9720

• UCREFRP Catalog Number: 9720
• Author: U.S. Fish and Wildlife Service.
• Title: Razorback sucker ‎(Xyrauchen texanus)‎ genetics management and captive propagation plan, Dexter National Fish Hatchery and Technology Center.
• USFW Year: 2004.
• USFW - Doc Type: Dexter National Fish Hatchery and Technology Center
• Copyright Material: NO

(visible implant elastomer) tags on smaller life stages of RBS which will allow early mixing of
family lots, while still enabling identification at a later date. If the implants are retained, this
technique would allow more efficient use of rearing space and mixing of family lots would allow
for the use of culture methodologies that more closely resemble a natural habitat.
"Nature's" rearing is a culture methodology developed in the Pacific Northwest on salmon
hatcheries. This practice advocates that by mimicking the natural environment hatchery fish have
1) reduced hatchery selection for potential fitness related parameters, such as light tank
backgrounds when the stocking environment is dark, and 2) enhanced survival of hatchery reared
fish by imprinting hatchery fish to an appropriate environment. Dexter NFHTC's large earthen
ponds serve as `Nature's rearing habitat for RBS. Before RBS are stocked into ponds, vegetation
is allowed to flourish, and the ponds are fertilized to enrich the plankton food base. Aquatic
insects inhabit the ponds and serve as both food and predators. Bird predation is also present, as
are other predators such as raccoons and turtles. This practice should provide a method of pre-
acclimation for cove or backwater environment where the fish are to be stocked. The sooner fry
can be moved into these rearing environments, the greater the potential for imprinting young fish
to a naturalized environment. VIE tagging would allow the earliest transition possible to the
`Nature's environment.
Non-lethally sampled tissues will be taken from each potential broodfish at Dexter, and
those brought into the facility in the foreseeable future. Tissues will be used for PCR-based DNA
technologies in genetic identification, characterization and monitoring (Amos and Hoelzel 1992;
Ferguson et al. 1995; O'Reilly and Wright 1995). Genetic data will facilitate the management of
broodstock and provide guidance for propagation activities.
The goals for maintaining a ref igia and broodfish population of RBS at Dexter NFHTC
are based on conservation genetic principles as outlined by current conservation genetics theory
(Blouin et al. 1996; Lynch 1996; Ford 2002; Lande 1995; Doyle 2001). Although the statistical
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