Sardines of Lake Tanganyika Prove One And Indivisible
The sardines from Lake Tanganyika form one homogeneous group, according to a genetic study. This implies that the four countries around the lake will have to team up to maintain the overfished sardines. The fish offers food security to millions of people in Central Africa.
(c) Els De Keyzer
Biologists from Royal Belgian Institute of Natural Sciences, the Royal Museum for Central Africa and KU Leuven found out that local sardines (Stolothrissa tanganicae) form a single genetic group along the seven hundred kilometre-long Lake Tanganyika. There are no subgroups. 'This could indicate that the fish move along the length of the lake,' says fish biologist Maarten Van Steenberge (RBINS and RMCA). 'This also means that overfishing in one zone leads to less sardines elsewhere in the lake'.
There are four countries around the lake: DR Congo, Tanzania, Burundi and Zambia. The sardine is vital for the food security of millions of people in those countries, also because it is the prey of many other food fish in the lake, such as the Lates perches.
Van Steenberge: 'The sardine population in Lake Tanganyika is shrinking. The four countries will have to work together to better manage this fish stock. It will not work if one country manages its share of the lake sustainably, for example by imposing quotas on its fishermen, while the same sardines are collected en masse just across the border'.
Too little knowledge
The researchers sampled sardines at five locations along a north-south axis of the lake in August 2016. From the catches of local fishermen, they selected a total of 96 sardines for genetic study.
'During the fieldwork, local communities showed great interest in helping to protect the fish stocks, but there is a lack of essential knowledge to construct a good management plan', says PhD student Els De Keyzer (KU Leuven), who carried out the study together with Zoë De Corte (JEMU, the joint molecular lab of RBINS and RMCA). This study, published in BMC Evolutionary Biology, is a first step to inform the public and policy makers. Further genetic studies are planned, as well as a survey of how local fishermen feel about different measures of conservation.
The study was supervised by CEBioS, the RBINS’s biodiversity and development cooperation programme.
Scientific article: De Keyzer et al., First genomic study on Lake Tanganyika sprat Stolothrissa tanganicae: a lack of population structure calls for integrated management of this important fisheries target species, BMC Evolutionary Biology, 2019, 19:6. https://doi.org/10.1186/s12862-018-1325-8