Functional Maturity in Small Male Snow Crabs (Chionoecetes opilio)

1988 ◽  
Vol 45 (12) ◽  
pp. 2106-2109 ◽  
Author(s):  
G. P. Ennis ◽  
R. G. Hooper ◽  
D. M. Taylor
Keyword(s):  
Rapid Development ◽  
Carapace Width ◽  
Reproductive Potential ◽  
Snow Crab ◽  
Small Male ◽  
Chionoecetes Opilio ◽  
In Captivity ◽  
Breeding Migration ◽  
High Level ◽  
Snow Crabs

The mean size of male snow crabs (Chionoecetes opilio) in sexual pairs during the annual spring breeding migration to shallow water in Bonne Bay, Newfoundland, decreased from 118.6 mm carapace width (CW) in 1983 to 100.3 mm in 1987. This decrease is due to an increase in males <95 mm CW participating from 1.5% in 1983 to 32.3% in 1987. This change appears to have resulted from a reduced abundance of commercial size [Formula: see text] males due to a rapid development of an illegal fishery on this previously unfished population and, as a consequence, less competition between males for possession of females. The percentages of spermathecae containing new spermatophores for females paired with males <95 mm CW (67%) and those with males [Formula: see text] (79%) were not significantly different. We assumed that each female with new spermatophores had recently mated with the male with which it was paired. Observations on selected pairs in captivity showed that males <95 mm CW are capable of mating with both primiparous and muitiparous females. Our results indicate that small mature males can replace large males in breeding activity in a snow crab population. We conclude that in the male-only snow crab fishery in Atlantic Canada with a minimum legal size of 95 mm CW, population reproductive potential is maintained at a high level despite high exploitation rates on males [Formula: see text].

Changes in the Composition of Snow Crab (Chionoecetes opilio) Participating in the Annual Breeding Migration in Bonne Bay, Newfoundland

1990 ◽  
Vol 47 (11) ◽  
pp. 2242-2249 ◽  
Author(s):  
G. P. Ennis ◽  
R. G. Hooper ◽  
D. M. Taylor
Keyword(s):  
Reproductive Potential ◽  
Snow Crab ◽  
Rapid Decline ◽  
Chionoecetes Opilio ◽  
Scuba Divers ◽  
Crab Population ◽  
High Incidence ◽  
Breeding Migration ◽  
High Level ◽  
Snow Crabs

Sexually-paired snow crabs (Chionoecetes opilio) participating in an annual spring breeding migration to shallow water in Bonne Bay, Newfoundland were collected by SCUBA divers from 1984 to 1989. In 1984 the breeding pairs were composed mainly of relatively large, old-shell animals of both sexes, but by 1988 much smaller animals, most of which were new-shell, dominated the migration. Evidence from research fishing indicates that these changes are related to a rapid decline in what was characteristically a virgin population in 1984 and a coinciding strong pulse of recruitment into the breeding component of the population. A very high incidence of small, subcommercial males participating in the 1988 and 1989 breeding migrations demonstrates a capacity for maintaining a high level of reproductive potential in a snow crab population despite high exploitation rates on larger animals in the male-only fishery for this species. The strong recruitment pulse which occurred in Bonne Bay as the virgin population declined after 1984 also indicates a capacity for enhanced annual production within a snow crab population when exploitation rates are high.

Embryo development and reproductive cycle in the snow crab, Chionoecetes opilio (Crustacea: Majidae), in the southern Gulf of St. Lawrence, Canada

1998 ◽  
Vol 76 (11) ◽  
pp. 2040-2048 ◽  
Author(s):  
Mikio Moriyasu ◽  
Carole Lanteigne
Keyword(s):  
Water Temperature ◽  
Embryo Development ◽  
Reproductive Potential ◽  
Snow Crab ◽  
Intermediate Water ◽  
Pigment Formation ◽  
Chionoecetes Opilio ◽  
In Captivity ◽  
Higher Temperature ◽  
Snow Crabs

Embryonic stages and egg-incubation durations were compared between female snow crabs, Chionoecetes opilio, in captivity and from the wild. In the southern Gulf of St. Lawrence the incubation time is 24-27 months. There are two prolonged periods of embryo development: (1) stages 3 and 4 (cleavage and blastula, gastrula) last for at least 6 months between May and January following egg extrusion, and (2) stages 11 and 12 (eye-pigment formation, chromatophore formation) last for 3-4 months between October and January of the following year. Water temperature plays an important role in determining the egg-development rate. Embryo development takes 12-13.5 months (365-410 days) when females are kept at a higher temperature (1.8-3.8°C) than that of the normal habitat (-1 to +1°C). Ovigerous females usually inhabit depths of 40-100 m, which is the cold intermediate water in the southern Gulf of St. Lawrence (year-round temperature and salinity -1 to +1°C and 32-33‰, respectively). However, ovigerous females are also observed at depths of 100-300 m in the Laurentian Channel, where the year-round water temperature is 3-5°C. For ovigerous females that do not migrate to the deeper, warmer waters, the duration of embryo development is 2 years, whereas females that inhabit deeper waters develop their embryos over a 1-year cycle. The reproductive potential and abundance of females with 1- and 2-year embryo-development cycles in the southern Gulf of St. Lawrence are unknown.

Influence de la croissance et de facteurs du milieu sur l'alimentation du crabe des neiges, Chionoecetes opilio (O. Fabricius), dans le sud-ouest du golfe du Saint-Laurent

1991 ◽  
Vol 69 (2) ◽  
pp. 489-494 ◽  
Author(s):  
L. Lefebvre ◽  
J.-C. F. Brêthes
Keyword(s):  
Mineral Content ◽  
Feeding Activity ◽  
Carapace Width ◽  
Stomach Contents ◽  
Snow Crab ◽  
Feeding Preferences ◽  
Chionoecetes Opilio ◽  
Nocturnal Feeding ◽  
Significant Difference ◽  
Snow Crabs

The stomach contents of snow crabs (Chionoecetes opilio) of carapace width >0.6 cm and <7.3 cm were examined in 650 specimens collected at the entrance of the Chaleur Bay, in the southwestern region of the Gulf of St. Lawrence. Individuals were collected with a beam trawl at depths of 70–120 m, on gravelly–muddy and muddy substrates, during the summers of 1986 and 1987. A repletion iridex (RI) was estimated and the daily feeding rhythm of early benthic stages (carapace width <3.0 cm) was determined while considering four classes of RI on 246 crabs. A significant difference between day and night in RI was observed, indicating nocturnal feeding activity in early benthic stages of snow crab, as is the case in the older stages. The mineral content of stomachs, as determined by burning, increases proportionally with the size of the crab. Diet is dominated by crustacea (85% of stomachs), followed by polychaeta (83%) and mollusca (19%). A correspondence analysis conducted on preys and variables (depth, substratum, and size of crab) showed common feeding preferences for crabs of the same size in spite of environmental disparity.

Growth and moulting of wild-born immature snow crabs, Chionoecetes opilio (Fabricius, 1788) (Decapoda, Majoidea), in the laboratory

Crustaceana ◽  
2015 ◽  
Vol 88 (7-8) ◽  
pp. 911-922 ◽  
Author(s):  
Takeo Yamamoto ◽  
Tatsuya Yamada ◽  
Takahiro Kinoshita ◽  
Yuji Ueda ◽  
Hiroshi Fujimoto ◽  
...  
Keyword(s):  
Sea Of Japan ◽  
Probability Model ◽  
Natural Habitat ◽  
Carapace Width ◽  
Laboratory Culture ◽  
The Sea Of Japan ◽  
Growth Indices ◽  
Chionoecetes Opilio ◽  
Model Based ◽  
Snow Crabs

Growth and moulting of wild-born immature snow crabs (Chionoecetes opilio (Fabricius, 1788)) were investigated by laboratory culture experiments. Crabs with 16.2-42.9 mm carapace width caught from the Sea of Japan were cultured at a temperature of their natural habitat (approximately 1°C). The growth indices (size increments at moulting in mm and in % of premoult carapace width) and intermoult period were significantly affected by premoult carapace width, but sex did not affect these variables. Furthermore, we demonstrated that premoult carapace width and days after moulting significantly affected moulting probability and we developed a moulting probability model based on these variables. From this model, the number of days of intermoult periods when moults occurred in 50% of crabs of instars VI, VII and VIII was estimated at 234, 284 and 346 days, respectively.

Neuromuscular analysis of the chela-closer muscle associated with precopulatory clasping in male snow crabs, Chionoecetes opilio

1992 ◽  
Vol 70 (12) ◽  
pp. 2356-2363 ◽  
Author(s):  
C. K. Govind ◽  
A. T. Read ◽  
W. T. Claxton ◽  
R. W. Elner
Keyword(s):  
Carapace Width ◽  
Motor Pattern ◽  
Low Frequency ◽  
Thick Filament ◽  
Thin Filaments ◽  
Chionoecetes Opilio ◽  
Sustained Activity ◽  
Synaptic Potentials ◽  
Slow Fiber ◽  
Snow Crabs

Male snow crabs, Chionoecetes opilio (Majidae), use their modified chelae to retain females for weeks before copulation. Consequently, adaptations for such sustained activity were examined in the chela-closer muscle responsible for clasping. Based on an allometric increase in the ratio of chela size to carapace width, male snow crabs were categorized as morphometrically mature or immature, the former displaying precopulatory clasping more readily than the latter. However, the two types were similar in terms of the properties of the chela-closer muscle, which was examined in this study. The motor pattern during clasping consisted of low-frequency firing of one of the excitor motoneurons, which gives rise to small synaptic potentials. The other excitor motoneuron, which produces large synaptic potentials, fired only when the female struggled during the embrace. The synaptic potentials of both axons showed little if any fatigue at these low firing frequencies. The neuromuscular terminals of these motoneurons displayed areas of synaptic contact larger than most found in other tonically active crustacean muscles. The majority of these synapses had an active site for transmitter release denoted by a dense bar, with many containing more than three dense bars. The closer muscle had typically slow features, with 10 or 11 thin filaments surrounding a thick filament, and sarcomere lengths of 9 – 10 μm. Overall, the closer muscle with its slow-fiber composition, tonic motoneurons, and neuromuscular synapses is well suited to sustained, low-level activity such as precopulatory clasping.

SERUM PROTEIN CONCENTRATION AND SOMATIC INDEX IN RELATION TO MORPHOMETRIC MATURITY FOR MALE SNOW CRAB, CHIONOECETES OPILIO (O. FABRICIUS, 1788), IN THE BAIE DES CHALEURS, CANADA (DECAPODA, BRACHYURA)

Crustaceana ◽  
1999 ◽  
Vol 72 (5) ◽  
pp. 497-506 ◽  
Author(s):  
Michel Comeau ◽  
Marc Lanteigne ◽  
Roland Cormier
Keyword(s):  
Serum Protein ◽  
Protein Concentration ◽  
Mature Male ◽  
Snow Crab ◽  
Juvenile Male ◽  
Chionoecetes Opilio ◽  
Wet Weight ◽  
Snow Crabs ◽  
Somatic Index ◽  
Serum Protein Concentration

AbstractThe serum protein concentrations of juvenile and mature male snow crabs, Chionoecetes opilio, were measured using a refractometer. The somatic indices of juvenile and mature male snow crab were calculated using the weight of the dry flesh of the chelae versus its wet weight. Results indicate that juvenile male snow crab have significantly higher serum protein concentrations and significantly lower somatic indices than their mature counterparts. These observations are attributed to basic physiological differences that could be explained by a terminal moult. Les concentrations en proteines seriques de males juveniles et a maturite du crabe des neiges Chionoecetes opilio ont ete mesurees au moyen d'un refractometre. Les indices somatiques de ces individus ont ete calcules en utilisant le rapport entre le poids sec et le poids humide de la chair. Les resultats indiquent que les individus males juveniles ont des concentrations en proteines seriques significativement plus elevees et des indices somatiques significativement plus bas que les individus males matures. Ces observations sont attribuees a des differences physiologiques de base qui peuvent etre expliquees par une mue terminale.

Lipofuscin Quantification as a Potential Tool for Age Estimation in Snow Crabs,Chionoecetes opilio (O. Fabricius, 1788) (Decapoda, Oregoniidae)

Crustaceana ◽  
2011 ◽  
Vol 84 (12-13) ◽  
pp. 1441-1463 ◽  
Author(s):  
R. N. Allain ◽  
M. Moriyasu ◽  
B. D. Crawford ◽  
S. C. Courtenay
Keyword(s):  
Age Estimation ◽  
Carapace Width ◽  
Cell Mass ◽  
Lipofuscin Granule ◽  
Fluorescent Intensity ◽  
Chionoecetes Opilio ◽  
Density Reduction ◽  
Neuron Density ◽  
Neuron Size ◽  
Snow Crabs

AbstractLipofuscin 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.

Morphometry and Gonad Maturity of Male Snow Crab, Chionoecetes opilio

1992 ◽  
Vol 49 (12) ◽  
pp. 2460-2468 ◽  
Author(s):  
Michel Comeau ◽  
Gérard Y. Conan
Keyword(s):  
Carapace Width ◽  
Immature Stage ◽  
Juvenile Stage ◽  
Snow Crab ◽  
Sexual Character ◽  
Gonad Maturity ◽  
Chionoecetes Opilio ◽  
Juvenile Males ◽  
The Relationship ◽  
Determinant Factor

The relationship between chela height (CH) and carapace width (CW) of male snow crab, Chionoecetes opilio, goes through three allometric stages. The "immature stage" (mostly < 34 mm CW) evolves into a "juvenile stage" (34–120 mm CW) through a "juvenile molt" defining a change in allometry marked by an angular point around 34 mm CW. Fifty percent of males reach gonad maturity, defined by the presence of spermatophores inside the vasa deferentia, at an estimated size of 34 mm CW) The third allometric stage, "morphometrically mature," is separated from the juvenile stage by a "molt to morphometric maturity" at sizes ranging from 50 to 120 mm CW. Juvenile males have smaller claws than morphometrically mature males of the same size. This secondary sexual character is justified by a specific behavior of the males holding the pereipods of the female in one chela during precopulatory embrace. Male snow crab efficiently mate in nature with intermolt multiparous females only after reaching morphometric maturity. Therefore, the presence of spermatophores is not the sole determinant factor necessary for male copulation. Juvenile males larger than the minimum legal size of 95 mm CW are harvestable before, they may efficiently mate.

Hemolymph Ecdysone Concentration as a Function of Sexual Maturity in the Male Snow Crab (Chionoecetes opilio)

1992 ◽  
Vol 49 (8) ◽  
pp. 1619-1623 ◽  
Author(s):  
Roland J. Cormier ◽  
Alan R. Fraser ◽  
Richard F. J. Bailey ◽  
Nicole Raymond
Keyword(s):  
Sexual Maturity ◽  
Carapace Width ◽  
Dry Weight ◽  
Mature Male ◽  
Snow Crab ◽  
Allometric Relationship ◽  
Biochemical Basis ◽  
Chionoecetes Opilio ◽  
Relationship Of ◽  
Juvenile Crab

Ecdysone concentrations in the hemolymph of juvenile and morphometrically mature male snow crab (Chionoecetes opilio) were determined by radioimmunoassay. A logarithmic transformation of the allometric relationship of the dry weight of the chelae versus the carapace width was used to identify morphometric maturity. Results indicate that concentrations of ecdysone found in the hemolymph of juvenile crab are higher than those found in morphometrically mature crab, thus providing a biochemical basis for the observation that the onset of sexual maturity seems to coincide with a terminal molt.

scholarly journals The contribution of fecundity and embryo quality to reproductive potential of eastern Bering Sea snow crab (Chionoecetes opilio)

2016 ◽  
Vol 73 (12) ◽  
pp. 1800-1814 ◽  
Author(s):  
Joel B. Webb ◽  
Laura M. Slater ◽  
Ginny L. Eckert ◽  
Gordon H. Kruse
Keyword(s):  
Bering Sea ◽  
Embryo Quality ◽  
Stock Assessment ◽  
Reproductive Potential ◽  
Large Male ◽  
Reference Points ◽  
Snow Crab ◽  
Eastern Canada ◽  
Chionoecetes Opilio ◽  
Eastern Bering Sea

Development of refined indices of female reproductive potential is needed for estimation of alternative biological reference points for the eastern Bering Sea (EBS) snow crab (Chionoecetes opilio) fishery, which is managed with large male-only harvest regulations. Females were collected from 2007 to 2009 to investigate seasonal and interannual variation in fecundity with maternal size, shell condition (a proxy for age after maturity), and recent mating and again in 2010 to examine biochemical measures (carbon, hydrogen, and nitrogen) of embryo quality. Mean model-adjusted fecundity was highest for primiparous and young multiparous females and declined with advancing shell condition, presumably from senescence. This pattern was also found for clutch fullness indices evaluated from 20 years of stock assessment survey data. Indicators of low female sperm reserves were associated with decreased (∼10%) fecundity for multiparous females. Seasonal comparison of size–fecundity relationships suggested that embryo loss during brooding was minimal, and embryo quality analyses suggested that strong variation with maternal characteristics was unlikely. Finally, fecundity-at-size of EBS females may be lower than that of conspecifics in Japan and eastern Canada.

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