Shell Hardening in Snow Crabs Chionoecetes opilio Tagged in Soft-Shelled Condition

Taylor, David; Marshall, G. W.; O'Keefe, Paul G.

doi:10.1577/1548-8675(1989)009<0504:shiscc>2.3.co;2

Cited by 14 publications

(13 citation statements)

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“…Shell hardening may take between 2 and 3 months post-moult for crabs with a 120-mm carapace (Taylor et al, 1989); this period is even longer for smaller crabs (O'Halloran and O'Dor, 1988). Thus, we expected an increase in hardness over the 5-month period that separated the S 0 and S 2 samples.…”

Section: Discussionmentioning

confidence: 95%

“…1), indicating that shell hardening processes were not completed in the wild even after 150 days. Taylor et al (1989) used evaluation criteria that allowed only for shells to be classified as soft (''Type 1''), hard and new (''Type 2''), or hard and old (''Type 3''), with no degree of variation within the categories. Foyle et al (1989a), using a 7-lb gauge durometer, had set the lower limit to 72 to eliminate soft-shell crabs.…”

Section: Discussionmentioning

confidence: 99%

“…Landed intermoult snow crabs of legal size are able to survive long periods of food deprivation with low rates of mortality and no marked effects on body condition at low temperatures, indicating that snow crabs, like lobsters, could be stored and marketed live year-round (Hardy et al, 1994(Hardy et al, , 2000. Soft-shell snow crabs in the wild require several months to reach the hard-shell condition (Watson, 1971;O'Halloran and O'Dor, 1988;Taylor et al, 1989). The rearing conditions that may promote faster growth rates and would reduce the duration of the post-moult period in legal-sized snow crabs under controlled conditions are unknown.…”

Section: Introductionmentioning

confidence: 99%

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Growth and condition of post-moult male snow crab (Chionoecetes opilio) in the laboratory

Godbout¹,

Dutil²,

Hardy³

et al. 2002

Aquaculture

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We monitored soft-shell and hard-shell legal-sized male snow crabs sampled periodically in the field or fed to satiation at 4.5 jC in the laboratory for changes in nutritional condition. In soft-shell crabs, feeding resulted in a significant decrease of water content in all tissues. This decrease was associated with increased lipid (digestive gland) and protein (muscle and haemolymph) contents. The weight of the muscle in the merus and the weight of the digestive gland also increased. Feeding had no impact on the nutritional condition of hard-shell crabs in the laboratory. In the wild, soft-shell crabs required a much longer period of time to recover to the hard-shell condition than was postulated from earlier studies; nutritional condition of soft-shell crabs did not improve markedly over summer and into autumn. The results of the present study are relevant to aquaculture and stock management. Landed legal-sized hard shell adolescent crabs could be held through terminal moult and grown to a marketable condition in a reasonably short period of time. Nutritional condition indices may also provide valuable information on several aspects of production and contribute to a precautionary management of the snow crab stocks. D

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Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Growth and condition of post-moult male snow crab (Chionoecetes opilio) in the laboratory

Godbout¹,

Dutil²,

Hardy³

et al. 2002

Aquaculture

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“…All age classes of cod return to the eastern portion of the SGSL during the spring (by midMay) (Hanson 1996), increasing the overlap between cod and soft-shell male snow crabs (Chabot et al 2008). Large male snow crabs recover from postmoult (soft-shelled) condition to a hard carapace in 2 to 3 mo (Watson 1971, O'Halloran & O'Dor 1988, Taylor et al 1989, Hébert et al 2002, sometimes longer (Godbout et al 2002). This would indicate that soft-shelled crabs, especially late-moulting individuals, could be available to Atlantic cod for part of their spring/summer migration.…”

Section: Discussionmentioning

confidence: 99%

Top-down interactions and temperature control of snow crab abundance in the northwest Atlantic Ocean

Boudreau

Anderson²,

Worm³

2011

Mar. Ecol. Prog. Ser.

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In much of the northwest Atlantic Ocean, commercially important snow crab Chionoecetes 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.

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“…Maturity status for ran-domly selected male crabs was determined using the formula F = 0.0806 × CW 1.999 , where if F < claw height/10, the crabs were large clawed and if F ≥ claw height/10, then crabs were small clawed (Comeau & Conan 1992). Shell condition was used as a proxy for molt stage and was scored as in Taylor et al (1989), where Shell Condition 1 represented individuals that were soft, having molted within the last few months; Shell Condition 2 represented individuals with hard new shells, having molted within the last year; and Shell Condition 3 represented individuals with hard, old shells, not having molted within 2 yr. Later, an additional category was added as Shell Condition 6, represented by animals with hard, old shells intermediate to Shell Conditions 2 and 3. Crabs with BCD were diagnosed macroscopically by the distinct color change to the carapace of infected crabs (see Fig.…”

Section: Methodsmentioning

confidence: 99%

Epidemiological determinants in outbreaks of bitter crab disease (Hematodinium sp.) in snow crabs Chionoecetes opilio from Conception Bay, Newfoundland, Canada

Shields

Taylor²,

O'Keefe³

et al. 2007

Dis. Aquat. Org.

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Bitter crab disease (BCD) is caused by Hematodinium sp., an endoparasitic dinoflagellate. It lives within the hemocoeloms of snow crabs Chionoecetes opilio and Tanner crabs C. bairdi, making them unmarketable due to their bitter flavor. Two recent outbreaks of BCD have occurred in Conception Bay, Newfoundland, one from 1999 to 2000 and another from 2003 to 2005. In the earlier outbreak, prevalence was highest in juvenile and primiparous females and juvenile males. It was thought to be highest in these hosts because they molt more frequently than larger males and the disease is transmitted to newly molted crabs. In the 2003 to 2005 outbreak, the prevalence of BCD changed and was at its highest, 24% in trapped males and 13.5% in trawled males. This apparent shift in the dynamics of the infection between the earlier 1999 to 2000 and later 2003 to 2005 outbreaks was highly correlated with 2 factors: an increase in bottom temperatures, associated with the recent climatic warming trend in the Northwest Atlantic, and an increase in molting activity of the snow crabs due presumably to the temperature increase within Conception Bay. That is, rising temperatures occurring from 2003 to 2005 likely stimulated molting activity in snow crabs, which led to an increase in susceptible hosts in the population. Given the positive correlation between increased bottom temperature, increased molting activity, and the latest outbreak of BCD, we predict that further trends in climatic warming will enhance transmission, spreading the parasite into additional fishing areas.

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Shell Hardening in Snow Crabs Chionoecetes opilio Tagged in Soft-Shelled Condition

Cited by 14 publications

References 1 publication

Growth and condition of post-moult male snow crab (Chionoecetes opilio) in the laboratory

Growth and condition of post-moult male snow crab (Chionoecetes opilio) in the laboratory

Top-down interactions and temperature control of snow crab abundance in the northwest Atlantic Ocean

Epidemiological determinants in outbreaks of bitter crab disease (Hematodinium sp.) in snow crabs Chionoecetes opilio from Conception Bay, Newfoundland, Canada

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