Classification's Function Relative to Management of Suckers

Suckers are the third most diversified and abundant family group in our freshwaters. Their species numbers, sizes, abundance, and feeding modes contribute to biomass equal to all other native fishes in some ecosystems.  Ecological and management problems with suckers include competition with game fish for benthic insects and zooplankton, potential predation on game fish eggs, loss of genetic diversity by hybridization, and endangered species. Gene exchange creates additional problems for identification and especially classification, the purpose of which should be to enable predictions useful to the study of ecology and management. Runaway gene exchange among species and genera is leading to loss of genetic diversity and species in some western waters. Understanding of the genetics of gene exchange suggests that the lake suckers, Chasmistes (four species of large planktivores), the Lost River Sucker, Deltistes (large, Klamath benthivore), the Razorback Sucker, Xyrauchen (large Colorado River benthivore), and mountain suckers, Pantosteus (12 species of small benthic insect and periphyton feeders) might better be classified as subgenera of common river suckers, Catostomus (17 species of medium-size benthivores). This classification could accurately represent relationships, while keeping introgression within one genus. Readily recognizable morphological traits would enable field and lab identifications, avoid obscure and erroneous molecular classifications, and maintain predictive functions for ecology and management.