Scaphirhynchus Conference: Alabama, Pallid, and Shovelnose Sturgeon

St. Louis, Missouri, 11-13 January 2005

5.  MORPHOLOGICAL AND ECOLOGICAL VARIATION WITHIN SHOVELNOSE STURGEONS (SCAPHIRHYNCHINAE) OF NORTH AMERICA AND CENTRAL ASIA

Bernard R. Kuhajda*, Department of Biological Sciences, University of Alabama, Box 870345, Tuscaloosa, AL 35487-0345; Phone 205-348-1822; FAX 205-348-6460; bkuhajda@bama.ua.edu

Richard L. Mayden, Department of Biology, Saint Louis University, 3507 Laclede Avenue, St. Louis, MO 63103-2010; Phone 314-977-3494; FAX 314-977-3658; maydenrl@slu.edu

Vladimir B. Salnikov, National Institute of Deserts, Flora and Fauna, 15 Bitarap Turkmenistan Street, 744000 Ashgabat, Turkmenistan; Phone (993-12) 39-04-88; FAX (993-12) 35-37-16; salnikov@ngo-tm.org

Among the most imperiled sturgeon species worldwide are those in the subgenus Scaphirhynchinae, referred to as shovelnose sturgeons.  These sturgeons are found on two continents; three species within the genus Scaphirhynchus in North America and three species within the genus Pseudoscaphirhynchus in central Asia.  Scaphirhynchus species are found in the Mississippi River Basin (including the Missouri River System) and the Mobile Basin, which have been highly modified for navigation, hydroelectric power, and flood control.  Species of Pseudoscaphirhynchus are endemic to the two main river systems in the Aral Sea Basin, where irrigation has caused the complete dewatering of the lower reaches of the Amu Darya and Syr Darya rivers and the devastation of the Aral Sea ecosystem.  Sympatric species of shovelnose sturgeons are found in thousands of river kilometers within the Mississippi River Basin (S. albus and S. platorynchus) and the Amu Darya System (P. kaufmanni and P. hermanni).  Considerable morphological variation has been documented within each of these species, but none of the intraspecific variants, forms, or clines are clearly defined or currently recognized at a taxonomic level, posing potential problems with any successful recovery or conservation efforts.  Hybridization between sympatric species in both genera is also a concern.  Univariate and multivariate analyses of meristic and morphometric characters and evaluation of other morphological features are useful in identifying intraspecific variation.  Tagging and other field studies have shown that different habitats are utilized by these different forms.  Further field studies may reveal that these distinct forms within each species of Scaphirhynchus and Pseudoscaphirhynchus have different life history strategies, varying levels of fishing pressure, and varying abundance.  Recognition and management of these forms as distinct entities is paramount to any meaningful conservation or recovery efforts.