9498

• UCREFRP Catalog Number: 9498
• Author: Nesler, T. P.
• Title: Stocking Plan for Endangered Coloraod River Fish Species.
• USFW Year: 2001.
• USFW - Doc Type: Denver.
• Copyright Material: NO

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years to meet the objective of a multi-age group adult population at the designated
population abundance level.

2) Monitoring of stocked fish should be initiated after release, and conducted at a frequency
adequate to determine survival, distribution, density, and causes for mortality (e.g.
predation, starvation).

3) PIT tagging prior to stocking should be conducted for all stocked Colorado pikeminnow,
razorback sucker and bonytail.

4) Production of hatchery-raised fish and stocking numbers should be revised as necessary
to achieve best survival and post-stocking objectives based on monitoring results.

5) Stocking in a given reach should be discontinued if monitoring shows significant
abandonment of the target reach via downstream movement. Monitoring. of this displaced
cohort of stocked fish should be continued to document distribution and survival.

6) Translocation of late juvenile! early adult Colorado pikeminnow in the size range observed
for Colorado pikeminnow using the Redlands passage structure should be implemented as
a supplementary approach to stocking in both the Gunnison and Colorado rivers to
facilitate colonization and augmentation of populations in river reaches above existing
instream barriers.

7) Artificial passageways should be installed at Price-Stubb and Highline diversion dams to
facilitate movement of wild Colorado pikeminnow upstream in the Colorado River.

8) The scope of propagation facilities necessary to meet the stocking needs identified in this
plan should be estimated as quickly as possible, and consider priorities by species and river
reaches, to determine if shortfalls in production capacity exist.

Uncertainties

Implementation of this plan may be affected by the following biologicaI uncertainties that
were identified during its preparation. These include:
· All aspects of the life history and habitat needs of bonytail.
· SurvivaI rates of stocked fish in the wild.
· Variability in age of maturity for femaIe fish in the wild as a function of growth.
· Retention of stocked Colorado pikeminnow at Age 3 + in target reaches of upstream adult
habitat.
· Acquisition of natural migratory and spawning behaviors and effective production of
fertilized eggs in the wild by hatchery-raised fish, especially Colorado pikeminnow.

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