Systematic Studies of Southeastern Fishes

Science Center Objects

The southeastern United States is home to a variety of freshwater snails, mussels, crayfish, and fishes. USGS scientists are conducting systematic studies to better document the region's biodiversity.

Etheostoma brevirostrum Group


The Science Issue and Relevance: Conservation scientists have repeatedly stated the need for ongoing systematic studies to document the Earth’s faunal and floral biodiversity. This call for biological knowledge has become part of an international initiative, suggested by E. O. Wilson and headed by the Smithsonian, to create an Encyclopedia of Life (EOL). The EOL goal is to document all life on Earth. This need is exigent for natural resource managers to have accurate knowledge of the true biodiversity in the areas they manage, specifically the numbers of species, subspecies, and distinct populations. The southeastern United States has the richest regional representation of freshwater snails, mussels, crayfishes, and fishes in North America. Description of new species represents an essential contribution to the cataloguing and tracking of our national resources. New species of freshwater fishes are described every year from North America. From 1970 to 2010, the mean rate of species descriptions was 6.7 new species described per year. During that interval, 268 freshwater fishes were described from North America, of which 54% were from the United States, and 129 (48% of the total) were from the southeastern United States.

Methodology for Addressing the Issue: Advances in molecular biology, especially in sequencing DNA, mitochondrial (mDNA) and more recently nuclear (nDNA), has led to significant advances in the documentation of biodiversity and elucidation of phylogenetic relationships. However, field expertise and knowledge of organisms are fundamental skill sets in systematic biology. Studies contributing to significant advancements in systematics of fishes (and other organisms) often incorporate molecular and morphological data, and may include behavioral and ecological data as well. Advances in statistical methods and computer software enable analysis of large datasets that would have been overwhelming endeavors a few decades ago. The anatomical landmarks in the above illustration are an example of a biometric technique used to compare body shapes between fishes.

Future Needs: An expanding human population is transforming our national landscape at unprecedented rates. A prevailing concern among scientists is that modern rates of extinction are orders of magnitude greater than background rates evidenced in the fossil record. Consequently, there is an exigent need for systematic studies and ongoing surveys of aquatic faunas to ascertain the actual levels of biodiversity. Knowledge of the true species richness would likely change current management practices, including natural areas receiving special protection. For example, the U.S. Fish and Wildlife Service are currently investigating the possibility of creating the first wildlife refuge based on a southern Appalachian watershed, the Conasauga River in north Georgia. Future diversity is more likely to be cryptic, that is, superficially similar to known species, have small range sizes (species with large ranges are more readily discovered), and more vulnerable to decline (because of limited occurrence). There is a silent race between scientists endeavoring to document existing diversity and diminution of natural resources from human population growth. Based on current rates of species descriptions (from 1970 to 2010), there may be more than 1450 freshwater fish species documented from North America by 2050.

Products (Data compiled in 2012):

  1. List of Extinct North American Fishes
  2. List of Fishes Deleted from Extinct List
  3. Names of North American Ecoregions
  4. Extinct Fishes by Ecoregion
  5. Ecoregions with Extinct Fishes
  6. Extinct Fishes by Province or State
  7. Provinces & States with Extinct Fishes
  8. Data Summary - Extinct North American Freshwater Fishes