Spatial variation in environmental drivers on fishery yields in the Amazon river-floodplain

Previous research has suggested that the presence of flooded forests in Amazon River floodplains is associated with higher fish biomass and species richness and is widely recognized as important to the productivity of the fishery. However, flooded forests and other floodplain habitats of the Amazon River are not distributed homogeneously in space, making comparisons between regional fisheries based on habitat relationships difficult. My research aims to: (i) assess spatial trends of fishery catch in relation to floodplain habitat type, (ii) quantify the relationship between floodplain habitat type and multispecies fish catch in the Amazon River fishery, and (iii) quantify the relationship between floodplain habitat type and the catch (probability of being caught and quantity when caught) of commercially valuable species. To address the complexity of a spatially heterogeneous fishery, landing data from monitoring agencies in different regions of the river-floodplain fishery were integrated and associated with floodplain habitat composition using the Hess Wetland Mask (Hess et. al 2015). Generalized Additive Mixed Models (GAMM) were used to describe the non-linear relationship between fish catch, fishing effort, surrounding floodplain habitat cover, and fishing location; seasonal and long-term temporal trends in the data were also considered. The results of my models suggested a gradient of fish catch with the magnitude of fish catch declining from West to East, consistent with patterns of degradation within the environment. My results also supported the positive relationship between multispecies fish catch and presence of surrounding floodplain forests, while species-specific catch varied with habitats related to their feeding habits. Whereas previous research primarily focuses on regional fishing activities of the Upper Amazon, Central Amazon, and Lower Amazon, this research provides a comprehensive assessment of available fisheries data to address basin-wide variation in fish catch. The results of this research emphasize the importance of ecosystem-level management and further demonstrate that floodplain forests are vital habitats for one of the most productive fisheries in the world.