Taxonomic and geographic gaps in understanding the functional effects of imperilled fishes on freshwater ecosystems

The effects that fishes have on rates of one or more ecosystem processes (hereafter referred to as functional effects) are often invoked as an important reason for imperilled species conservation. However, the degree to which we understand these effects is rarely evaluated for most groups of fishes. We assessed how well the functional effects of freshwater and diadromous fishes, one of the most imperilled groups of animals, are quantified to date. We found that 88% of studies considering the functional effects of imperilled North American fishes were conducted on one family, Salmonidae. Studies of the functional effects of fishes were also concentrated in Pacific drainages of North America, with few studies in hotspots of imperilled fish diversity such as the Southeastern United States, the arid Southwest and central Mexico. Our results demonstrate the vast taxonomic and geographic gaps in our functional understanding of imperilled fishes and highlight the need to broaden this work to justify the argument that they are functionally important in the ecosystems they inhabit.