Flannelmouth sucker (Catostomus latipinnis), bluehead sucker (Catostomus
discobolus), and roundtail chub (Gila robusta), hereafter target species, are native to the
Colorado River basin and have undergone declines in both abundance and distribution
throughout their ranges. Due to these declines, state and federal agencies have entered
into a range-wide conservation agreement and strategy to ensure the persistence of these
species in their native ranges (Utah Division of Wildlife Resources 2006)
Weitzel (2002) reports that these three species were historically abundant in the
Green River watershed of southwestern Wyoming. However, populations have declined
in Wyoming (Weitzel 2002) and throughout the Colorado River drainage (Bezzerides and
Bestgen 2002). The Wyoming Natural Diversity Database assigns bluehead sucker
(BHS) the global ranking of G4 suggesting this species is abundant and globally secure,
although it may be quite rare in portions of its range and should therefore be an object of
long-term concern (Keinath et al. 2003). Flannelmouth sucker (FMS) have been assigned
the global ranking of G3/G4, which suggests its existence is uncertain. It is uncommon
but appears to be locally secure. Roundtail chub (RTC) have been assigned the ranking
of G3, which suggests its existence to be quite rare throughout its range or locally
abundant and highly restricted. Additionally, the Wyoming Game and Fish Department
classifies these three species as NSS1 species, meaning that they are rare and their habitat
is declining or vulnerable.
Baxter and Simon (1970) and Wheeler (1997) represent the only drainage-wide
fish surveys conducted in the Green River watershed of southwest Wyoming. The recent
surveys conducted by Wheeler (1997) show that from 1965 to 1995 the three species
declined in the Wyoming portion of the Green River drainage at three spatial scales (site,
stream, and sub-drainage). In 1995, Wheeler documented BHS in the Hams Fork
drainage, and RTC in the Hams Fork, Blacks Fork and Little Snake River drainages. In
1995, FMS were documented throughout the Green River drainage downstream of
Fontenelle Reservoir and in the Little Snake River drainage (Wheeler 1997). In addition
to these drainage-wide survey efforts, the Bitter Creek sub-drainage was surveyed in
1993 (Carter and Hubert 1995) and the Big Sandy River sub-drainage was surveyed in
the 1960’s and 1970’s (Miller 1978).
