Trends and environmental drivers of giant catfish catch in the lower Amazon River

Abstract

The giant catfishes Brachyplatystoma rousseauxii, Brachyplatystoma vaillantii and Brachyplatystoma filamentosum are important environmental, social and economic resources in the Amazon. However, anthropogenic environmental changes, such as climate change, deforestation, overexploitation of water resources and damming of rivers, threaten the conservation of this fishery. The aims of this study were to investigate temporal trends and elucidate global and regional environmental drivers of catch for these species of giant catfish in the Amazon. Using annualised catch data (1993–2010), we tested for linear trends using Mann–Kendall tests and built multilinear models of fish catch using effort and a variety of regional and global hydrological and meteorological series. We found a significant decline in the catches of B. rousseauxii and B. filamentosum, whereas the B. vaillantii catch increased. Total catch had a significant positive correlation with fishing effort, and variation in sea surface temperature (SST) explained an additional 19–38% of the variability of catches. Other hydrological and climate variables were weakly correlated or uncorrelated with catch. Overall, these results argue strongly for a resumption the collection of fishing statistics in the Amazon. In addition, associations between SST and catch suggest that conservation of these long-distance migrants must consider both regional and global drivers of fisheries change.