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.

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.

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].

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.

Moulting and Mating of Snow Crabs, Chionoecetes opilio (O. Fabricius), in Shallow Waters of the Northwestern Gulf of Saint Lawrence

1992 ◽  
Vol 49 (7) ◽  
pp. 1282-1293 ◽  
Author(s):  
Bernard Sainte-Marie ◽  
François Hazel
Keyword(s):  
Carapace Width ◽  
Male Competition ◽  
Shallow Waters ◽  
Beam Trawl ◽  
Chionoecetes Opilio ◽  
Data Support ◽  
Mean Size ◽  
Males And Females ◽  
Gulf Of Saint Lawrence ◽  
Snow Crabs

Chionoecetes opilio in baie Sainte-Marguerite, Gulf of Saint Lawrence, were sampled by beam trawl in spring from 1988 to 1991 and by divers in March 1991 to document an hypothesized annual moult in shallow waters. Each spring, C. opilio occurred at 4–20 m of depth where 29.3–97.3% of males and 20.3–81.4% of females were moulting or recently moulted. Males and females [Formula: see text] carapace width (CW) moulted only on bottoms < 60 m. Females were mature at [Formula: see text] CW and males were morphometrically mature at [Formula: see text] CW. Overall, 0.3% of morphometrically mature (N = 575) and 23% of morphometrically immature (N = 826) males [Formula: see text] CW, exclusive of soft-shelled, had a visible second carapace. These and other data support the hypothesis of a terminal moult coincident with morphometric maturity. Pubescent females mated with males 59.9–109.3 mm CW (88% were < 95 mm CW), 97% of which were morphometrically mature (N = 120). Mean size of these males was greater than that of males grasping immature females or other males, indicating male competition for pubescent females. Morphometrically mature males were larger on bottoms > 80 m deep, where multiparous females concentrated, than on shallower bottoms.

Depth distribution and seasonal movements of Chionoecetes opilio (Brachyura: Majidae) in Baie Sainte-Marguerite, Gulf of Saint Lawrence

1995 ◽  
Vol 73 (9) ◽  
pp. 1712-1726 ◽  
Author(s):  
Gustavo A. Lovrich ◽  
Bernard Sainte-Marie ◽  
Barry D. Smith
Keyword(s):  
Large Scale ◽  
Depth Distribution ◽  
Carapace Width ◽  
Shallow Waters ◽  
Adult Males ◽  
Chionoecetes Opilio ◽  
Seasonal Movements ◽  
Class Strength ◽  
Gulf Of Saint Lawrence ◽  
Snow Crabs

Bimonthly beam-trawling from April 1991 to May 1992 and diver observations were used to assess distribution and large-scale movement of snow crabs, Chionoecetes opilio, over depths of 4–140 m in a bay of the northern Gulf of Saint Lawrence. Megalopae settled during October 1991. Immature crabs of instars I–IV (i.e., 3.3–9.7 mm mean carapace width, CW) were found predominantly on bottoms ≈50–80 m deep and were cryptic and sedentary. Most immature crabs of instars V–VIII (i.e., 14.1–34.5 mm mean CW) and adolescent males (i.e., producing sperm but not terminally moulted) migrated in winter to subtidal grounds, where they moulted. Movement to shallow waters was massive and resulted in a mean density of 860 crabs per 1000 m2 at ≈15 m in December 1991. Adult males (i.e., producing sperm and terminally moulted) of <70 mm mean CW also moved to the shallow grounds from October to December 1991, where some mated with pubescent–primiparous females (i.e., adult, first brood) from January to April 1992. Adult males of >90 mm mean CW were mainly found at depths >80 m over most of the year, but from March to May 1992 an increase in mean CW of adult males at <80 m indicated some upslope movement, probably to mate with multiparous females (i.e., adult, second or ulterior brood). Adult females were more gregarious and sedentary than adult males. We expand on the hypothesis that interannual variability in recruitment to adulthood tends to reflect differences in year-class strength, and that year-class strength varies in accordance with megalopal supply and (or) survivorship of cryptic instars.

Fecundity and duration of egg incubation for multiparous female snow crabs (Chionoecetes opilio) in the fjord of Bonne Bay, Newfoundland

1999 ◽  
Vol 56 (6) ◽  
pp. 1088-1095 ◽  
Author(s):  
Michel Comeau ◽  
Michel Starr ◽  
Gérard Y Conan ◽  
Guy Robichaud ◽  
Jean-Claude Therriault
Keyword(s):  
Embryonic Development ◽  
Incubation Period ◽  
Reproductive Cycle ◽  
Developmental Stages ◽  
Carapace Width ◽  
Egg Mass ◽  
Chionoecetes Opilio ◽  
Egg Incubation ◽  
Snow Crabs ◽  
Multiparous Female

Multiparous female snow crabs (Chionoecetes opilio) were collected by trap and Nephrops trawl in the fjord of Bonne Bay, Newfoundland, between April 1988 and August 1992 to study the fecundity and embryonic development. A relationship was established between the color of the egg mass and embryonic development. Fecundity was positively correlated with carapace width. A female of 67 mm carapace width can produce up to about 54 000 eggs. Egg mortality over the incubation period could reach 21%, being greater in larger females. Based on the bimodal distributions of embryonic developmental stages observed in the study, the female reproductive cycle was determined as 2 years and females probably only hatch two broods in their lifetime. Eggs hatch mainly in May and June.

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.

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