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4.2 Growth and maturity
P. pelagicus reaches a carapace width CW of 18 cm within 2.5 years in tropical waters. In national fisheries, most crab caught are smaller 9-13 cmIngles Braum 1989. Edgar 1990 describes the
growth of P. pelagicus as extremely rapidly. Crabs sizes increase from approx. 60 mm carapace width after recruitment to approx. 116 mm carapace width within one year.
Table 6: Length-weight growth parameters for P. pelagicus in southern India Abdurahiman et al. 2004.
Length measure Growth parameter
A b
Males Carapace width
3.2-6E 3.616
Carapace length 3.52-4E
3.178 Females
Carapace width 1.63-5E
3.253 Carapace length
8.874-4E 2.930
W=aL
b
, with W = weight g, a = scaling parameter, L = length cm and b = growth exponent P. pelagicus attains maturity at a significantly larger size in tropical waters compared to temperate
regions where growth is slow or absent altogether during winter.
Table 7.Carapace width at 50 maturity CW
50
for P. pelagicus.
Source CW
50
males CW
50
females Comments
Xiao, Y. M. Kumar 2004 -
58.5 ±1.0
mm CW
95
females = 66.3 ±1.9 mm Australian temperate waters
Shields, J.D. F.E.I. Wood 1993
79 - 90 mm 79 - 90 mm Subtropical water of Moreton Bay,
Australia Potter, I.C. S. de Lestang
2000 84 mm
97 mm Australian temperate waters
Ingles, J.A E. Braum 1989 96.4 mm
106.0 mm Philippines
deLestang 2001 96.5 mm
92.4 mm Shark Bay, Australia
deLestang 2001 88.8 mm
87.3 mm Koombana Bay, Australia
deLestang 2001 89.7 mm
86.2 mm Cockburn Sound, Australia
Figure 2.Left: CW
50
determination in male P. pelagicus. Right: cumulative frequency of mature females in per size classes. L
m
represents CW
50
from Ingles Braum 1989.
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Figure 3.Pubertal molt at first maturity
Left: Percentage of those females in each sequential 5 mm carapace width interval which had not undergone a pubertal moult and would thus not have mated and for those which had undergone a
pubertal moult and were therefore of mature size. The logistic curve was fitted to the percentage of crabs that had undergone a pubertal moult in order to determine the CW
50
at first maturity. Right: For males, the logistic curve was fitted to the carapace widths of those crabs which, from the
relationships between the lengths of the propodus of the largest chela and the carapace widths, were capable of mating and were thus adults of mature size. Arrows denote CW
50
for size at maturity of female and male crabs from Potter de Lestang 2000.
4.3 Fecundity
Kategori