Abstract
Fish communities of the Peace River were assessed by standardized boat electrofishing during 2005 – 2006 and compared to historic sampling that occurred during 1983 – 1992. Four non-native species Pterygoplichthys multiradiatus, P. disjunctivus, Hoplosternum littorale, and Hemichromis letourneuxi became established since 1991, and Pterygoplichthys spp. was the most numerically-abundant species in 2006. Abundance and biomass of two non-native species that were established during the historic period, Oreochromis aureus and Clarias batrachus, decreased. Extirpation of native species since the historic period was not documented. Species richness and diversity between the historic and recent periods were stable, but changes in fish community structure as determined from multivariate analysis were apparent. Extreme flooding and three months of hypoxia following three major hurricanes in 2004 greatly affected species composition, but evidence that the community had substantially recovered by 2006 may indicate ecological resilience. These baseline assessments and continued sampling may be useful to document biological changes due to environmental degradation and restoration projects, evaluating minimum flows and levels, understanding short- and long-term impacts of major hurricanes and droughts, and documenting ecological impacts of non-native fishes.