The sperm plug is a reliable indicator of mating success in female Dungeness crabs (Cancer magster)

2002 ◽  
Author(s):  
S.J. Oh ◽  
D.G. Hankin
Keyword(s):  
Mating Success ◽  
Reliable Indicator ◽  
Dungeness Crabs

Does intense fishing on males impair mating success of female Dungeness crabs

1997 ◽  
Vol 54 (3) ◽  
pp. 655-669 ◽  
Author(s):  
D G Hankin ◽  
T H Butler ◽  
P W Wild ◽  
Q -L Xue
Keyword(s):  
Mating Success ◽  
Egg Production ◽  
Carapace Width ◽  
Minimum Size ◽  
Cancer Magister ◽  
Worst Case ◽  
Mature Adult ◽  
Commercial Harvest ◽  
Size Limits ◽  
Dungeness Crabs

Commercial capture of female Dungeness crabs, Cancer magister, is prohibited and minimum size limits for commercial harvest of male crabs are designed to allow most males to mate at least once before capture. Annual exploitation rates often exceed 90%, however, and the resulting scarcity of large males might reduce mating success among large females. We present new data regarding (i) sizes of male and female crabs collected in premating embraces, (ii) carapace width frequencies of female Dungeness crabs, (iii) presence of sperm plugs and sperm, and (iv) fecundity. Minimum carapace width of hard-shelled mating males typically exceeds postmolt carapace width of soft-shelled females (i), but female Dungeness crabs exceeding the minimum legal size of males usually account for less than 5% of mature adult female crabs (ii), and sublegal-sized males actively participate in mating (i). Remnants of sperm plugs, definitive indicators of mating, were found in 97.5% of recently molted large females (iii), suggesting that virtually all molting females mate regardless of size. On the basis of (ii) and (iv), hypothetical worst-case calculations, assuming that no large females could find mates, suggest that total egg production would be reduced by no more than 2-25% among molting female crabs.

scholarly journals Injury in trapped Dungeness crabs (Cancer magister)

2007 ◽  
Vol 64 (3) ◽  
pp. 464-472 ◽  
Author(s):  
Julie S. Barber ◽  
J. Stanley Cobb
Keyword(s):  
Laboratory Experiment ◽  
Mating Success ◽  
Injury Rate ◽  
Size Ratio ◽  
Crab Species ◽  
Target Species ◽  
Cancer Magister ◽  
Injury Rates ◽  
Crab Density ◽  
Dungeness Crabs

Abstract Barber J. S., and Cobb, J. S. 2007. Injury in trapped Dungeness crabs (Cancer magister). – ICES Journal of Marine Science, 64: 464–472. Although traps are the most effective fishing equipment used to capture crabs they can also result in indirect damage to target species. We examined the effect of trap-soak time, crab density, and the legal to sublegal size ratio on injury rates to male Dungeness crabs, Cancer magister. Our field results show that injuries increase significantly with increased trap-soak time, and as a consequence of different size ratios (crabs in traps with a greater ratio of sublegal crabs had more injuries). The injury rate was independent of density. In a laboratory experiment, injured crabs were as capable as intact crabs of obtaining, defending, and consuming food. However, studies on other crab species indicate that injury reduces growth, delays reproduction, decreases mating success, and increases mortality. If the costs of injury are similar for Dungeness crabs, this could diminish the rate of recruitment into the fishery.

Classification of small type B/C follicles as primordial follicles in mature rats

Reproduction ◽  
2000 ◽  
pp. 43-48 ◽  
Author(s):  
S Meredith ◽  
G Dudenhoeffer ◽  
K Jackson
Keyword(s):  
Dna Synthesis ◽  
Granulosa Cells ◽  
Single Layer ◽  
Reliable Indicator ◽  
Type B ◽  
Primordial Follicles ◽  
Type C

In the present study, follicles were classified according to the morphology of their granulosa cells. Type B follicles contained only flattened granulosa cells; type B/C follicles had a mixture of flattened and cuboidal granulosa cells in a single layer, and type C follicles had a single layer of cuboidal granulosa cells. The primary objectives of the study were to determine whether 5-bromo-2-deoxyuridine incorporation into type B/C follicles was a marker for initiation of growth and how long type B/C follicles could remain at the same stage before transformation to type C follicles. Female Holtzman rats received bromo-deoxyuridine for 7 days. After the infusion (day minipumps were removed = day 0), rats were ovariectomized on days 0 (n = 9), 30 (n = 8), 90 (n = 8) and 150 (n = 9). The numbers of type B, B/C and C follicles within one ovary were determined using modified fractionator counting. Analysis over all times demonstrated that there were more (P < 0.0001) type B/C (941 +/- 61 per ovary) than type C (140 +/- 18 per ovary) or type B (159 +/- 19 per ovary) follicles. The numbers of type B and type C follicles did not differ from each other at any time. Only one of 34 rats evaluated had bromo-deoxyuridine-labelled type B follicles. On day 150, 57% of the bromo-deoxyuridine-labelled type B/C follicles remained from day 0. It is concluded that (1) DNA synthesis in granulosa cells of type B/C follicles is not a reliable indicator of impending growth; and (2) type B and type B/C follicles are both components of the pool of primordial follicles.

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