Browsing by Author "Tamatamah, Rashid"

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    Comparative Performance of Mixed-Sex and Hormonal-Sex-Reversed Nile Tilapia Oreochromis Niloticus and Hybrids (Oreochromis Niloticus × Oreochromis Urolepis Hornorum) Cultured in Concrete Tanks
    (Springer Link, 2016) Mbiru, Moses; Samwel Mchele Limbu; Chenyambuga, Sebastian W.; Lamtane, Hieromin A.; Tamatamah, Rashid; Madalla, Nazael A.; Mwandya, Augustine W.
    Uncontrolled breeding and precocious maturity in Nile tilapia, Oreochromis niloticus can be avoided by using all-male population. This study compared the growth performance, survival rate, condition factor and final fish tank biomass (yield) of mixed-sex and hormonal-sex-reversed O. niloticus and hybrids (O. niloticus × O. urolepis hornorum) cultured in tanks. Sex-reversed males were produced by feeding newly hatched fry with a diet containing 60 mg of 17α-methyltestosterone for 28 days. Fourteen O. niloticus with initial mean weight (±standard error) of 0.50 ± 0.04, 0.48 ± 0.06 and 0.46 ± 0.01 g for mixed-sex, sex-reversed and hybrids, respectively, were separately stocked in triplicate tanks at a density of two fish m−2 and fed a 300 g kg−1 crude protein diet for 12 weeks. Results showed that hybrids had significantly higher final mean weight (31.41 ± 0.33 g) than hormonal-sex-reversed (25.82 ± 1.51 g) and mixed-sex O. niloticus (19.50 ± 1.26 g; p < 0.05). Similarly, sex-reversed O. niloticus had significantly higher final mean weight than mixed-sex (p < 0.05). The condition factor of hybrids (1.71 ± 0.05) was significantly higher than that of sex-reversed (1.46 ± 0.01; p = 0.001) and mixed-sex O. niloticus (1.43 ± 0.01; p = 0.001). Survival rate was not significantly different among treatments (p = 0.445). The final fish tank biomass was significantly higher in hybrids (535.24 ± 31.67 g tank−1) and hormonal-sex-reversed (486.52 ± 33.70 g tank−1) than mixed-sex O. niloticus (330.05 ± 17.08 g tank−1; p < 0.05). This study demonstrates that hybrids have superior growth performance and condition factor than sex-reversed and mixed-sex but have similar yields to hormonal-sex-reversed O. niloticus. These results suggest that O. niloticus farmers can improve growth rate and yield by rearing hybrids without affecting survival rate.
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    Freshwater Inflows for the Wami River Estuary, Saadani National Park, Tanzania
    (2016-02) Saha, Amartya K.; Kashaigili, Japhet; Mashingia, Fredrick; Kiwango, Halima; Igulu, Mathias; Kimaro, Michael; Hyera, Pendo; Evarist, Roman; Tamatamah, Rashid; Abbott, Vivienne
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    Wild Black-lip Pearl Oyster (Pinctada margaritifera) Spat Collection in Tanzania
    (WIOMSA, 2011) Ishengoma, Edson; Jiddawi, Narriman; Tamatamah, Rashid; Mmochi, Aviti J.
    Abstract—Pearl farming is a growing aquaculture activity in Tanzania but requires sufficient young pearl oysters to make it feasible. Collection of spat in the wild is the most viable way of doing this and was tested to establish whether it would yield sufficient juvenile pearl oysters to support an industry. A total of 4263 Pinctada margaritifera spat were collected over a year at sites considered suitable for spat collection: Bweleo and Nyamanzi on Zanzibar, and Tawalani in Northern Tanzania. Spat “yield” exhibited seasonal variations at these sites in a pattern similar in annual trend at Tawalani and Bweleo but different at Nyamanzi. Generally, the dry season (June-November) yielded a higher number of spat than the wet season (December-May). During the dry season, Tawalani, Bweleo and Nyamanzi produced 877, 942 and 1176 P. margaritifera spat respectively, while, during the wet season, these numbers were 503, 730 and 35. A few other pearl oysters such as Pteria penguin were inadvertently collected at Nyamanzi during the study. Three different types of spat collectors were used during the study, comprising coconut shells, spat bags and rubber tiles. There was significant variation in the number of spat collected on these materials (P < 0.01). The yield was always greater on spat bags and rubber tiles than on coconut shells. The study showed that it is possible to collect sufficient numbers of wild spat for the culture of black-lip pearl oysters at some sites along the coast of Tanzania