9528

• UCREFRP Catalog Number: 9528
• Author: Martinez, P. and N. P. Nibbelink.
• Title: Colorado Nonnative Fish Stocking Regulation Evaluation.
• USFW Year: 2004.
• USFW - Doc Type: Grand Junction, Laramie.
• Copyright Material: NO

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1. The Grand Canyon population is maintained as a core over a 5-
year period, starting with the first point estimate acceptable to the
Service, such that:
' a. The trend in adult (age 4+; >200 mm TL) point estimates
does not decline significantly, and
b. mean estimated recruitment age of age-3 (150-199 mm
' TL) naturally produced fish equals or exceeds adult
mortality, and
' c. each core population estimate exceeds 2,100 adults (MVP)
Delisting Criteria:
'
1. The Grand Canyon population is maintained as a core over a 3-
year period beyond downlisting, starting with the first point estimate
' acceptable to the Service, such that:
a. The trend in adult (age 4+; >200 mm TL) point estimates
does not decline significantly, and
' b. Mean estimated recruitment of age-3 (150-199 mm TL)
naturally produced fish equals or exceeds mean annual
adult mortality, and
' c. Each core population estimates exceeds 2,100 adults
(MVP)
' Management Strategies: The AMWG is currently developing a
Comprehensive Action and Management Plan for humpback chub
in Grand Canyon. Once completed, that plan will be reviewed in the
' context of the LCRMP to determine if additional actions are
necessary to meet the Recovery Goals.
' Razorback Sucker
' Current Status and Recovery Efforts: Based on collection records, the
razorback sucker is very rare in this reach with fewer than 20 individuals
reported since 1944 (Maddux et al. 1987, Minckley and Carothers 1978,
Valdez and Ryel 1995). Individuals that were collected were generally
' taken from side tributaries (Paris and Little Colorado rivers and Bright
Angel Creek. Hybrids (razorback sucker X flannelmouth sucker) have

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