Ecological fishing networks in a marine protected area: One possibility for evaluating objectives
The consequences of human actions are a source of changes in ecosystems. These result from alterations in the structure and patterns of interaction of the ecosystem, often with negative consequences in terms of losses of ecosystem function and the extinction of species. As a result, establishing protected areas as Brazil's Extractive Reserves (Resex) is a necessity. Ecological networks can be used as a tool to assess whether the Resex are effective in conserving marine biodiversity and the livelihoods of fishers. By analysing the structure of networks, e.g., their nestedness and modularity, it is possible to understand how species interact with each other, both directly and indirectly. The aim of this study was to analyse and compare the interactions and the management activities affecting fishers and fish at the Canavieiras Resex. The data were collected between April and August 2012 through semi-structured interviews with fishers to identify their target species and the fishing gear that they use to identify the structural patterns of the fish-fisherman, fish-guilds, and functional-group-guilds networks. The target species were Centropomus spp., Lutjanus jocu, Eugerres brasilianus and Mugil spp. Cast nets and trammel nets were the types of fishing gear that were most frequently used. High nestedness and significative modularity patterns were observed in the networks, indicating that generalist and specialist fishers primarily capture their target species. These patterns also indicate the extent of harvesting pressure on these fish. The fishers who use these networks include a high level of fish biodiversity in their catches. The structural pattern that was found implied that fishing pressure on these species, coupled with a lack of management tools, has created a situation in which priority must be given to the development of scientific conservation techniques and sustainable management plans.