator are traveling up the African coast. Black-browed sightings on the Atlantic coast of North America therefore may originate in northern Europe, or from birds ...

Snow crab ( Chionoecetes opilio ) populations have fluctuated cyclically in eastern Canada and the eastern Bering Sea, where recruitment to the mature female pool has occurred over a period of three decades (1978–2007) in pulses with a mean period of 7 years. It has been hypothesized that this was the result of a parent–offspring relation between sequentially linked strong cohorts of mature primiparous females, which requires that periodicity matches the time lapsed between egg extrusion by the maternal broodstock and the offspring reaching maturity. We show that female age at maturity (post-settlement) varies between 4.5 and 7.5 years, with most females maturing at 5.5–6.5 years (7–8 years after egg extrusion). Pulses of female recruitment to the mature population do not show a latitudinal trend, consistent with uniformity in age-at-maturity. Results of tracking crab abundance and size–frequency distributions in cod stomach and trawl samples between successive pulses of the cycle are consistent with the hypothesis of serial linkage among pulses. Periodicity is reflected in trends of clutch fullness and average shell condition and in the negative correlation between the strength of primiparous female cohorts and the mean size of their members.

The snow crab (Chionoecetes opilio) shells have potential important economical and industrial applications due to theirchemical composition. They have a high content of protein (34.2% dw) and essential amino acids; they also have fat (17.1% dw), with a high proportion of ω3 polyunsaturated fatty acids. About 28.5% dw corresponds to ash (calcium, phosphorous, and magnesium are the major minerals). The mean concentrations of vitamin E, astaxantin, and β-carotene were 23.3, 9.49, and 0.2 mg/100 g dw, respectively. Results presented in this study indicate that snow crab by-products may serve as excellent nutritional components for future applications in the health and food sectors. Los caparazones del cangrejo de las nieves (Chionoecetes opilio) pueden tener aplicaciones industriales y economicas potencialmente importantes debido a su composicion quimica. En su composicion destaca el elevado contenido en proteinas (34,2% ms) y aminoacidos esenciales, en lipidos totales (17,1% ms), con una elevada proporcion d...

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.

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.

Entanglements of large whales in commercial fisheries in Newfoundland and Labrador, Canada, have been consistently recorded since 1979, as part of a program aimed at releasing captured animals and reducing costs to fishermen. This data set represented an opportunity to identify fisheries posing particular entanglement risks to local whale populations. Data were assessed over the periods 1979–1992 and 1993–2008, corresponding to distinct phases in fisheries distribution and intensity. Between 1979 and 2008, 1,209 large whale entanglements were recorded in Newfoundland and Labrador. These were mostly humpback whales (Megaptera novaeangliae; 80%) and minke whales (Balaenoptera acutorostrata; 15%). Dramatic declines in reported inshore whale entanglement rates were observed following the 1992 moratorium on Atlantic cod (Gadus morhua) fisheries. Recently, more entanglements have been reported further offshore, largely due to expansion of fisheries targeting snow crab (Chionoecetes opilio). For all whale species, entanglement 1 This article is dedicated to Dr. Jon Lien (1939–2010), who was instrumental in setting up the Large Whale Entrapment Program through Memorial University’s Whale Research Group, and who for more than 30 yr worked tirelessly on behalf of both whales and fishermen in Newfoundland and Labrador. A large proportion of the data described here was gathered by Jon and his associates, and his role in resolving whale entanglements in Newfoundland fisheries cannot be overstated. He will be sorely missed.

In much of the northwest Atlantic Ocean, commercially important snow crab Chionoe- cetes opilio stocks have increased in abundance since the decline and collapse of major groundfish stocks such as Atlantic cod Gadus morhua. We examined 3 hypotheses to explain variation in the abundance of snow crabs across 10 regions: (1) climate control of both species, (2) top-down control of snow crab by cod and (3) bottom-up control of cod by snow crab. We tested these hypotheses by analyzing time series data of cod and crab abundance indices and temperature via meta-analysis of full and partial correlation coefficients. We found that temperature had an opposing effect on the 2 species: snow crab abundance was negatively correlated with temperature at 7 to 10 yr lags, whereas cod and temperature were positively related at 1 to 7 yr lags. Controlling for the effect of temperature, our meta-analysis revealed significant negative correlations of snow crab and cod abundance, with cod leading snow crab by up to a 5 yr lag. This suggests a top-down effect on older juvenile and subadult snow crab. We found no evidence of a bottom-up effect of snow crab on cod. Negative correlations between cod and crab abundance were observed both at the warmer and colder portions of their ranges. These results suggest that snow crab abundance is largely influenced by temperature during the early postsettlement years and becomes increasingly regulated by top-down mechanisms during the years approaching fishery recruitment. The method presented in this paper is generally useful to test ecological hypotheses from time series data, particularly where multiple causal mechanisms are suspected.

We relate the spatial variability in the distribution of benthic taxa of the Beaufort Sea to oceanographic characteristics of their habitat with the goal of illustrating potential mechanisms linking climate change to Arctic marine communities. Offshore fish of the Beaufort Sea have not been surveyed since 1977 and no synchronous measures of fish distribution and the oceanographic characteristics of their habitat have been made previously. A survey was conducted during August 2008 in the western Beaufort Sea, Alaska. The distribution and abundance of benthic fish and invertebrates were assessed with standard bottom trawl survey methods. Oceanographic data were collected at each trawl station and at several locations between stations. The dominant benthic taxa, Polar cod (Boreogadus saida), eelpouts (Lycodes sp.), and snow crab (Chionoecetes opilio) were associated with cold ( 33) water found offshore of the shelf break, derived from the Chukchi Sea. These waters are expected to be high in secondary productivity, such that we hypothesize that the distribution of fish and crab was driven by conditions favorable for successful foraging. Predictions of the impacts of climate change require an understanding of the mechanisms linking the distribution and abundance of marine organisms to their oceanographic habitat. Our study documents the association of dominant benthic fish and invertebrates of the Beaufort Sea with specific water mass types and is thus a step toward this understanding.

It has been found, with reference to the data of trawl survey and literature, that, in the Sea of Japan, the Northern boundary of the area of the elongated sculpin Alcichthys elongatus is the central part of the Tatar Strait. During the year, the elongated sculpin occurs at depths from 7 to 650 m. Its highest concentration forms during the feeding period. At this time Alcichthys elongatus stays up to depths 253 m but prefers the range of 40–100 m. It winters below the 50 m isobath, mainly in the lower part of the shelf and in the upper section of the continental slope. Being an eurythermal species, the elongated sculpin occurs in a wide range of temperature (from −1.6 to 17.7°C). However, most specimens prefer waters with slightly positive temperature. Juveniles prefer the warm water layers. Males are larger than females but the latter dominate in catches. According to the kind of diet A. elongatus, it is a benthoichtyophage consuming predominantly decapods (mostly juveniles of Chionoecetes opilio) and small fish. In summer, the value of daily ration is 3.0% of the body weight. In the north-western part of the Sea of Japan, A. elongatus may be characterized as a common species with a low but stable abundance.

Spermatogenesis and physiological maturity in the Barents Sea red king crab and snow crab were studied using histological methods. Samples of the red king crab and snow crab were collected between 1994–2000 and 2004–2008, respectively. The development of the germ cells in red king crab and snow crab testes is accompanied by the formation of spermatophores, which indicate physiological maturity. The smallest red king crabs with spermatophores were of 65 mm carapace length (CL). Spermatophores were found in 95% of 70–79 mm CL crabs and in all specimens with CL exceeding 80 mm. Spermatogenesis in red king crab males occupies approximately two years and is season-dependent. The Barents Sea snow crabs reach physiological maturity at 43 mm carapace width (CW). In the samples analysed, all males with CW exceeding 45 mm contained spermatophores. Unlike the red king crab, the production of ripe germ cells in the snow crab is continuous rather than associated with a definite season. Physiologically mature ...

Comparative fishing experiments were conducted to evaluate the selectivity and efficiency of escape mechanisms installed in traditional snow crab (Chionoecetes opilio) traps. Performance of the different trap types (control, traditional, experimental) were compared on the basis of size distribution caught, numbers of animals per trap haul (CPUEN), and size selectivity. The study demonstrated that either 95 or 100 mm diameter escape mechanisms installed into traditional 14.0 cm mesh traps resulted in 38–47% fewer undersized pre-recruit ( 101 mm CW). Qualitative underwater behavioural observations were also conducted for snow crab in response to baited traps, corroborating current understandings as well as documenting new observations related to crab behaviour during capture, escape, haul-back, and interspecific competition with Atlantic cod (Gadus morhua).

Snow crab (Chionoecetes opilio) proteins have been recognized as an important source of both food and occupational allergens. While snow crab causes a significant occupational allergy, only one novel allergen has recently been fully characterized. The muscle proteins from snow crab legs were profiled by SDS-PAGE. Several of these proteins were characterized using tandem mass spectrometry. Five proteins were identified; sarcoplasmic Ca-binding (20 kDa), arginine kinase (40), troponin (23 kDa) and α-actine (42 kDa) and smooth endoplasmic reticulum Ca2+ATPase (113 kDa). Immunoblotting using serum of sixteen allergic patients resulted in strong reactivity with the 40-kDa protein in seven patients (43%). This protein was purified by chromatography and subsequently de novo sequenced using matrix assisted laser desorption ionization and electrospray tandem mass spectrometry. We identified a second important allergen, arginine kinase, in snow crab, designated Chi o 3. Based on identity and homology analysis, using bioinformatics tools, a signature peptide was identified as a chemical surrogate for arginine kinase. The suitability of this signature peptide was tested for analytically representing the arginine kinase, by performing a multi-reaction monitoring tandem mass spectrometry approach on actual air filter samples collected from a simulated crab processing plant.

Mullowney, D. R., Dawe, E. G., Morado, J. F., and Cawthorn, R. J. 2011. Sources of variability in prevalence and distribution of bitter crab disease in snow crab (Chionoecetes opilio) along the northeast coast of Newfoundland. – ICES Journal of Marine Science, 68: . Bitter crab disease (BCD), caused by a parasitic dinoflagellate of the genus Hematodinium, is a source of mortality in Newfoundland and Labrador snow crab (Chionoecetes opilio). Prevalence and distribution patterns have been spatially and temporally variable since the discovery of BCD in 1990, and controlling factors are poorly understood. Data from a long-term trap survey in two bays along the northeast coast of Newfoundland are analysed, investigating the influences and interactions of various biotic and abiotic factors over BCD. Factors examined include host size and density, temperature, salinity, and depth. The density of small to medium-sized snow crabs was directly related to prevalence and distribution of BCD, whereas all other factors had either an indirect or no effect. Further, much of the spatio-temporal variability in disease expression is a function of variability in host productivity, growth, and movement. The study also considers the impacts BCD can exert on the commercial fishery, and the potential for predicting intermediate to long-term recruitment potential based on BCD prevalence levels.

未成熟で市場価値の低い水ガニのズワイガニ漁期中の入網数とリリース直後の生残率を推定した。底曳網で漁獲された水ガニを篭に入れ，海底に約 6 時間浸漬した後に再び回収し生死を判断した。京都府沖合での水ガニ平均入網数は，2006～08 年の標本船日誌から 168,400 個体と推定され，成熟で市場価値の高い雄ガニの約 1.7 倍であった。生残率は甲幅 90～109 mm では 14.8～95.9%, 110～129 mm では 5.0～89.8%, 130 mm 以上では 0～62.5% と推定された。水ガニ漁期（1～3 月）に水ガニをリリースした場合，平均生残率は 83.6% と高く，雄ガニの増加に寄与すると考えられた。

Lipofuscin levels were investigated in snow crabs (Chionoecetes opilio) to assess the applicability of lipofuscin quantification as an age determining tool for this species. Localization and quantification of lipofuscin granules in the olfactory lobe cell mass (OLCM) of the brain were conducted by confocal microscopy and image analysis. The majority of immature crabs had no detectable lipofuscin. Crabs with a dirty carapace condition (an indication of greater age) had more lipofuscin (in terms of granule density, area fraction, and mean granule size) than crabs with a clean carapace condition; however, the amount of lipofuscin was much lower than that in more temperate species. Lipofuscin content was positively correlated with carapace size among crabs with a clean carapace but not among crabs with a dirty carapace. No correlation was observed between average lipofuscin granule fluorescent intensity and carapace width. OLCM neuron characteristics were also investigated. An inverse relationship was observed between neuron density and carapace width although it is unknown if this density reduction is due to a loss of neurons, an increase in size of the structures, or both. Furthermore, a positive relationship was observed between neuron size and carapace width. The range of neuron size also increased in larger crabs, suggesting the presence of mitotically active cells in the OLCM. Although lipofuscin levels were higher in dirty carapace condition (presumably older) crabs than in clean carapace crabs and increased with size (in mature, clean carapace snow crabs), the lack of detectable lipofuscin in most immature crabs, generally low levels of lipofuscin in mature crabs, and lack of increase with size in older (dirty carapace) crabs limits the applicability of this age estimation tool for this species.

Abstract Snow crabs, Chionoecetes spp., are among the commercially most important species of Decapoda in the world, and proper stock assessment and management are required for their sustainable use. In the present study, morphological characteristics of three snow crabs, Chionoecetes japonicus, Chionoecetes opilio and a hybrid form exhibiting characteristics intermediate between those of the parent species, Chionoecetes japonicus/opilio, have been compared. The ratio of carapace length including rostral horn (CL(RL)) to carapace width (CW) in C. japonicus, C. opilio, and the C. japonicus/opilio hybrid was 0.973 ± 0.020, 0.983 ± 0.019, and 0.956 ± 0.019, respectively. The only significant difference in regression slope among the three crabs, was between CW and chela height (CH), indicating that at a given size, the hybrid form is the fastest in the growth of chela height in relation to carapace width. In C. japonicus and C. opilio, the relationship between CW and total weight (TW) was significantly negatively allometric, while in the hybrids, it was significantly positively allometric. This indicates that at a given size, the hybrid form is heavier than the others.

Several specimens of the snow crab Chionoecetes opilio (O. Fabricius, 1788) were found in trawl catches in October 2012 during the expedition of the Murmansk Marine Biological Institute (MMBI) on the R/V Dalnie Zelentsy to the southwestern part of the Kara Sea. This species has not so far been recorded from the Kara Sea. The possible means of the invasion of the snow crab into the Barents and Kara seas are discussed.

The causes of the appearance of large blue king crabs (Paralithodes platypus) in Peter the Great Bay for the last decade are discussed. This species is an important commercial resource in the waters of Russian Far Eastern seas, and its general concentrations are related mainly to the sublittoral and upper bathyal zones of the northwestern Bering Sea and the northern Sea of Okhotsk. Until recently, this species has been observed in areas along the continental coast of the northwestern Sea of Japan up to the Peter the Great Bay, where it incidentally showed up in red king crab (P. camtschaticus) and snow crab (Chionoecetes opilio) catches but was also commercially used. This area was considered as the southern periphery of the species range. Since the late 1990s, both male and female blue king crabs have been recorded in trawl and trap catches during research works conducted within the Peter the Great Bay. Since 2002, any commercial catches of shelf crab species are prohibited in the waters south of 47°20′ N because of a dramatic decline in their populations. Since then all the illegally caught crabs, including blue king crabs that are seized live from poachers, are released back into the water in certain places of the bay. In total, at least 29 503 blue king crabs, including egg-bearing females, were released within the period from 2002 to November 2009. At present, the overall blue king crab abundance in Peter the Great Bay, estimated based on the trap catches over an area of 7048 km2, is 50500, the abundance of commercial-size males (with a carapace width over 130 mm) is 7500, and the male to female ratio is 1.00: 1.35. The increase in the blue king crab population observed in the bay is the result of the immigration of mature and viable individuals from other areas of its range. After this “uncontrolled introduction” blue king crabs adapted to new conditions, and then began breeding and spreading over the entire area of the bay.

This study examined the effects of ration and temperature on the molt of male adolescent snow crab Chionoecetes opilio (O. Fabricius, 1788). In one experiment, crabs were exposed to 1 of 4 treatments, 2 levels of ration and 2 levels of temperature. In a second experiment, all crabs were fed and a 4-level factor was addressed in which temperature was held constant as in experiment 1 (2 levels) or switched from one level to the other. Food consumption declined significantly and at a similar rate over time at both temperatures, several weeks before molt took place. Larger crabs molted to morphometric maturity in a greater proportion with no influence of ration or temperature. Smaller crabs also molted earlier than larger crabs. Temperature had a marked effect on the timing of molt, with crabs kept at a higher temperature molting 1 mo earlier and crabs exposed to shifted temperatures, molting midway between the two other groups. Body density decreased markedly at ecdysis, but was also influenced by r...

Five decapod crustacean species were examined for presence of the parasitic dinoflagellate Hematodinium spp. (Alveolata, Syndinea) by morphological methods (colour and pleopod methods) as well as by PCR and nested PCR with Hematodinium-specific primers. Nephrops norvegicus, Pagurus bernhardus and Liocarcinus depurator were sampled by trawling in Danish waters and Chionoecetes opilio and Hyas araneus were sampled by trapping off the west coast of Greenland. The existence of Hematodinium has not previoiusly been documented in Danish waters, but it was detected in all 3 decapod species examined in the present study. Hematodinium sp. was also detected for the first time in H. araneus and the existence of Hematodinium sp. in Greenlandic C. opilio was documented by PCR. Analyses of 26 Hematodinium sp. ITS1 sequences, including sequences from all 5 host species sampled, revealed more than 95% sequence similarity between 24 of the sequences. Two Hematodinium sp. ITS1 sequences from C. opilio were only 81% similar to the 24 other ITS1 sequences. The nested PCR approach resulted in the highest reported percentages of positive samples for Hematodinium sp.in the hosts investigated (between 45 and 87.5%). However, no decapods were found to be infected with Hematodinium sp. based on morphological methods. Consequently, Hematodinium sp. may be more common than previously believed, and, assuming that the DNA found originated from viable and infectious parasite cells, infections may not always be fatal. We suggest that the hosts investigated may have been subject to latent infections that could develop into a fatal disease only if the hosts were physiologically stressed due to other factors.

Changes in species abundances caused by climatic variability have long been linked to alterations in community composition, species interactions and maintenance of biodiversity in marine ecosystems. Here we use multivariate regression tree (MRT) analyses to quantify how changes in species abundances and environmental variability contributed to observed patterns of community composition in the Gulf of St. Lawrence during 2 contrasting periods (the cooler and less saline period 1991 to 1995 and the warmer and more saline period 1997 to 2003). Broad-scale patterns of commu- nity composition in both periods were consistently explained by the depth and salinity of the benthic environment, but biological factors differed. In the cold period, the previous year's catches of snow crab Chionoecetes opilio and northern shrimp (mainly Pandalus borealis) were most important, while in the warm period the previous year's catch of Atlantic cod Gadus morhua dominated. MRT models further identified spatially discrete areas where communities are characterized by relatively high abundances of these species. These results indicate that environmental variability leads to dynamic and spatially explicit responses not only of single species, but of marine communities. Applications of ecosystem management in the face of climate change must take this into account.