8165

• UCREFRP Catalog Number: 8165
• Author: Czapla, T. E.
• Title: Genetics Management Plan ‎(Revised)‎.
• USFW Year: 1999.
• USFW - Doc Type: Denver, Colorado.
• Copyright Material: NO

Table 2. Status and trends of endangered fish stocks in the Upper Colorado River Basin (X=Known; U=, little or no information; ?=Undetermined, inconclusive or unagreed upon results
based on information available).
Criteria'
Spaces Populations Identified spawning stocks Recruitment Population Estimate Interim Management Status Probability of
(Citation) Objective immediate extinction
Razorback sucker Middle Green River (Yampa XZ X 500 5316 Detaining High
and Middle Green rivers) (Modde, et al. 1993) (t 804)
Lower Green River U U U 5316 Declining High
(± 804)
Upper Colorado River U U U 5316 Decining High
(t 804)
Bonytail3 Upper basin ? ? 7 4118 Nearly High
(±817) extirpated
Humpbadk chub Yampa River X X 600 4796 InsuffiGent Unknown
(Karp and Tyus 1990) (11317) information
Desolation-Gray Canyons X X U 4796 Insufficient Unknown
Black Rocks Canyon
Westwater Canyon
(11317) information
1528 4796 Stable Low
(Pfeifer, et al. 1998) (±1317)
1050 4796 Stable Low
(Chart and Lentsch 1999) (±1317)
Cataract Canyon X X U 4796 Insufficent
(11317) information
Colorado pikeminnow Green/Yampa River X X 1400 (Growl and Bouwes 5477 Stable Low
1998) (f966)
Desolation-Gray Canyons X U 1000 (Growl and Bouwes 5477 Stable Low
1998) (1966)
969 (1998 Annual Report)
Upper Colorado River X X 600 (Osmundson and 5477 Increasing Low
Burnham 1997) (1966)
735 (1998 Annual Report)
Definitions of Criteria:
Identified spawning stocks - Ripe fish collected on suspected spawning sites; larval fishes collected downstream of suspected spawning sites.
Recruitment -All life stages present at the site based on length frequency of the presumptive stock.
Population Status (Citation) -Documented estimates of population sizes with citation.
Interim Management Objectives -Identification of population sizes with confidence interval in Interim Management Objectives.
Status -Refers to the status of a presumptive stock from subjective judgment: stocks were considered to be increasing, stable, or declining.
Probability of extinction -Probability that a presumptive stock could be extirpated in the immediate future. High: Prevent immediate extinction due to limited or no
recruitment, augmentation may postpone or prevent immediate extinction; Medium Prevent further decline of population or range expand a population, some recruitment,
augment population while taking other management actions; Low: enhance a population, adequate recruitment, augmentation after other management actions (nonnative
fish control, habitat improvements) have been successful.
Two spawning sites have been identified one in the Yampa River and one in the Middle Green. Several razorback suckers have been observed moving between sites
among spawning years.
Bonytail are extremely rare in the upper basin; only occasional individuals are captured very infrequently; therefore, the probability of obtaining sufficient adult bonytails for
broodstock development is very remote. Hence, bonytails of Lake Mohave origin will be used to develop broodstoc~CS for recovery efforts in the upper basin.
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