9666

• UCREFRP Catalog Number: 9666
• Author: VanHaverbeke, D. R. and Robert L. Simmonds Jr.
• Title: Final Report - The Feasibility of Developing a Program To Augment the Population of Humpback Chub ‎(Gila cypha)‎ In Grand Canyon.
• USFW Year: 2004.
• USFW - Doc Type: Flagstaff, AZ.
• Copyright Material: NO

a potential exists to effect density-dependant dynamics in the wild population. It is
recommended that if this action is performed, and is to succeed, a naturalistic rearing
facility and methodologies are used. Although the action, if properly performed,
appears to pose no serious biological risks to the wild population, the action would not
promote a self sustaining population, a feature required in the recovery criteria for the
species. In addition, this management action would likely require significant long term
effort and funding (years to decades) to achieve a sustained positive population
response.

Third, we address the feasibility of augmenting the Grand Canyon population of
humpback chub via translocation. Considered are 1) translocation of fish within the
LCR, and 2) translocation of fish into other tributaries (Bright Angel, Shinumo, and
Havasu creeks) in Grand Canyon.

Translocation of humpback chub within the LCR appears to offer potential for minor gain
in the wild census population, and may significantly expand the current spawning range
of the species, but may pose some potential for genetic risk to the main population in
Grand Canyon. These risks are related to inbreeding and depression of genetic
effective population size. Corrective measures to avoid these problems (should they
occur) appear to be available, provided monitoring and funding is emplaced to detect
them.

Translocation of humpback chub to other tributaries in Grand Canyon may offer
potential for augmenting mainstem aggregations, and some potential exists for creation
or significantexpansion of downstream aggregations. Translocation efforts to these
tributaries may need to be accompanied by sizeable predator removal efforts to effect a
change. Genetic risks to the main population of humpback chub in Grand Canyon
appear to be minor.

It is recommended that if any of these actions are pursued, they be carried out with the
priorities in mind of: 1) posing least potential for genetic harm to the wild population, and
2) having the best potential for promoting a self-sustaining wild population. This
suggests that translocations might be a first priority, followed by supplemental stocking
of wild caught age-O fish, and as a last resort the release of captive propagated fish.
Maintaining fish in captivity for refugium purposes poses no genetic risks to the wild
population, however, the release into the wild of captive reared individuals does pose
numerous genetic risks that need to be seriously evaluated.

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