Abstract
A study was conducted to determine fish yields from flood depended ponds in Rufiji floodplain, Tanzania. Eight ponds were constructed during dry season in two sites besides two floodplain lakes, Ruwe and Uba. These ponds were selfstocked with different fish species from the lakes. More than eight species were trapped and Oreochromis urolepis, Labeo congoro and Clarias species were considered as good candidates for aquaculture. Other small fish species were harvested immediately after flood recession and the three key species were cultured for the maximum of seven months. However, other species in small quantities were remained in the ponds for the whole period of experiment. Water quality parameters were monitored throughout the study period. The relationships between water quality variables and flooding events were determined using canonical correspondence analysis (CCA). Other parameters included in the relationships were fish density, manure and number of species trapped and cultured. Dissolved oxygen and pH decreased with time in both sites. Fish yields were influenced by some water quality, flooding episode and other management variables. Chlorophyll-a was the only environmental variable that showed a significant correlation with fish yield (P< 0.01). Fish density and number of species trapped showed a significant effect on the fish yield (P<0.05). Re-connectivity between ponds and lakes was strongly positively correlated with yield. It can be concluded that some water quality variables, flooding and management parameters were responsible for the observed yield.
Highlights
Aquaculture in east Africa contributes significantly in food security and income for poor communities
Chlorophyll-a was the only environmental variable that showed a significant correlation with fish yield (P< 0.01)
The first yield canonical correlation accounts for 58% of variance
Summary
Aquaculture in east Africa contributes significantly in food security and income for poor communities. Aquaculture research on mixed fish species from selfstocked ponds in floodplains in east Africa is limited. Kagwa et al (2010) conducted a study on nitrogen cycling and fish productivity in earthen ponds stocked with different fish species in Lake Victoria wetlands. There is need of conducting research on the aquaculture of indigenous fish species. Unlike East Africa, studies on aquaculture of polyculture and small indigenous fish species have been emphasized and conducted extensively in some Asian countries (for example, Alim et al, 2004; Alim et al, 2005; Kadir et al, 2007; Milstein et al, 2008; Rose et al, 2008; Mikolasek et al, 2010)
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