9411

• UCREFRP Catalog Number: 9411
• Author: Williamson, J. H., D. C. Morizot and G. J. Carmichael.
• Title: Biochemical Genetics of Endangered Colorado Pikeminoow from the Green, Yampa, Colorado, and San Juan Rivers.
• USFW Year: 1998.
• USFW - Doc Type: \
• Copyright Material: NO

1

1
1

1

H
1

1
11
4
Executive Summary
The Colorado pikeminnow Ptvchocheilus lucius is indigenous within the Colorado River basin of
the southwestern United States. It is a large river cyprinid and was listed as endangered by the U. S. Fish
and Wildlife Service in 1967 (U. S. Office of the Federal Register, 32;43[1967]:40001). Declines in fish
numbers and range have been associated with habitat fragmentation and blocked passage, water diversions,
lost spawning and nursery habitat, dewatering, contaminants, and normative fishes introductions.
Our objectives included determinations of whether or not there is genetic differentiation within the
species and genetic relationships among purported populations. This included measuring the amount and
pattern of genetic variation within and among populations. The hypotheses that we tested were: Ho: Color-
ado pikeminnow are genetically homogeneous or panmictic; and Ha: genetically differentiated populations
of Colorado pikeminnow exist. Specific items to be addressed include: 1) Genetic identification and
characterization of the species; 2) Genetic profiles to define management units; 3) Determination of genetic
status of management units; 4) Identification of genetic markers for management purposes; 5) Generation
of genetic data required to develop breeding strategies and broodfish populations and; 6) Production of a
management document with recommendations.
Samples from throughout the presently recognized range of Colorado pikeminnow were obtained
from the upper mainstem Colorado River, Yampa River, Green River, and San Juan River. Hatchery
broodfish populations were sampled from Dexter National Fish Hatchery and Technology Center.
Populations and sampling locations were selected by biologists for the Upper Colorado River Recovery
Implementation Program as locales where adult, juvenile, and young-of-the-year Colorado pikeminnow
potentially could be collected in association with spawning. The products of > 89 allozyme loci were
resolved and assessed for electrophoretic polymorphism. The number of loci is somewhat uncertain
because several of the loci included have not been studied extensively in cyprinids. Alternatively, a
polymerase chain reaction (PCR)-based analysis of potential Mendelian polymorphisms from anonymous
single copy nuclear DNA was conducted on Colorado pikeminnow from the Dexter National Fish Hatchery
and Technology Center (1974 and 1981 broodfish populations), the Green and the Yampa Rivers.
We conclude that the null hypothesis (Ho:) tested, Colorado pikeminnow are genetically
homogeneous or panmictic, is supported herein: 1) We identified genetic components and characterized the
species as presented in Tables 1-6 and the Appendices; 2) We defined genetic profiles for the proposed
management units of the Colorado River and the Green River (including the Yampa River). If
reintroduction of Colorado pikeminnow into the San Juan River is indicated, it should be managed using
fish from the Colorado River or Green River, produced from controlled breeding programs [the combined
Colorado/Green River DX-F1 (81) broodfish population held at Dexter National Fish Hatchery and
Technology Center is not representative of the Green River or Colorado River and should not be used for
stocking the San Juan River]; 3) We identified the genetic status of management units as they are
genetically similar, with no useful genetic markers present and the San Juan River is relatively (genetically)
depauperate. Only rare alleles potentially differentiate the management units; 4) We were unable to
identify genetic markers for management purposes. No such markers exist within our nuclear DNA or
biochemical genetics data sets; 5) We generated genetic data required to develop breeding strategies and
broodfish populations. We recommend that the Colorado/Green 1981 population be replaced with separate
Green River and Colorado River broodfish populations for upper basin recovery efforts. We recommend
that strict and stringent pedigree breeding strategies and genetic management programs are developed and
records be maintained of hatchery and management actions and; 6) we produced this document to serve as
a management guide.
Future studies with larger and more comprehensive analyses of allele frequencies by
subpopulations may lead to revision of these results, but for the present, geographic variability in allele
frequencies suggests that the Colorado pikeminnow be managed for populations in the Colorado River and