Fishing down the value chain: Biodiversity and access regimes in freshwater fisheries - the case of Malawi

This paper considers the connection between the diversity of catch in a multi-species fishery and the productivity of the fishery under different access regimes. A modified Gordon-Schaefer model is used to analyse the importance of the level of diversity in a fishery in open access and profit maximising regimes. The modified model, which includes both environmental and bioeconomic variables, is fitted to data from a gillnet fishery in Lake Malawi. Pressure on stocks is shown to be greater at all levels of biodiversity in open access than it is in profit maximising regimes. However, in a profit maximising regime both catch and the productivity of fishing effort is highest when there is a single marketed species. By contrast, in an open access regime catches are maximised at higher levels of bioeconomic diversity than in profit maximising regimes. Implications for policy are discussed.