African inland fisheries have been observed to sustain high sustainable catches by harvesting a broad spectrum of species and sizes, despite their open-access nature and overall non-selective, mostly unregulated multi-gear fisheries. We use twenty years of multispecies data from experimental fisheries in a fished and an un-fished situation of Lake Kariba to examine whether structural changes in the fish community have occurred. The inshore fisheries on the Zambian side of the lake has had virtually no enforcement of regulations, and experienced high fishing intensity with changing fishing pattern towards increasingly smaller mesh sizes. This resulted in a higher exploitation level, higher yield and reduced stock sizes compared to moderately fished, regulated Zimbabwean side of the Lake, where large sections remained un-fished. Yet, the overall community and sizestructure of the fished situation remained intact, as inferred from (1) directional trends in species composition in the catch and in experimental surveys; (2) recruitment, length and catch rate indicators on a community level as well as main targeted species; and (3) changes in the overall and internal structure of the size spectrum. The Ecosystem Approach to Fisheries calls for an optimum fishing pattern with yield levels that infer the least structural changes on a fish community. As an example, Lake Kariba may indicate that this could be reached by an overall unselective multi-gear fishery.
|Publication status||Published - 2012|
|Event||6th World Fisheries Congress, Sustainable Fisheries in a Changing World, Edinburgh, Scotland - |
Duration: 7 May 2012 → 11 May 2012
|Conference||6th World Fisheries Congress, Sustainable Fisheries in a Changing World, Edinburgh, Scotland|
|Period||7/05/12 → 11/05/12|