Constellation, le dépôt institutionnel de l'Université du Québec à Chicoutimi

Résumé

Floodplains comprise a complex mosaic of seasonally-flooded forests, lakes and channels that support productive fisheries. These habitats and their fish populations are increasingly threatened by a variety of human pressures, including floodplain deforestation. However, the effects of multiple human pressures on these floodplain fisheries have not been studied in the Amazon River. Here, we investigated the combined effects of forest cover, river water level, fishing effort and distance from nearest urban center on the catch of the most exploited fish taxa. Our study integrated fisheries, hydrological, geographical, and satellite land cover change data for 21 floodplain lake systems over a ten-year period. We found that an ANCOVA model explained 91% of the variation in catch (p < 0.001) and, as usual, fishing effort was the most influential variable. Floodplain forest exerted a positive effect on fish catch, implying that a loss of 1 km2 of floodplain forest induces up to 9% decreasing in fish catches. In addition, high river water level and distance from urban centers also had a positive effect on fish catches; even though, low river water levels did not present such effect. These results provide support to previous findings regarding the effects of habitat, hydrological, and human variables on floodplain fish catch. More importantly, these results provide the first ever quantitative evidence of the effect of floodplain deforestation on fish catch. Our findings point out the need to develop an ecosystemical approach to manage floodplain fisheries in the Amazon and elsewhere in the world.