Field Notes
U.S. Fish & Wildlife Service
Field Notes Entry   
Pallid Sturgeon Genetic and Morphometric Differentiation
Midwest Region, July 31, 2005
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Shovelnose sturgeon and the endangered pallid sturgeon co-occur through much of their range. These two similar looking species occasionally hybridize creating a cross that is morphometrically, or visually, different than both parents. It can be difficult for biologists to determine the true ?identity? of hybrid fish. Non-detection of these hybrids can create a severe problem particularly when one fish is endangered. Since pallid sturgeon numbers are currently being boosted with supplemental stocking, it is very important that ?pure? pallid genes are used in propagation. Along with experienced visual identification, precise measurements are taken from the fish in question (head length, barbel length, fin ray counts and others) and these numbers are put into an equation that determines whether or not the fish is a shovelnose, pallid or hybrid. At times this equation, or morphometric index, has been questioned when a fish does not look like the species the index results indicate.

Biologists Wyatt Doyle and Andrew Plauck are working with geneticists Aaron Schrey and Dr. Ed Heist from Southern Illinois University (SIU) to determine a method for distinguishing hybrid sturgeon from the endangered pallid sturgeon. In late 2004, approximately 30 tissue samples were sent to SIU for genetic analysis. Digital photographs of the specimens were then examined to determine the effectiveness of morphometric index in correctly identifying the fish. The comparison showed some disagreement between the morphometric index and the genetic analysis.

This combination of morphometric and genetic identification processes fills the Fish and Wildlife Service's Science and Technology Goal. The use of state-of-the-art genetic techniques to properly identify the endangered pallid sturgeon, will ensure that the Fish and Wildlife Service is doing all that it can to help recovery of the endangered pallid sturgeon.

Contact Info: Larry Dean, 612-713-5312, Larry_Dean@fws.gov
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