The Decline of the Lake Tana (Ethiopia) Fisheries: Causes and Possible Solutions
2017
Dejen, Eshete | Anteneh, Wassie | Vijverberg, Jacobus
This article reviews major findings of a vast body of scientific studies on the ecology of the fish community and the fisheries in Lake Tana over the past 25 years. There are three commercially important fish taxa in the lake: Nile tilapia, African catfish and Labeobarbus spp. The catch per unit of effort for all the three taxa declined during the last two decades: total catch 177 kg/trip in 1993,140 kg/trip in 2001 and 56 kg/trip in 2010. But the most drastic reduction was observed for the Labeobarbus species: 63 kg/trip in 1993, 28 kg/trip in 2001 and only 6 kg/trip in 2010. Most probably, both recruitment overfishing and increased recession farming contributed to the decline. The migrating Labeobarbus spp. were heavily affected by irrigation and dam constructions causing destruction of breeding and nursery habitats in the spawning rivers. We conclude that implementation of the fisheries legislation gazetted in 2003 and the lake management plan adopted in 2015 is crucial to prevent the collapse of the Lake Tana fishery. Suspended silt from erosion and land degradation, caused by deforestation in the catchment, increased the turbidity of the lake water. The current Maximum Sustainable Yield is approximately 10–20 kg ha⁻¹ y⁻¹, which is low compared to other African lakes. The low productivity seems to be caused both by both light limitation and nutrient limitation. Soil erosion is probably limiting primary production. Appropriate land use management and soil conservation around Lake Tana, such as afforestation and implementing zero‐grazing practices, are urgently needed. Copyright © 2017 John Wiley & Sons, Ltd.
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