Some aspects of the biology of Scylla Serrata (Forskal) - (Crustacea: Portunidae) in Dar es Salaam area

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University of Dar es Salaam
The study of crabs collected from Kunduchi and Mtoni areas has been done. All the crabs collected were identified as scylla serrata {Forskal). More adult males than Females were collected. This has been suggested to be attributed to spawning migration and recruitment rather than effects of fishing gears and methods. Except for abdomen size, growth of skeletal parts and increase in body weight was greater in the males than females. The sizes of the right and left chelae in both males, and females were found not to differ significantly. Sexual maturity was determined from the size of the carapace in both sexes the size of the abdomen width and length in females, estimated for first maturity were 8-12 cm of carapace width, or 4.1-4.7 cm of abdomen width, 5.3-5.9 cm of abdomen length or 2.2-3.0 cm of the first pleopod length in males. Spawning in S. serrata does not occur in the mangrove creeks. The time of departure and rrival in the creeks is regulated by the seasons. September to December (the rainly easons) January to February (the dry seasons) were the peak periods for departureture the creeks and arrival into the creeks respectively. Moulting occurred throughout the study period. The presence of spermatozoa, the gonad maturity stage in but did not appear to occur simultaneously. It is apparent that S. serrata in Dar es Salaam uses different habitatus for spawning and feeding with the creeks being used mainly for feeling and mating. Scylla serrata feed mainly on Mollusca, Crustacea, small crabs and fish.
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Biology, Scylla Serrata
Bashemererwa, V (1981) Some aspects of the biology of Scylla Serrata (Forskal) - (Crustacea: Portunidae) in Dar es Salaam area, masters dissertation, University of Dar es Salaam. Available at (