Lake Tanganyika is an old (millions of years), deep, meromictic lake set within the rift valleys of East Africa. An average depth of 570 m and a maximum depth of 1,470 m, make Lake Tanganyika the world’s second deepest lake, after Lake Baikal. Lake Tanganyika supports over 700 cichlid species but four endemic Lates spp. and two endemic clupeids, Limnothrissa miodon and Stolothrissa tanganicae, dominate the open waters (Coulter, 1991; Snoeks, 2000).
Fish are important as a source of food and income across the African Great Lakes. The annual fish catch from Lake Tanganyika is approximately 200,000 tonnes that provides livelihoods for more than 1 million people (Reynolds, 1999). Commercial catches have increased in Lake Tanganyika since the 1970s with a total annual catch in 1995 of 196,570 tonnes (Coenen et al., 1998). Sampling of commercial catches and experimental trawling in Lake Tanganyika has shown that Lates spp. comprise 30% of the catch by weight and clupeids account for 65% (Coenen et al., 1998; Mannini, 1998).
There are more than 800 landing sites around the lake (Mölsä et al., 2002a) and the fishery consists of industrial, artisanal, and traditional fishers. Burundi has the highest CPUE associated with the dominance of S. tanganicae which favors shallow waters making it an easy catch (Mölsä et al., 2002a). Since the late 1960s, the industrial fishery CPUE in Burundi decreased and beginning in the early 1970s, the artisanal (lift net) fishery CPUE increased with the introduction of better equipment (Mölsä et al., 2002a). A similar pattern of CPUE change among the fishery types occurred in Zambian waters (Mölsä et al., 2002a).
Population Growth and the Economy
The human population around the East African Great Lakes has been steadily increasing. Approximately 10 million people inhabit the Lake Tanganyika watershed (UNDP, 2000) with an estimated growth rate of 2–3% per year (World Bank, 1999). Population densities vary by country with the highest density found in Burundi at 250 persons/km2 and the lowest in Zambia at 13 person/km2 (World Bank, 1999).
Settlements in the Lake Tanganyika watershed are small and concentrated on the flatter topography. Subsistence and small-scale commercial fishing and farming provide the primary income (Meadows and Zwick, 2000; Quan, 1996). Per capita income in the four countries sharing Lake Tanganyika (Burundi, DR Congo, Tanzania, and Zambia) ranges from $110−320 US and a large portion of the population lives on less than $1 US per day (UNDP, 2000).