Are Climate Change impacts the cause of reduced fisheries production on the African Great Lakes?
The Lake Tanganyika case study
In the Great Lakes region in Africa, human-induced changes to climatic conditions have allegedly reduced fisheries production. Water temperature in Lake Tanganyika have increased at different rates at different depths. Changes in wind patterns are likely to have caused variations in the intensity and frequency of upwelling. The increased farming activities around the lake have also contributed to accelerated nutrient loading and pesticide and fertilizer run-off. The changes in the lake’s water quality may be a factor that has influenced the output of the fisheries industry. Without taking into account the fishing capacity of the lake's four riparian countries, recent studies on the impacts of climate change and their potential effect indicate that by 2003, the primary and secondary production in the lake would have decreased by 30 percent. However, estimates of the fishing effort and fish harvests appear to contradict the claim that the reduction in harvest is attributed to the rise of water temperature in the lake’s water column. The drop in fish catches and the disappearance of an industrial fleet are not necessarily caused by climate change, but by the sudden upsurge in activities from an expanding artisanal fisheries sector. From 1995 to 2011, the fishing capacity in terms of numbers of fishermen and canoes doubled, whereas the total fish harvest, which was estimated to be around 170 000 tonnes in the 1990s, appears to have decreased to between 110 000 and 120 000 tonnes in 2012. The artisanal fisheries sector, which targets pelagic fish, has outperformed the industrial sector over the years, to the extent that industrial fishing has disappeared completely. The use of illegal fishing gear, such as beach seine and monofilament gillnets, has also contributed to declining fish harvests. In Burundi, strengthened co-management activities have had an immediate effect, with annual production in 2013 increasing by approximately 15 percent over the previous year. It should be noted that that natural variation in recruitment may explain this increase. Further monitoring of the fisheries as well as the limnologicalviii and meteorological conditions may shed more light on the development of fish catches (Van Der Knaap, 2016).