9334 ‎(2)‎

• UCREFRP Catalog Number: 9334
• Author: Stickney, R. R.
• Title: Editor
• USFW Year: Series
• USFW - Doc Type: 1993
• Copyright Material: NO

Bonytail will be stocked into both the river and flooded bottomlands. Flooded bottomland
~ stocking will occur in Above Brennan (RM 2b$.5) and Johnson Bottom (RM 262.$) due to the
ability of these two site to overwinter fish. Stocking in the lower Green River will occur at Green
River State Park (RM 120). Stocking in the Colorado River will occur at Cisco (RM 110.5).
Monitoring efforts in the lower Green River and the Colorado River have indicated retention of
stocked bonytail below these stocking locations.
~ Implementation of this approach carries the following assumptions:
1) Numbers of bonytail to be stocked aze adequate to establish a minimum viable population
within each of these river reaches that will provide for adequate reproduction and
recruitment into the adult population to sustain itself. The current approach is not
~ designed to maintain the minimum viable population.
2) Other recovery efforts of the RIP (e.g., flow recommendations, flood plain reacquisition,
nonnative control) will provide for effective augmentationlreintroduction ofthe Green
River and Colorado River bonytail populations.
Impler~ntation of this approach carries the following inherent risks:
1) Genetic risks could include inbreeding depression and/or intrageneric hybridization
Inbreeding depression of bonytail may be a concern due to the extreme bottleneck the
~ species has experienced. Continuing to follow the guidance of the Genetics Management
Plan (Czapla 1999) should reduce the risk of this problem Stocking bonytail into the
Green and Colorado rivers may result in increased hybridization with humpback chub and
roundtail chub. However, McElroy and Douglas (1995) state that hybridization in Gila
may, in part, be a natural occurrence. Furthermore, there is evidence of hybridization in
~ the Gila complex prior to human impacts to the Colorado River basin (Dowling and
DeMarais 1993). Thus, interspecific hybridization within the Gila complex may not be
detrimental to the recovery of bonytail.
2) Ecological risks could include pathogen and/or pazasite transmission, and competition
~ and/or predation. Pathogens and parasites (i.e., Asian tapeworm) harbored by hatchery
reared fish could adversely impact wild fish populations. A resistant broodstock may
transmit pathogens into wild populations of bonytail or other sensitive or endangered
species, which may have little or no resistance. To reduce the risk of pathogen and
pazasite transmission, inspections are conducted by the Fisheries Experiment Station
~ (LTDWR) to ensure that culture facilities and stocked bonytail lots are specific pathogen
free and meet the requirements of the Fish Health Policy Board.
Hatchery-reared fish may compete for food and habitat with other native fish species.
Stocking large numbers of bonytail into the Green River may cause shifts in habitat use,
~ distnbution, and abundance of these species.
As with razorback sucker, predation on larval and small bonytail by nonnative species is a
concern. Stocking larger sized bonytail (average size of 200 mm TL) may decrease
mortality in the Green and Colorado rivers due to predation by nonnatives. Limited
~ ~