Fisheries ecologists from the University of St Andrews are working with human-health and fishery partners around Lake Victoria on connected, multidisciplinary projects to sustainably manage fish stocks, and to examine the potential role for ‘biocontrol’ by fish of a debilitating human parasitic infection. Both strands of work are contributing directly to multiple United Nations’ Sustainable Development Goals in East Africa.
Under the fisheries strand, Prof. Andrew Brierley and Dr Roland Proud, of the School of Biology, have forged links with the Lake Victoria Fisheries Organisation (LVFO) and with fisheries scientists in each of the three riparian states around Lake Victoria – Uganda, Kenya and Tanzania. They have held fisheries-acoustics training courses and data-analysis workshops in Uganda, St Andrews and Kenya, and are assisting with the application of advanced data analysis techniques to enable recovery of robust time-series of fish biomass estimates from a decade of acoustic survey data. Biomass time-series are required for development of sustainable fishery management plans to underpin regional food security and income: some 35 million people in the Lake Victoria basin depend on fishing, fish and fish products for protein-rich food and for their economic wellbeing. Funding grants supporting this project are for capacity-building in fisheries-acoustics, and for targeted research on an understudied but economically and ecologically important fish species called ‘dagaa’. The work on dagaa will also draw experts from the University of Aberdeen and the Zoological Society of London in to the collaboration network, to contribute expert statistical training and drone survey technology respectively. From a practical perspective, the St Andrews team has also arranged for a professional Scottish fishing skipper to go to Lake Victoria to provide training on the watercolumn fishing that is required to ‘ground truth’ acoustic surveys.
Under the parasitic infection strand, Prof. Brierley has teamed up with the National Institute of Medical Research (NIMR) in Tanzania, the Vine Trust, an Edinburgh-based charity that operates a medical support ship on Lake Victoria, and LVFO. Together the group have won a half-million pound grant from the Royal Society’s Challenge-led scheme for multidisciplinary research towards combatting schistosomiasis. Human populations around Lake Victoria can be heavily infected with the parasitic flatworm that causes schistosomiasis. Schistosomiasis – or bilharzia – is classified as a Neglected Tropical Disease because it is under-researched and does not attract the funding directed at, for example, malaria.
Schistosomiasis is second only to malaria in sub-Saharan Africa in terms of infection. It is a disease of poverty, and is prevalent in communities living in insanitary conditions close to infected waters. Schistosomiasis infects humans when the larval parasites – which emerge from intermediate-host fresh-water snails – burrow through the skin. Infection is high around Lake Victoria, where lake water is used untreated for drinking, washing, cooking and bathing. Humans later excrete parasite eggs, and if sewage returns to the lake in proximity to snails then the parasite lifecycle can be completed. It has been suggested that fishing may have reduced fish that are predators of snails and that, as a consequence, more snails have led to more infection.
In Senegal reintroductions of prawns that are predatory on snails have led to dramatic reductions in human schistosomiasis infection: we will explore the possibility for ‘biocontrol’ by fish of schistosomiasis snails in Lake Victoria. SFC Global Challenges funding has already enabled us to gather fish samples and commence DNA-based analyses of fish stomachs to look for snail presence. With the Royal Society funding, we will conduct shallow water fish surveys and snail counts adjacent to lakeside communities with differing levels of infection. We will also seek to bolster shallow-water fish abundance to reduce snail predation, perhaps by establishing areas closed to fishing. In the marine realm ‘spill over’ of fish from protected areas closed to fishing in to the wider environment leads to improved fish catches outside closed areas. It is possible that in Lake Victoria closing areas to fishing could deliver the win-win result of increased fish for food AND reduced parasitic infection.