Lake Tana, Ethiopia's largest lake, has a remarkable and conservation-worthy assemblage of fish species, requiring fisheries management for sustainable exploitation. However, due to anthropogenic impacts, many of these fish species are threatened. Hence, an improved management of these resources is recommended. To allow a more sustainable exploitation of natural resources, a better understanding of the cause-effect relationships between anthropogenic impacts and environmental components is fundamental. The Drivers-Pressure-State-Impact-Responses (DPSIR) framework is a useful tool to describe these links in a meaningful way to managers and policy makers. Despite its potential, application of DPSIR is virtually lacking in developing countries. This paper assessed the potential of the DPSIR framework and used it to comprehensively describe the available knowledge and management needs in the lake catchment. Rapid population growth and the economic transformation are the main driving forces leading to various pressures such as water quality and wetlands degradation as well as declining fish community, which is detrimental to the socio-economic state and health of the local inhabitants. As feedback to the driving forces, pressures, state changes and impacts, optimal multi-level responses are developed. This study aims at providing policy makers a better understanding of the lake catchment in order to bridge the gap between science and decision-making.

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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This study aims at investigating the spawning migration of the endemic Labeobarbus species and C. gariepinus from Lake Tana, through Ribb River, to Welala and Shesher wetlands. The study was conducted during peak spawning months (July to October, 2010). Fish were collected through overnight gillnet settings. A total of 1725 specimens of the genus Labeobarbus (13 species) and 506 specimens of C. gariepinus were collected. Six species of Labeobarbus formed prespawning aggregation at Ribb River mouth. However, no Labeobarbus species was found to spawn in the two wetlands. More than 90% of the catch in Welala and Shesher wetlands was contributed by C. gariepinus. This implies that these wetlands are ideal spawning and nursery habitats for C. gariepinus but not for the endemic Labeobarbus species. Except L. intermedius, all the six Labeobarbus species (aggregated at Ribb River mouth) and C. gariepinus (spawning at Shesher and Welala wetlands) were temporally segregated.

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