9425

• UCREFRP Catalog Number: 9425
• Author: Bezzerides, N. and K. Bestgen.
• Title: Status Review of Roundtail Chub
• USFW Year: 2002.
• Copyright Material: NO

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of the three study species have declined. Roundtail chubs and flannelmouth suckers were
historically common in headwater streams and mainstem rivers throughout the CRB.
Bluehead suckers historically occurred in mainstem and tributary habitats downstream to
the mouth of Grand Canyon.
Roundtail chubs now occupy approximately 45% of their historical range in the CRB
(roughly 30 and 55% of historical lower and upper CRB habitats, respectively}.
Flannelmouth suckers occupy approximately 45% of their historical range in the CRB
(roughly 25 and 50% of historical lower and upper CRB habitats, respectively). Bluehead
suckers occupy approximately 50% of historical CRB habitat (roughly 60 and 45% of
historical lower and upper CRB habitats, respectively}.
We identified 15, 14, and 12 ~pulations of roundtail chub, flannelmouth sucker, and
Bluehead sucker in the CRB, respectively. Population designations are likely to change
with further analyses of abundance, movement patterns, and genetic information,
identification of additional collection localities, repatriation of skies to historical
habitats, and removal of migration barriers.
Like the four federally endangered fish, roundtail chub, flannelmouth sucker, and
Bluehead sucker appear to have declined due to reservoir construction and operation, and
invasion of non-native fish species. However, the study skies have persisted in some
locations where the four endangered, big-river fish did not, in part perhaps because of
adaptive life history traits and use of smaller tributary systems. Several Colorado River
Basin states currently provide protection for the three species, and a conservation plan is
in its formative stages.
Final Report September 2002
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