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Abstract
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Article Information:
The Morphology, Abundance, Size and Sex Distribution of Callinectes amnicola (De Rochebrune, 1883) from Okpoka Creek, Niger Delta, Nigeria
J.F.N. Abowei and A.D.I. George
Corresponding Author: Abowei Jasper
Submitted: 2009 August, 20
Accepted: 2009 September, 02
Published: 2010 January, 05 |
Abstract:
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The morphology, abundance, size and sex distribution of callinentes amnicola from Okpoka Creek
was studied for one year. Callinectes amnicola carapace is broad, moderately convex, ending laterally in a
strong spine, preceded on the lateral margin by 9 distinct teeth. The length of the lateral spine is twice or more
than that of proceeding tooth. The carapace width is about twice or slightly more than tw ice its length
(2.0 – 2.3 times). Carapace upper surface is roughly granular. Epibranchial ridges are without distinct inflection
in middle, almost straight. Four sub-median frontal teeth are well developed and are usually half or more than
half as long as the outer pair. The chelipeds are strong, unequal and pincers with distinct ridges. A s with other
Portunids, the last (fifth) walking leg with propondus and dactylus is broad and flat, paddle-shaped to
accommodate swimming. The crab species exhibit obvious sexual dimorphism. Male blue crabs have a
T-shaped abdomen readily distinguishable from both juvenile and adult stages of the female. Female may be
identified due to their triangular or rounded aprons. Immature females have triangular shaped abdomen with
fused segments. However at the terminal or pubertal molt, the final ecdysis and onset of sexual maturity, the
mature female abdomen becomes broad and rounded. It is also easily identified by its body color, which is
generally described variously as olive-brown molted, and as blue or bluish with pink and pale legs. The highest
number of male crabs was recorded in station 6 (24.50%) followed closely by station 5 (22.66%) then station
2 (15.97%), station 4 (15.76%), station 1 (10.77%) and station 3 (10.33%). Similarly, the females were most
abundant in station 6 (23.90%), followed by station 5 (22.92%), station 4 (21.89%), station 2 (14.81%), station
3 (9.0%) and station 1 (7.47%) the least in abundance. The distributions were similar for both males and
females. The size classes 30 – 39.99mm and 40 – 49.99mm were the highest in number for both sexes. The least
number was recorded for size class 70 – 79.99mm. A total of 13,785 specimens of Callinectes amnicola
comprising 45.5% males and 54.5% females were recorded. The crab’s sizes ranged from 11mm to 74mm
(males) and 12 to 76mm (females). The total weight ranged from 1.79g to 146.72g (males) and 1.17 – 151.62g
(females). The largest size for the males (74mm, 146.72g) and females (76mm, 151.62g) were observed in
December. The smallest size of the male (11mm, 1.79g) and the female (12.0mm, 1.17g) were recorded in
October. The fairly higher body dimensions showed by males and females of C. am nicola in Okpoka is an
indication that the creek is productive and environmentally stable.
Key words: Callinectes amnicola, morphology, abundance, sex and size distribution, Okpoka Creek, Nigeria,
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Cite this Reference:
J.F.N. Abowei and A.D.I. George, . The Morphology, Abundance, Size and Sex Distribution of Callinectes amnicola (De Rochebrune, 1883) from Okpoka Creek, Niger Delta, Nigeria. Current Research Journal of Biological Sciences, (1): Page No: 27-34.
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ISSN (Online): 2041-0778
ISSN (Print): 2041-076X |
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