Tanner Crab Chionoecetes Bairdi Research Articles

Milky hemolymph syndrome (MHS) associated with a virus in tanner crab Chionoecetes bairdi off the Pacific coast of Kamchatka

Milky hemolymph syndrome (MHS) caused by a bacilliform virus (BV) was found in tanner crab Chionoecetes bairdi in the shelf zone of Kamchatka. The prevalence of the disease varied from 0.18 to 1.02%. A total lesion of the cells of the interstitial connective tissue and the connective tissue component of all internal organs was noted, which was expressed in the hypertrophy of their nuclei. In addition, hypertrophy of fixed phagocytes and circulating hemocytes was noted. Ultrastructural analysis of the tissues confirmed that in the interstitial connective tissue of pathologically altered organs, virus particles of two morphotypes were found - rod-shaped and globular. In the cytoplasm of infected cells, bands of microtubules formed near where viral particles were concentrated. In the area of contacts at the poles of microtubules, successive stages of the transformation of rod-shaped viruses into globular viruses was observed. The bacilliform virus that infects C. bairdi is structurally very similar to CoBV found in Chionoecetes opilio. Structural features are characteristic of representatives of fam. Nimaviridae. The molecular data obtained suggest that the virus causing MHS in C. bairdi is systematically very close, if not identical, to CoBV.

First detection of Hematodinium sp. In spiny king crab Paralithodes brevipes, and new geographic areas for the parasite in tanner crab Chionoecetes bairdi, and red king crab Paralithodes camtschaticus

A parasitic dinoflagellate of the genus Hematodinium was found off the Pacific coast of Kamchatka in three species of crabs: red king crab Paralithodes camtschaticus, tanner crab Chionoecetes bairdi, and spiny king crab Paralithodes brevipes. This is the first detection of Hematodinium in spiny king crab. The results of the genetic analysis showed that the pathogen found in P. brevipes, P. camtschaticus, and C bairdi from the Avacha and Kronotsky bays off the Pacific coast of Kamchatka was the same or very close to the Hematodinium sp., which infects many species of crustaceans in the Northern Hemisphere. The prevalence of infection was 0.2% for tanner crabs and 2.7% for red king crabs. Due to a limited sample size, we were unable to calculate the prevalence for spiny king crabs and female red king crabs. Both the macroscopic and microscopic signs of the pathology were similar in all diseased crabs. The differences in the micromorphology of the Hematodinium cells we found in the three crab species, including the presence or absence of trichocysts, the shape of the plasmodia, and the structure of pore complexes, are most likely related to the life cycle and the physiology of the parasite. The results of the genetic analysis showed that the pathogen found in P. brevipes, P. camtschaticus, and C. bairdi from the Avacha and Kronotsky bays of the Pacific coast of Kamchatka was the same or very close to the Hematodinium sp., which infects many species of crustaceans in the Northern Hemisphere.

On reproductive biology of tanner crab Chionoecetes bairdi Rathbun, 1924 (Crustacea, Decapoda) females at southeastern Kamchatka

Fecundity and some other reproductive characteristics of tanner crab Chionoecetes bairdi females are studied for the first time in the area at southeastern Kamchatka on the materials collected in spring and summer aboard research vessels (in 2016 and 2019) and fishing boats (in 2020). The females with new eggs prevailed in the catches. The size of functional sexual maturity was determined as 79 mm. The implemented fertility was estimated as 93.4 ± 28.1.103 eggs in 2016 and 115.7 ± 24.5.103 eggs in 2019, on average. Reproductive effort and K/r-coefficient were evaluated; their relatively high values confirmed r-strategy of tanner crab reproduction.

CURRENT STATE OF STOCK FOR TANNER CRAB CHIONOECETES BAIRDI RATHBUN, 1924 (CRUSTACEA, DECAPODA) AT THE SOUTH-EASTERN COAST OF KAMCHATKA

Tanner crab Chionoecetes bairdi is the highly valuable object of commercial fishery dwelling in the seas surrounding Kamchatka Peninsula. Its landings started at the southeastern coast of Kamchatka in early 1980s and continued till 2009, when the fishery was stopped by reasons independent on the stock state. It was launched again in 2017. Now the species is landed mostly in the Petropavlovskaya fishery subzone (62 % of the total allowable catch of tanner crab in Russia in 2019), whereas its stocks at southwestern Kamchatka and in the northwestern Bering Sea are rather low. Modern condition of the tanner crab population and its distribution at southeastern Kamchatka are considered on the data of the trap surveys conducted in spring and summer of 2012 and 2018. Between these years, commercial males of these species spread wider at southeastern Kamchatka and formed commercial aggregations in the northern Avachinsky Bay and in the southern and central parts of the Kronotsky Bay, but were rare southward from Cape Povorotny. They became larger: while size of the males varied in the range 50–170 mm in both years, the males with the carapace width < 120 mm prevailed in 2012, but the large-sized males with commercial size were more numerous in 2018. Percentage of the females in the catches was low both in 2012 and 2018 that is typical for the trap catches. The crabs at the 3rd stage of molting dominated both in May and August of 2012 and 2018. Injury level of the commercial males was rather high and increased from 2012 to 2018 in 8 %. Good current condition of the tanner crab population at southeastern Kamchatka is concluded.

First record of the larvae of tanner crab Chionoecetes bairdi in the Chukchi Sea: A future northward expansion in the Arctic?

In the Bering Sea, warming and reduction of summer sea-ice cover are driving species ranges towards the Arctic. Tanner crab, Chionoecetes bairdi, is a commercially important species in the SE Bering Sea with a northerly range margin in 62ºN. In this paper, using plankton samples collected in the Pacific sub-Arctic/Arctic sector during summer, we report for the first time the presence of larval stages (zoea II) of C. bairdi far from its northern limit of the distribution, in the south of St. Lawrence Island during 1991, and even crossing the Bering Strait into the Chukchi Sea during 1992. We suggest that the long planktonic phase (3–5 months), in combination with the oceanographic circulation, may facilitate eventual long-distance transport.

Temperature-Dependent Growth of Early Juvenile Southern Tanner CrabChionoecetes bairdi: Implications for Cold Pool Effects and Climate Change in the Southeastern Bering Sea

Temperature strongly influences the growth of crustaceans and directly controls distribution. Despite being commercially important, there are no data on temperature effects upon growth in newly settled southern Tanner crab Chionoecetes bairdi. Recently settled crabs were reared through three consecutive molts, both individually and in groups, at four different temperatures; 2°C, 6°C, 9°C, and 12°C. Survival was higher for crabs grown individually (92%) than those in groups (66%) owing to cannibalism, particularly during molting. There were no temperature effects on survival. Growth rate (mm/day) increased linearly with temperature, a product of exponential decline in intermolt period with increasing temperature and amolt increment that was relatively constant across temperatures. Growth rate, intermolt period, and growth increment did not differ between crabs grown singly or in groups. These data suggest that growth in 0 y aged southern Tanner crabs is strongly inhibited at temperatures less than 2°C. A small mesh beam trawl survey was conducted in the southeast Bering Sea during September 2012, a year when a cold pool (<2°C bottom water) dominated the middle shelf. Southern Tanner crab less than 12 mm (carapace width) were concentrated just north of the Alaska Peninsula and along the outer shelf where bottom water was more than 2°C, but largely absent from the middle shelf. In contrast, adult southern Tanner crabs were widely distributed across the middle and outer shelves. It was hypothesized that early juvenile southern Tanner growth is inhibited by cold pool conditions, prolonging vulnerability to predation, and reducing survival. In the future, if sea temperature rises and sea ice is diminished, less frequent and less intense cold pool events may lead to increased persistence of thermally suitable juvenile southern Tanner crab habitat across the southeastern Bering Sea middle shelf region.

The thermotropic behavior and fatty radical composition of major phospholipids of the tanner crab Chionoecetes bairdi Rathbun, 1924

This study examines the fatty radical (FR) composition and heat-induced crystalline to liquidcrystalline phase transitions of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) from the gills, hepatopancreas, gonads, and muscle of the tanner crab Chionoecetes bairdi, which was collected in the summer at a near-bottom water temperature of 2.8°C. The location of the PC and PE thermograms below 2.8°C indicates the functionally optimal liquid crystalline state of the membrane lipid matrix. The proximity of the thermogram profiles of PC and PE from the different organs and tissues of C. bairdi and significant overlapping of the temperature areas of transitions (symbatic behavior) correlate with a similar composition of major FR and their total parameters in PC and PE. The obtained data point to the effective adaptation of the bairdi crab to low water temperatures and to the need for adaptive changes in the FR composition or change of habitat with increasing temperature. The thermotropic behavior of muscle PC, in which the greater part of the thermogram is in the temperature range from 2.8 to 32°C, suggests a potential for the tanner crab to adapt to increased temperatures.

Food habits of Pacific cod and walleye pollock in the northern Gulf of Alaska

Seasonal variations in the diets of Pacific cod Gadus macrocephalus and walleye pol- lock Theragra chalcogramma were examined from fish collected during 5 sampling periods from August 1998 to June 1999 in the Kodiak Island area in the Gulf of Alaska. Both species were shown to be generalist predators, eating a wide variety of fish and invertebrates. Pollock, which are limited to pelagic prey, can be considered more specialized than cod. Cod consumed 78 prey items, and pollock consumed 45 prey items, with 28 items shared by both species. Individual pol- lock, however, typically concentrated on a single prey item, while individual cod stomachs con- tained a wider variety of prey. The principal prey of Pacific cod was Tanner crab Chionoecetes bairdi, comprising >28% of the cod diet by weight. The most common prey item for walleye pol- lock was the euphausiid Thysanoessa. Over the 5 sampling periods, the prey evenness and niche width occupied by the 2 species were similar, but seasonal differences were evident.

Hematodinium sp. infection in Norway lobster Nephrops norvegicus and its effects on meat quality

Hematodinium and Hematodinium-like species have emerged in the last 3 decades as important parasitic pathogens of crustaceans worldwide, causing a significant economic loss to fisheries and related markets. In some species (notably the Tanner crab Chionoecetes bairdi), the parasite reportedly causes the cooked meat to taste bitter and aspirin-like. The bitter taste, together with the gross pathology of the infection, renders these crabs unmarketable. Surprisingly, no organoleptic tests have ever been conducted to date, and the cause for the bitter taste is still unknown. Nevertheless, it is generally assumed that the bitter taste occurs widely in cooked meats and products derived from crustaceans infected with Hematodinium. In the present study, we analysed the meat quality and organoleptic attributes after capture and during storage of Norway lobsters Nephrops norvegicus from Scottish waters that were either asymptomatic or symptomatic of patent Hematodinium infection. Results from the sensory evaluation of the cooked product indicate that tail meat from symptomatic N. norvegicus is bland in flavour and aftertaste, and more friable or sloppier in texture than meat from asymptomatic animals. As a consequence, infected meat tends to be less palatable, although surprisingly no bitter taste is reported. From an analytical point of view, tail meat from patently infected animals is at an advanced stage of autolysis, while no difference in microbial load is detected. These results suggest that Norway lobsters heavily infected with Hematodinium are of inferior marketing quality even after the tails have been cooked.

Breaking with tradition: redefining measures for diet description with a case study of the Aleutian skate Bathyraja aleutica (Gilbert 1896)

Characterization of fish diets from stomach content analysis commonly involves the calculation of multiple relative measures of prey quantity (%N,%W,%FO), and their combination in the standardized Index of Relative Importance (%IRI). Examining the underlying structure of dietary data matrices reveals interdependencies among diet measures, and obviates the advantageous use of underused prey-specific measures to diet characterization. With these interdependencies clearly realized as formal mathematical expressions, we proceed to isolate algebraically, the inherent bias in %IRI, and provide a correction for it by substituting traditional measures with prey-specific measures. The resultant new index, the Prey-Specific Index of Relative Importance (%PSIRI), is introduced and recommended to replace %IRI for its demonstrated more balanced treatment of the relative measures of prey quantity, and less erroneous behavior across taxonomic levels of identified prey. As a case study, %PSIRI was used to examine the diet of the Aleutian skate Bathyraja aleutica from specimens collected from three ecoregions of the northern Gulf of Alaska (GOA) continental shelf during June-September 2005–2007. Aleutian skate were found to primarily consume the commonly abundant benthic crustaceans, northern pink shrimp Pandalus eous and Tanner crab Chionoecetes bairdi, and secondarily consume various teleost fishes. Multivariate variance partitioning by Redundancy Analysis revealed spatially driven differences in the diet to be as influential as skate size, sex, and depth of capture. Euphausiids and other mid-water prey in the diet were strongly associated with the Shelikof Strait region during 2007 that may be explained by atypical marine climate conditions during that year.

Effect of bitter crab disease on rebuilding in Alaska Tanner crab stocks

Abstract Siddeek, M. S. M., Zheng, J., Morado, J. F., Kruse, G. H., and Bechtol, W. R. 2010. Effect of bitter crab disease on rebuilding in Alaska Tanner crab stocks. – ICES Journal of Marine Science, 67: 2027–2032. Eastern Bering Sea (EBS) Tanner crab Chionoecetes bairdi stocks were declared overfished in 1996 and were closed to commercial fishing between 1997 and 2004. Subsequent management was based on a rebuilding plan using criteria from the previous US federal fisheries management plan (FMP). Under the revised 2008 FMP, reference points changed for mature biomass (male only vs. total), as well as catch levels (total vs. retained), resulting in different rebuilding criteria. We performed a rebuilding analysis using age-, sex-, and size-structured simulations incorporating recent changes in overfishing definitions. Specifically, we compared the potential effect of additional mortality that bitter crab disease could have on rebuilding performance of lightly infected EBS and heavily infected southeast Alaska Tanner crab stocks. The results suggest that under the assumed recruitment scenario, the new control rules are adequate to rebuild the depleted lightly infected EBS stock, but not the heavily infected southeast Alaska stock.

Modifications of Cod Pots to Reduce Tanner Crab Bycatch

Recent declines in stocks of Tanner crab Chionoecetes bairdi in the Gulf of Alaska and Bering Sea and increases in the catch allocations of Pacific cod Gadus macrocephalus to vessels fishing pot gear have led to heightened concerns about Tanner crab bycatch. We conducted a laboratory study to examine the ability of two modifications in standard cod pots to reduce the catch of Tanner crabs compared with the standard pot. We also observed crab responses to a pot rigged with cod socks instead of cod triggers. In one modified pot, a slick plastic board was attached flush to the lower tunnel ramp of a pot (slick-board pot). In another modification, a webbed Z–K excluder horizontally divided the pot tunnel and three loose twine excluders were rigged on the tunnel eye (Z–K excluder pot). The plastic board on the slick-board pot deflected the current and led more crabs (32.4%) to approach side panels, rather than the tunnel eyes, compared with the standard pot (4.7%) and the Z-K excluder pot (7.9%). Both modified pots significantly reduced the reach probability P(r|a): number of crabs that reached the tunnel eye divided by the number that approached the pot. The P(r|a) for the Z–K excluder pot was also significantly lower than that for the slick-board pot. Crabs took significantly more time reaching the tunnel eyes of the slick-board pot and Z–K excluder pot than the standard pot. There was no significant difference on entry probability among the three pots. However, the mean stay duration (crab contact with the tunnel eye) significantly differed among the three pots. As a result, compared with the standard pot, both modified pots significantly reduced the catch probability P(e|a), i.e., the number of entries divided by the number of approaches. The mean P(e|a) ± 95% confidence interval (CI) was 0.05 ± 0.03 for the standard pot, 0.01 ± 0.01 for the slick-board pot, and −0.01 ± 0.01 for the Z–K excluder pot. Crabs had a significantly (0.26 ± 0.24 95% CI) higher entry probability P(e|r)—number of crabs that entered divided by the number that reached the pot—for cod socks than cod triggers and a significantly higher catch probability (0.18 ± 0.21 95% CI). Modifications with a Z–K excluder may be suitable for use in the commercial fishery to reduce bycatch of Tanner crabs.

Epibionts of the Tanner Crab Chionoecetes bairdi in the Region of Kodiak Island, Alaska

Epibionts of the Tanner Crab Chionoecetes bairdi in the Region of Kodiak Island, Alaska

Ethogram of Behavior with Emphasis on Mating for the Tanner Crab Chionoecetes bairdi Rathbun

Ethogram of Behavior with Emphasis on Mating for the Tanner Crab Chionoecetes bairdi Rathbun

ETHOGRAM OF BEHAVIOR WITH EMPHASIS ON MATING FOR THE TANNER CRAB CHIONOECETES BAIRDI RATHBUN

Laboratory observations of mating behavior of the Tanner crab Chionoecetes bairdi are described and compared with similar phenomena in other brachyuran crabs. Twenty-seven distinct actions were performed by C. bairdi during 133 matings. Seven actions-carapace caressing, bouncing, body lifting, palpating, sternum-to-sternum positioning, intromission, and pull-up-were unique to reproduction. Grasping, antennule flicking, sternum-to-sternum positioning, vigorous moving of mouthparts, and intromission were common to every complete copulation. Most primiparous females mated shortly after their maturity molt while in a new, soft-shelled condition. However, other primiparous females mated in a semihard-shelled condition as late as 21 days after the maturity molt and still produced viable zygotes. Multiparous females were able to fertilize eggs with sperm stored in their spermathecae during the preceding breeding season. Breeding recurred when males were present at the time multiparous females were receptive (during and shortly after the hatching of their eggs). Courtship, which is subtly developed, entails precopulatory attendance of the female by the male and performance of actions (body lifting, beating, and kicking) which quiet the female if she attempts to escape. Ungentle male-female interactions were infrequent when the female's exoskeletal condition was new and soft, more frequent when the female had a new semirigid exoskeleton, and prevalent when the female had an old, hard exoskeleton. In consequence, both the ability of the females to thwart breeding attempts by small and/or weak males and the occurrence of grasping marks on female exoskeletons directly increased with exoskeletal hardness. In some instances more than one male copulated with individual females. The brachyuran crab Chionoecetes bairdi Rathbun is widely distributed in the northern North Pacific Ocean between the central

Mating Frequency and Viability of Stored Sperm in the Tanner Crab Chionoecetes Bairdi (Decapoda, Majidae)

ABSTRACT In captivity the percentage of multiparous Chionoecetes bairdi that mated prior to extrusion of their annual egg clutch was 62-100% and varied with sex ratio. In test groups where one male was held with eight or fewer females, over 90% of the females mated before egg extrusion but the percentage declined when more females were present. Ten was the maximum number of females mated by a single male during one breeding season. Viable egg clutches were produced by 97 and 71% of females using sperm stored in their spermathecae for one and two years, respectively. The remaining ripe females, held isolated from males, either produced egg clutches composed totally of nondividing eggs or never extruded eggs. Some nonovigerous females that had been isolated from males for two years were allowed to mate and subsequently produced viable eggs. Autopsy revealed that these females had both old and fresh sperm in their spermathecae, suggesting that the older sperm were not viable. Females forced to use stored sperm to fertilize three successive annual egg clutches produced only nonviable eggs in the third year.