9712

• UCREFRP Catalog Number: 9712
• Author: U.S. Fish and Wildlife Service.
• Title: Genetic characterization of Virgin River chub.
• USFW Year: 2008.
• USFW - Doc Type: Dexter National Fish Hatchery and Technology Center
• Copyright Material: NO

had alleles not found in the other is common in small populations, where rare alleles are
lost as a result of genetic drift. This is typically not considered a problem because the
alleles are not lost to the species, but as different alleles drop out of different populations,
the species retains the same level of genetic diversity overall.
Genetic management recommendations:
In addition to recommending that the captive and wild populations continue to be
genetically monitored in comparison to the baseline developed by this study, the
following management options are suggested:
1. The Moapa River population may need to be treated as a separate management unit
because it is moderately divergent from the Virgin. River populations. Although the level
of genetic variation is lower in the Moapa River population than others surveyed, there is
no indication that inbreeding is present. Therefore, no transfers of chub from other
populations into the Moapa River should be contemplated at this time as they would
unnecessarily expose the population to the risks of outbreeding depression (Edmands
2007). However, because the Moapa River population is distinct and may be at greater
risk than the Virgin River populations, the VRRMRP may want to consider establishing a
separate refuge population to represent the Moapa River.
2. If the VRRMRP determines that the genetic structure found within the Virgin River
has been caused or exacerbated by man-made changes that restrict upstream movement of
chub, the addition of fish ladders or the undertaking of regular transfers of fish from
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