Lake Tanganyika, in Africa, is known as being the longest in the world, a famous biodiversity hotspot, case study for evolutionary, ecological and behavioural processes. It spreads across four countries – Zambia being one of them, in its southwestern portion.

The Zambian portion of the lake was the study area for this project: 2,000 km² of extension, a shoreline of 238 km and 83 fishing villages housing 8,430 fishers and 2,300 vessels. Fishery in the lake is the supporting economic activity for 20,000 people living in these rural areas.

While large scale fish farming is a growing economic activity in the lake, making Zambia the 6th larger producer of farmed fish in Africa and the biggest tilapia producer in the South African Development Community (SADC), it is not accessible to most of the rural population. Hence, the Government has decided to kick-start a programme to encourage and support rural communities to start small cage fish farming family projects on the lake. This is a form of aquaculture where fish are reared inside net enclosures suspended in existing water bodies, requiring low management, low capital input, using family labour and carried mainly for subsistence purposes.

The Government programme’s phase 1 concerns the installation of 10 pilot small-size floating cages for tilapia and the training for extension officers and farmers on tilapia cage farming, processing, and marketing (10 trainees/pilot installation). A future phase 2 of the programme shall include the extension of the “pilot” to 100 small scale cage fish farms.

Nemus’ task was to identify and assess the environmental and socioeconomic effects of aquaculture in the Zambian part of Lake Tanganyika, ensuring that future decision making for the location and extension of the programme is well-planned and leads to strategic and sustainable options.

Besides field work to get to know and assess the whole area and the aquaculture facilities in the region, the project also included a stakeholder’s workshop at Mpulungu, followed by focus group discussions in selected communities.

The project has also included a multi/layer carrying capacity analysis by Nemus, to assist the Government in choosing the best locations for the future small cage fish farms. Issues taken into account to draw the final 5-classes suitability map included: ecological conditioners (protected areas such as National Parks and breeding areas, key biodiversity areas, fish breeding sites and wild fauna ecological relevance), physical-chemical conditioners (distance to shore pollution sources, shoreline configuration), operative conditioners (adequate depth for securing the cages).

Global assessment of all the key issues confirmed that the small-scale cage fish farming programme is relevant for the communities along the Zambian portion of Lake Tanganyika, representing an important contribution to food security and poverty reduction, while increasing resilience against overexploitation of the lake and its shoreline, the spread of some diseases and other external risks like climate change.

This work was Nemus’ first project in Zambia and was developed jointly with the company’s Mozambican subsidiary, Nemus África.