Non-native fish species as an important part of Zambia's food system: a case study of the Lake Kariba fishery

Fish have an important role in food systems of Zambia and are a cheaper source of animal protein, vitamins and minerals. Presently, fish catches are dwindling and many children and women in rural Zambia are malnourished because their diet consists mainly of maize, vegetables and legumes. The main component of the diet is nsima, a form of thick porridge prepared from maize flour, which provides energy as carbohydrates. This study was done to assess the impact of a non-native fish species (Oreochromis niloticus, Nile tilapia) which has both positive and negative impacts on Zambia’s food system, with particular reference to the Lake Kariba fishery. The study was based on a networked systems framework, achieved through the administration of questionnaires, interviewing 377 randomly selected respondents from the three areas of the lake (I, II and IV) and 156 respondents from 7 selected open fish markets. Focus group discussions (FGD) were done with women, men and youth, who were key informants. Analysis of results using chi-square analysis, which cross-tabulated variables were used to obtain the results. Non-native fish were introduced in the early 1980s for cage culture production in Lake Kariba but some fish accidentally escaped. This has changed the composition and abundance of fish species in the lake. Despite the negative ecological impact on native biodiversity, results showed that more fish are available to households, improving nutrition and disposable income from fish sales. The disposable income is used to purchase other foods, thereby reducing malnutrition among rural households. Thus, the introduction of appropriate non-native species might benefit households and the nation as a whole. Key words: Malnutrition, non-native fish species, Lake Kariba, Zambia, tilapia, Oreochromis niloticus