9384

• UCREFRP Catalog Number: 9384
• Author: Valdez, R. A. and R. J. Ryel.
• Title: Summary of Recovery Goals for the Four Endangered Fishes of the Colorado River Basin.
• USFW Year: 2000.
• USFW - Doc Type: Logan.
• Copyright Material: NO

Razorback Sucker - 4

Delisting Criteria
Delisting of razorback sucker will be considered when the following criteria are met:

Lake Mohave
1. Maintain at least 50,000 adults for genetic viability for at least 15 years as wild
genetic refugia,

Green River Subbasin
1. A minimum estimated population of 5,800 adults for a period of 15 years, such
that:
a. the lower 95% confidence interval of the estimated population of adults
exceeds 5,800,
b. a trend in adult population point estimates for the same 15-year period that
does not decline significantly, and
c. a proportion of age 3 fish for each year that is not significantly higher than
30% or lower than 20% of the adult population for the same I5-year
period.
2. Provide legal assurance and/or agreements for flows necessary to recover the
razorback sucker, including tributaries necessary to life history of the species; i.e.,
Yampa, White, Duchesne, and Price rivers.
3. Procure and protect habitats necessary to recover the razorback sucker, including
flooded bottomlands.
4. Implement successful activities to expand the range of the population of the Green
River subbasin and enhance recruitment; i.e., maintain unimpeded fish pass~ge
within occupied habitats, minimize entrainment in the Green River Canal.
5. Continue nonnative fish control, as needed, to recover the razorback sucker.
6. Take reasonable actions to reduce negative effects of selenium if it is determined
that selenium has significant negative effect on reproductive success and survival
of razorback sucker.

Upper Colorado River Subbasin
1. A minimum estimated population of 5,800 adults for a period of 15 years, such
that:
a. the lower 95% confidence interval of the estimated population of adults
exceeds 5,800,
b. a trend in adult population point estimates for the same 15 year period that
does not decline significantly, and
c. a proportion of age 3 fish for each year that is not significantly higher than
30% or lower than 20% of the adult population for the same 15-year
period.
2. Provide legal assurance and/or agreements for flows necessary for the recover the
razorback sucker, including tributaries which are important to the life history of
the species; i.e., Gunnison River.
3. Procure and protect habitats necessary to recover the razorback sucker, including

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