8057

• UCREFRP Catalog Number: 8057
• Author: Bennett, J. R., D. A. Krieger, T. P. Nesler, L. E. Harris and R. B. Nehring.
• Title: An Assessment Of Fishery Management And Fish Production Alternatives To Reduce The Impact Of Whirling Disease In Colorado.
• USFW Year: 1996.
• USFW - Doc Type: Denver, Colorado.
• Copyright Material: NO

greatest possible variety of wildlife-related recreational opportunities (CRS, 33-1-101 [1]), we are
also expected to ensure the perpetuation of nongame/nonsport species as members of ecosystems
(CRS, 33-2-102).
This "dual mission" is underscored by the DOW's 1994 Long Range Plan (LRP), which
states, "The Division's foremost aim for the future will be to protect and enhance the viability of
all Colorado's wildlife species." In that same LRP, goal #12 calls for the DOW to diversify fishing
opportunities, and increase participation in fishing as the state's population grows, while
simultaneously increasing the level of angler satisfaction. Sub-goal 12.3 directs the DOW to
stock fish as appropriate to maintain angler satisfaction. Sub-goal 12.4 charges the agency to
protect and improve high-priority aquatic habitats. To accomplish these tasks, DOW
management programs must balance our recreation-based programs with protective components
for all of the state's wildlife species.
Along with the guidance from the LRP, DOW's direction for stocking fish comes from
CWC Policy and Administrative Directives, specifically:
>Commission Policy D-1 Management of Aquatic Wildlife (1975);
>Commission Policy D-2 Fish Stocking (1975);
>Commission Policy D-4 High Lake Management (1975);
>Commission Policy D-6 Wild Trout and Gold Medal Trout Mgt. (1992);
>Commission Policy D-9 The Stocking and Use of Fish Tested Positive for, or Exposed to,
the Whirling Disease Parasite, Myxobolus cerebralis (1996); and
>Administrative Directive F-1 Fish Management and Stocking (1976).
Colorado's surface acreage encompasses about 104,000 square miles, with some 54,000
linear miles of stream habitat, 24,000 miles of which are perennial; 15,000 surface acres of natural
lakes; and 250,000 acres of constructed ponds and reservoirs. These waters are inhabited by 112
species of fish--9 native sport species, 33 nonnative sport species, and 70 either native or
introduced nonsport species.
The state's aquatic habitats, categorized as coldwater streams (miles) or impoundments
(surface, acres), and warmwater streams (miles) or impoundments (surface acres) are listed in
Table 1, along with the WD status of each category. As shown, WD is not a concern in
warmwater habitats. However, in the coldwater habitat that the DOW manages, 670 coldwater
stream miles (1.3% of available habitat), and 10,400 coldwater surface acres (9.1% of available
habitat) now contain fish populations testing positive for Myxobolus cerebralis (MC), the
myxosporean parasite that can cause WD. A total of 2,550 stream miles has been exposed to the
WD parasite through stocking since 1988, but only 670 miles (26%) have tested positive. Some
exposed habitats have also been tested but have received negative test results, either because of
statistically invalid sample levels or because feral fish were not infected. More than 200 miles of
major trout streams, including the Colorado, Gunnison, Poudre, South Platte, and Rio Grande
rivers, are suffering significant rainbow trout population declines because of WD infection
(Nehring 1996). However, there are some stream segments (Elevenmile Canyon--S. Platte, Big
2