Prediction of Lake Victoria's response to varied fishing regimes using the Atlantis ecosystem model

- Lake Victoria's ecosystem response to various fishing scenarios is described.
- Maintaining current fishing pressure does increase fish biomass and production.
- Not fishing of prey species increases fish production and enhances ecosystem function.

Fisheries management of Lake Victoria has evolved from traditional belief systems of local fishing communities to one with formal national and regional institutions. The impact of management interventions utilized so far is difficult to assess. With the advent of whole ecosystem models, management strategy evaluation has taken root elsewhere. The first such model for Lake Victoria ecosystem has been developed to simulate the chemical, biophysical as well fishing processes. We use the Lake Victoria Atlantis model to simulate the ecosystem under alternative fishing scenarios as compared with the current harvest levels. The effects of the different scenarios are tested using six common ecosystem-level indicators. Predictions show that no particular fishing scenario excels in all the six indicators. However, looking at all the indicators simultaneously, the scenario where halting harvesting of the main prey species (haplochromines) results in the best ecosystem performance, the highest yield of commercially important species and possibly has minimal “socioeconomic” cost implications. Findings of this study reinforce the need for an ecosystem approach to fisheries management in Lake Victoria.