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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River basin in Wyoming (Simon 1946, Baxter and Simon 1970, Baxter and Stone 1995,
WGFD 2001}.
Water temperatures recorded in roundtail chub habitat range from 0 to 32 °C (Deacon
and Bradley 1972, Bestgen 1985, Bestgen and Propst 1989). In a controlled laboratory
experiment, Schumann (1977) reported critical thermal maxima ofyoung-of--year (YOY}
roundtail chubs to range from 30.5 to 39.5 °C, depending on acclimation temperature,
and critical thermal minima to range from 7.7 to <1 °C, again depending on acclimation
temperature. Fish acclimated at 8, 24, and 30 °C preferred water temperatures ranging
from 20 to 24 °C (Schumann 1977). Schumann (1977) concluded that tolerances to
temperature and oxygen extremes exceeded environmental extremes in the Moapa River.
He further suggested that temperature was not singly limiting distribution of Gila
robusta, but that sub-optimal conditions were likely in many habitats occupied by the
species. It is likely that the species investigated by Schumann was Gila seminuda, a
closely related farm of Gila not taxonomically r~ognized at the time of his research.
Roundtail chubs occupy streams with a variety of substrates (Sigler and Sigler 1996).
Juvenile and adult roundtail chubs in the Gila River Basin were found over fine sand to
boulder-sized substrate, but most oflern occur over sand-gravel (Bestgen 1985, Rinne
' 1992). Alternatively, Barrett and Maughan (1995) found adult mundtail chubs elected

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large boulder and bedrock substrate in Wet Beaver Creek, Arizona. Smaller, young
roundtail chubs generally occupy shallower, lower-velocity (<61 cm/s) water than adults
(Neve 1976, Bestgen 1985, Barrett and Maughaa 1995, Sigler and Sigler 1996). Lanigan
and Berry (1981 }found young roundtail chubs in pools "...where there was some water
movement, such as those below riffles, and pools formed by debris on the margins of the
river." Roundtail chub larvae use low-velocity backwaters (Neve 1976, Haines and Tyus
1990, Ruppert et al. 1993).
Final Report September 2002
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