North American Sucker Fish Diets in the Face of Ecological Challenges (Catostomidae)

Basic biological information, like fecundity, age at maturity, habitat occupation and range size, are critically important for conserving species under threat. However, funding for this sort of research is limited, especially for aquatic vertebrates like fishes, which have restricted ranges and are under threat from changes in land-use and watershed alteration. The suckers (Family Catostomidae) are freshwater fishes native to North America (and one species from China). Most species are presumed to be detritivorous, that is, feed on decaying plant and animal matter; however, the diet diversity of this family has never been analyzed at an evolutionary scale. Suckers are under considerable threat from water diversion (e.g., dams and channelization), habitat degradation, and agricultural pollution. Currently, 2.5% of sucker species in the US are recently extinct, and 22% are endangered or vulnerable. We performed a literature meta-analysis to examine the diversity of sucker diets as well as highlight any species which are priorities for conservation. Our specific questions were: (1) What do catostomids eat? (2) Do catostomid species overlap in their resource use? And finally, (3) do evolutionary relationships among species predict diet? We found that suckers consume a wide variety of prey, from insects and fish eggs, to detritus and even seeds. Diet data exists for only 42% of species; therefore, the vast majority of sucker diet diversity is unknown. The few species with unique diets (e.g., Deltistes luxatus, Erimyzon oblongus) tended towards carnivory and are classified as endangered or vulnerable (according to the IUCN and EPA).