9595 ‎(2)‎

• UCREFRP Catalog Number: 9595
• Author: CRCT Task Force.
• Title: Conservation Agreement and Strategy for Colorado River Cutthroat Trout ‎(Oncorhynchus clarki pleuriticus)‎ in the States of Colorado, Utah, and Wyoming.
• USFW Year: 1999.
• USFW - Doc Type: Fort Collins, CO.
• Copyright Material: NO

DEFINITIONS AND ISSUES

A. Geographic Management Unit:

The range of the Colorado River cutthroat has been divided into 14 geographic management
units (GMUs) to bring a finer level of resolution to descriptions of population and habitat
distribution and related maintenance and restoration work. These GMUs reflect common sense
divisions of large areas based on river drainages. They do not necessarily reflect important
differences in genetic variability in the fish based in geography or other types of adaptation to
specific environments. As knowledge of the genetic variability of the fish increases, planning and
management should become increasingly based on conservation of the range of distinct population
segments that comprise the genome of the subspecies. This conceptual approach is assumed to be
analogous to evolutionarily significant units (ESUs) as surninarized by Monroe and Nielsen (1994).

B. Genetic Purity:

Colorado and Wyoming have adopted the following definitions of genetic purity in order to
provide consistency in interpretation of the various techniques which are available to assess genetic
purity:

A+: A pure population with unique phenotypic, genetic or historical qualities that suggest
special consideration and use for it in conservation planning.

A: A pure population with no evidence of hybridization with non-native salmonids.

A-: A population that is phenotypically representative but that has slight differences
from the norm due to natural variation or human-caused movement of CRCT from
other areas.

B+: A population where less than 5% of genetic markers or phenotypes indicate
hybridization with non-native salmonids.

B: A population where 5% or more but less than 10% of genetic markers or phenotypes
indicate hybridization with non-native salmonids.

B-: A population where 10% or more but less than 15% of genetic markers or
phenotypes indicate hybridization with non-native salmonids.

C: A population where 15% or more but less than 20% of genetic markers or
phenotypes indicate hybridization with non-native salmonids.

D: A population where 20% or more of genetic markers or phenotypes indicate
hybridization with non-native salmonids.

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