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

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United States Department of the Interior
FISH AND WILDLIFE SERVICE
Dexter National Fish Hatchery & Technology Center
P.0 Box 219, 7116 Hatchery Road
Dexter, NM 88230
[phone] [phone] Fax
April 14, 2004
Appendix A.
VVE
LMLAFE
HERVI
Finalization of the document Razorback Sucker (Xyrauchen texanus) Genetics Management
and Captive Propagation Plan, Dexter National Fish Hatchery and Technology Center, and
response to comments received on the draft final version of the Plan.
Hard copies of the draft final plan were mailed to the individuals or agencies listed below on
March 31, 2003, with a 60-day peer review comment period. Five individuals provided verbal or
written comments. The authors have summarized the comments received into three categories
and responded accordingly. We would like to thank all the individuals that responded. Your
assistance greatly improved the quality of the final document.
Comment responses:
The majority of the comments received on the document were editorial and format in nature.
Those applicable were incorporated into the document. A map of the geography of razorback
sucker distribution was added to the document and any missing references from the text and
literature cited section were added.
Several reviewers expressed concern over omission of management strategies that address
enhancing survival of production fish through conditioning. The authors agree that conditioning
fish to flows, and acclimating fish to stocking sites prior to release are essential components of a
stock management program. We, however, do not agree that those strategies should be included
in this genetics management and captive propagation plan. The major focus of this document is
to establish goals, objectives and strategies to effectively maintain razorback sucker captive
stocks and their genetic integrity at Dexter. It is our recommendation that fish conditioning
strategies be addressed in augmentation plans for the species.
The Lake Mohave razorback population is estimated to be fewer than 2,500 individuals with
recruitment of approximately 5% of all stocked fish into the reservoir. In this plan, Dexter has
proposed to establish a captive broodstock of 3,000 adult fish that will be used in a rotational
pedigree breeding program to ensure production fish represent the Lake Mohave razorback
genome. A large captive stock also helps defray the effects of mutational load, drift and selection
over time. Normal attrition of captive reared razorbacks at Dexter is estimated to be 30% over a
23-year period (approximately 1.3% loss annually), based on survival rates of the 1981 year class.
With this in mind a broodstock comprised of 3000 individuals and eight year classes could
potentially contribute to the recovery program for over 75 years.
The broodstock developed will also serve as a captive refugia population and be maintained at
Dexter indefinitely. All broodfish will be rotated into the spawning program and no individual
fish will be spawned twice in 5 years.
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